tcsh(1) tcsh(1)

NAME

 tcsh - C shell with file name completion and command line editing

SYNOPSIS

 tcsh [-bcdefFimnqstvVxX] [-Dname[=value]] [arg ...]
 tcsh -l

DESCRIPTION

 tcsh is an enhanced but completely compatible version of the Berkeley
 UNIX C shell, csh(1) . It is a command language interpreter usable both
 as an interactive login shell and a shell script command processor. It
 includes a command-line editor (see The command-line editor), pro-
 grammable word completion (see Completion and listing), spelling cor-
 rection (see Spelling correction), a history mechanism (see History
 substitution), job control (see Jobs) and a C-like syntax. The NEW
 FEATURES section describes major enhancements of tcsh over csh(1) .
 Throughout this manual, features of tcsh not found in most csh(1) 
 implementations (specifically, the 4.4BSD csh) are labeled with `(+)',
 and features which are present in csh(1)  but not usually documented are
 labeled with `(u)'.
 Argument list processing
 If the first argument (argument 0) to the shell is `-' then it is a
 login shell. A login shell can be also specified by invoking the shell
 with the -l flag as the only argument.
 The rest of the flag arguments are interpreted as follows:
 -b Forces a ``break'' from option processing, causing any further
 shell arguments to be treated as non-option arguments. The remain-
 ing arguments will not be interpreted as shell options. This may
 be used to pass options to a shell script without confusion or pos-
 sible subterfuge. The shell will not run a set-user ID script
 without this option.
 -c Commands are read from the following argument (which must be
 present, and must be a single argument), stored in the command
 shell variable for reference, and executed. Any remaining argu-
 ments are placed in the argv shell variable.
 -d The shell loads the directory stack from ~/.cshdirs as described
 under Startup and shutdown, whether or not it is a login shell. (+)
 -Dname[=value]
 Sets the environment variable name to value. (Domain/OS only) (+)
 -e The shell exits if any invoked command terminates abnormally or
 yields a non-zero exit status.
 -f The shell does not load any resource or startup files, or perform
 any command hashing, and thus starts faster.
 -F The shell uses fork(2)  instead of vfork(2)  to spawn processes. (+)
 -i The shell is interactive and prompts for its top-level input, even
 if it appears to not be a terminal. Shells are interactive without
 this option if their inputs and outputs are terminals.
 -l The shell is a login shell. Applicable only if -l is the only flag
 specified.
 -m The shell loads ~/.tcshrc even if it does not belong to the effec-
 tive user. Newer versions of su(1)  can pass -m to the shell. (+)
 -n The shell parses commands but does not execute them. This aids in
 debugging shell scripts.
 -q The shell accepts SIGQUIT (see Signal handling) and behaves when it
 is used under a debugger. Job control is disabled. (u)
 -s Command input is taken from the standard input.
 -t The shell reads and executes a single line of input. A `\' may be
 used to escape the newline at the end of this line and continue
 onto another line.
 -v Sets the verbose shell variable, so that command input is echoed
 after history substitution.
 -x Sets the echo shell variable, so that commands are echoed immedi-
 ately before execution.
 -V Sets the verbose shell variable even before executing ~/.tcshrc.
 -X Is to -x as -V is to -v.
 --help
 Print a help message on the standard output and exit. (+)
 --version
 Print the version/platform/compilation options on the standard out-
 put and exit. This information is also contained in the version
 shell variable. (+)
 After processing of flag arguments, if arguments remain but none of the
 -c, -i, -s, or -t options were given, the first argument is taken as
 the name of a file of commands, or ``script'', to be executed. The
 shell opens this file and saves its name for possible resubstitution by
 `0ドル'. Because many systems use either the standard version 6 or ver-
 sion 7 shells whose shell scripts are not compatible with this shell,
 the shell uses such a `standard' shell to execute a script whose first
 character is not a `#', i.e., that does not start with a comment.
 Remaining arguments are placed in the argv shell variable.
 Startup and shutdown
 A login shell begins by executing commands from the system files
 /etc/csh.cshrc and /etc/csh.login. It then executes commands from
 files in the user's home directory: first ~/.tcshrc (+) or, if
 ~/.tcshrc is not found, ~/.cshrc, then ~/.history (or the value of the
 histfile shell variable), then ~/.login, and finally ~/.cshdirs (or the
 value of the dirsfile shell variable) (+). The shell may read
 /etc/csh.login before instead of after /etc/csh.cshrc, and ~/.login
 before instead of after ~/.tcshrc or ~/.cshrc and ~/.history, if so
 compiled; see the version shell variable. (+)
 Non-login shells read only /etc/csh.cshrc and ~/.tcshrc or ~/.cshrc on
 startup.
 For examples of startup files, please consult http://tcshrc.source-
 forge.net.
 Commands like stty(1)  and tset(1) , which need be run only once per
 login, usually go in one's ~/.login file. Users who need to use the
 same set of files with both csh(1)  and tcsh can have only a ~/.cshrc
 which checks for the existence of the tcsh shell variable (q.v.) before
 using tcsh-specific commands, or can have both a ~/.cshrc and a
 ~/.tcshrc which sources (see the builtin command) ~/.cshrc. The rest
 of this manual uses `~/.tcshrc' to mean `~/.tcshrc or, if ~/.tcshrc is
 not found, ~/.cshrc'.
 In the normal case, the shell begins reading commands from the termi-
 nal, prompting with `> '. (Processing of arguments and the use of the
 shell to process files containing command scripts are described later.)
 The shell repeatedly reads a line of command input, breaks it into
 words, places it on the command history list, parses it and executes
 each command in the line.
 One can log out by typing `^D' on an empty line, `logout' or `login' or
 via the shell's autologout mechanism (see the autologout shell vari-
 able). When a login shell terminates it sets the logout shell variable
 to `normal' or `automatic' as appropriate, then executes commands from
 the files /etc/csh.logout and ~/.logout. The shell may drop DTR on
 logout if so compiled; see the version shell variable.
 The names of the system login and logout files vary from system to sys-
 tem for compatibility with different csh(1)  variants; see FILES.
 Editing
 We first describe The command-line editor. The Completion and listing
 and Spelling correction sections describe two sets of functionality
 that are implemented as editor commands but which deserve their own
 treatment. Finally, Editor commands lists and describes the editor
 commands specific to the shell and their default bindings.
 The command-line editor (+)
 Command-line input can be edited using key sequences much like those
 used in GNU Emacs or vi(1) . The editor is active only when the edit
 shell variable is set, which it is by default in interactive shells.
 The bindkey builtin can display and change key bindings. Emacs-style
 key bindings are used by default (unless the shell was compiled other-
 wise; see the version shell variable), but bindkey can change the key
 bindings to vi-style bindings en masse.
 The shell always binds the arrow keys (as defined in the TERMCAP envi-
 ronment variable) to
 down down-history
 up up-history
 left backward-char
 right forward-char
 unless doing so would alter another single-character binding. One can
 set the arrow key escape sequences to the empty string with settc to
 prevent these bindings. The ANSI/VT100 sequences for arrow keys are
 always bound.
 Other key bindings are, for the most part, what Emacs and vi(1)  users
 would expect and can easily be displayed by bindkey, so there is no
 need to list them here. Likewise, bindkey can list the editor commands
 with a short description of each.
 Note that editor commands do not have the same notion of a ``word'' as
 does the shell. The editor delimits words with any non-alphanumeric
 characters not in the shell variable wordchars, while the shell recog-
 nizes only whitespace and some of the characters with special meanings
 to it, listed under Lexical structure.
 Completion and listing (+)
 The shell is often able to complete words when given a unique abbrevia-
 tion. Type part of a word (for example `ls /usr/lost') and hit the tab
 key to run the complete-word editor command. The shell completes the
 filename `/usr/lost' to `/usr/lost+found/', replacing the incomplete
 word with the complete word in the input buffer. (Note the terminal
 `/'; completion adds a `/' to the end of completed directories and a
 space to the end of other completed words, to speed typing and provide
 a visual indicator of successful completion. The addsuffix shell vari-
 able can be unset to prevent this.) If no match is found (perhaps
 `/usr/lost+found' doesn't exist), the terminal bell rings. If the word
 is already complete (perhaps there is a `/usr/lost' on your system, or
 perhaps you were thinking too far ahead and typed the whole thing) a
 `/' or space is added to the end if it isn't already there.
 Completion works anywhere in the line, not at just the end; completed
 text pushes the rest of the line to the right. Completion in the mid-
 dle of a word often results in leftover characters to the right of the
 cursor that need to be deleted.
 Commands and variables can be completed in much the same way. For
 example, typing `em[tab]' would complete `em' to `emacs' if emacs were
 the only command on your system beginning with `em'. Completion can
 find a command in any directory in path or if given a full pathname.
 Typing `echo $ar[tab]' would complete `$ar' to `$argv' if no other
 variable began with `ar'.
 The shell parses the input buffer to determine whether the word you
 want to complete should be completed as a filename, command or vari-
 able. The first word in the buffer and the first word following `;',
 `|', `|&', `&&' or `||' is considered to be a command. A word begin-
 ning with `$' is considered to be a variable. Anything else is a file-
 name. An empty line is `completed' as a filename.
 You can list the possible completions of a word at any time by typing
 `^D' to run the delete-char-or-list-or-eof editor command. The shell
 lists the possible completions using the ls-F builtin (q.v.) and re-
 prints the prompt and unfinished command line, for example:
 > ls /usr/l[^D]
 lbin/ lib/ local/ lost+found/
 > ls /usr/l
 If the autolist shell variable is set, the shell lists the remaining
 choices (if any) whenever completion fails:
 > set autolist
 > nm /usr/lib/libt[tab]
 libtermcap.a@ libtermlib.a@
 > nm /usr/lib/libterm
 If autolist is set to `ambiguous', choices are listed only when comple-
 tion fails and adds no new characters to the word being completed.
 A filename to be completed can contain variables, your own or others'
 home directories abbreviated with `~' (see Filename substitution) and
 directory stack entries abbreviated with `=' (see Directory stack sub-
 stitution). For example,
 > ls ~k[^D]
 kahn kas kellogg
 > ls ~ke[tab]
 > ls ~kellogg/
 or
 > set local = /usr/local
 > ls $lo[tab]
 > ls $local/[^D]
 bin/ etc/ lib/ man/ src/
 > ls $local/
 Note that variables can also be expanded explicitly with the expand-
 variables editor command.
 delete-char-or-list-or-eof lists at only the end of the line; in the
 middle of a line it deletes the character under the cursor and on an
 empty line it logs one out or, if ignoreeof is set, does nothing.
 `M-^D', bound to the editor command list-choices, lists completion pos-
 sibilities anywhere on a line, and list-choices (or any one of the
 related editor commands that do or don't delete, list and/or log out,
 listed under delete-char-or-list-or-eof) can be bound to `^D' with the
 bindkey builtin command if so desired.
 The complete-word-fwd and complete-word-back editor commands (not bound
 to any keys by default) can be used to cycle up and down through the
 list of possible completions, replacing the current word with the next
 or previous word in the list.
 The shell variable fignore can be set to a list of suffixes to be
 ignored by completion. Consider the following:
 > ls
 Makefile condiments.h~ main.o side.c
 README main.c meal side.o
 condiments.h main.c~
 > set fignore = (.o \~)
 > emacs ma[^D]
 main.c main.c~ main.o
 > emacs ma[tab]
 > emacs main.c
 `main.c~' and `main.o' are ignored by completion (but not listing),
 because they end in suffixes in fignore. Note that a `\' was needed in
 front of `~' to prevent it from being expanded to home as described
 under Filename substitution. fignore is ignored if only one completion
 is possible.
 If the complete shell variable is set to `enhance', completion 1)
 ignores case and 2) considers periods, hyphens and underscores (`.',
 `-' and `_') to be word separators and hyphens and underscores to be
 equivalent. If you had the following files
 comp.lang.c comp.lang.perl comp.std.c++
 comp.lang.c++ comp.std.c
 and typed `mail -f c.l.c[tab]', it would be completed to `mail -f
 comp.lang.c', and ^D would list `comp.lang.c' and `comp.lang.c++'.
 `mail -f c..c++[^D]' would list `comp.lang.c++' and `comp.std.c++'.
 Typing `rm a--file[^D]' in the following directory
 A_silly_file a-hyphenated-file another_silly_file
 would list all three files, because case is ignored and hyphens and
 underscores are equivalent. Periods, however, are not equivalent to
 hyphens or underscores.
 Completion and listing are affected by several other shell variables:
 recexact can be set to complete on the shortest possible unique match,
 even if more typing might result in a longer match:
 > ls
 fodder foo food foonly
 > set recexact
 > rm fo[tab]
 just beeps, because `fo' could expand to `fod' or `foo', but if we type
 another `o',
 > rm foo[tab]
 > rm foo
 the completion completes on `foo', even though `food' and `foonly' also
 match. autoexpand can be set to run the expand-history editor command
 before each completion attempt, autocorrect can be set to spelling-cor-
 rect the word to be completed (see Spelling correction) before each
 completion attempt and correct can be set to complete commands automat-
 ically after one hits `return'. matchbeep can be set to make comple-
 tion beep or not beep in a variety of situations, and nobeep can be set
 to never beep at all. nostat can be set to a list of directories
 and/or patterns that match directories to prevent the completion mecha-
 nism from stat(2) ing those directories. listmax and listmaxrows can be
 set to limit the number of items and rows (respectively) that are
 listed without asking first. recognize_only_executables can be set to
 make the shell list only executables when listing commands, but it is
 quite slow.
 Finally, the complete builtin command can be used to tell the shell how
 to complete words other than filenames, commands and variables. Com-
 pletion and listing do not work on glob-patterns (see Filename substi-
 tution), but the list-glob and expand-glob editor commands perform
 equivalent functions for glob-patterns.
 Spelling correction (+)
 The shell can sometimes correct the spelling of filenames, commands and
 variable names as well as completing and listing them.
 Individual words can be spelling-corrected with the spell-word editor
 command (usually bound to M-s and M-S) and the entire input buffer with
 spell-line (usually bound to M-$). The correct shell variable can be
 set to `cmd' to correct the command name or `all' to correct the entire
 line each time return is typed, and autocorrect can be set to correct
 the word to be completed before each completion attempt.
 When spelling correction is invoked in any of these ways and the shell
 thinks that any part of the command line is misspelled, it prompts with
 the corrected line:
 > set correct = cmd
 > lz /usr/bin
 CORRECT>ls /usr/bin (y|n|e|a)?
 One can answer `y' or space to execute the corrected line, `e' to leave
 the uncorrected command in the input buffer, `a' to abort the command
 as if `^C' had been hit, and anything else to execute the original line
 unchanged.
 Spelling correction recognizes user-defined completions (see the com-
 plete builtin command). If an input word in a position for which a
 completion is defined resembles a word in the completion list, spelling
 correction registers a misspelling and suggests the latter word as a
 correction. However, if the input word does not match any of the pos-
 sible completions for that position, spelling correction does not reg-
 ister a misspelling.
 Like completion, spelling correction works anywhere in the line, push-
 ing the rest of the line to the right and possibly leaving extra char-
 acters to the right of the cursor.
 Beware: spelling correction is not guaranteed to work the way one
 intends, and is provided mostly as an experimental feature. Sugges-
 tions and improvements are welcome.
 Editor commands (+)
 `bindkey' lists key bindings and `bindkey -l' lists and briefly
 describes editor commands. Only new or especially interesting editor
 commands are described here. See emacs(1)  and vi(1)  for descriptions
 of each editor's key bindings.
 The character or characters to which each command is bound by default
 is given in parentheses. `^character' means a control character and
 `M-character' a meta character, typed as escape-character on terminals
 without a meta key. Case counts, but commands that are bound to let-
 ters by default are bound to both lower- and uppercase letters for con-
 venience.
 complete-word (tab)
 Completes a word as described under Completion and listing.
 complete-word-back (not bound)
 Like complete-word-fwd, but steps up from the end of the list.
 complete-word-fwd (not bound)
 Replaces the current word with the first word in the list of
 possible completions. May be repeated to step down through the
 list. At the end of the list, beeps and reverts to the incom-
 plete word.
 complete-word-raw (^X-tab)
 Like complete-word, but ignores user-defined completions.
 copy-prev-word (M-^_)
 Copies the previous word in the current line into the input
 buffer. See also insert-last-word.
 dabbrev-expand (M-/)
 Expands the current word to the most recent preceding one for
 which the current is a leading substring, wrapping around the
 history list (once) if necessary. Repeating dabbrev-expand
 without any intervening typing changes to the next previous
 word etc., skipping identical matches much like history-search-
 backward does.
 delete-char (not bound)
 Deletes the character under the cursor. See also delete-char-
 or-list-or-eof.
 delete-char-or-eof (not bound)
 Does delete-char if there is a character under the cursor or
 end-of-file on an empty line. See also delete-char-or-list-or-
 eof.
 delete-char-or-list (not bound)
 Does delete-char if there is a character under the cursor or
 list-choices at the end of the line. See also delete-char-or-
 list-or-eof.
 delete-char-or-list-or-eof (^D)
 Does delete-char if there is a character under the cursor,
 list-choices at the end of the line or end-of-file on an empty
 line. See also those three commands, each of which does only a
 single action, and delete-char-or-eof, delete-char-or-list and
 list-or-eof, each of which does a different two out of the
 three.
 down-history (down-arrow, ^N)
 Like up-history, but steps down, stopping at the original input
 line.
 end-of-file (not bound)
 Signals an end of file, causing the shell to exit unless the
 ignoreeof shell variable (q.v.) is set to prevent this. See
 also delete-char-or-list-or-eof.
 expand-history (M-space)
 Expands history substitutions in the current word. See History
 substitution. See also magic-space, toggle-literal-history and
 the autoexpand shell variable.
 expand-glob (^X-*)
 Expands the glob-pattern to the left of the cursor. See File-
 name substitution.
 expand-line (not bound)
 Like expand-history, but expands history substitutions in each
 word in the input buffer,
 expand-variables (^X-$)
 Expands the variable to the left of the cursor. See Variable
 substitution.
 history-search-backward (M-p, M-P)
 Searches backwards through the history list for a command
 beginning with the current contents of the input buffer up to
 the cursor and copies it into the input buffer. The search
 string may be a glob-pattern (see Filename substitution) con-
 taining `*', `?', `[]' or `{}'. up-history and down-history
 will proceed from the appropriate point in the history list.
 Emacs mode only. See also history-search-forward and i-search-
 back.
 history-search-forward (M-n, M-N)
 Like history-search-backward, but searches forward.
 i-search-back (not bound)
 Searches backward like history-search-backward, copies the
 first match into the input buffer with the cursor positioned at
 the end of the pattern, and prompts with `bck: ' and the first
 match. Additional characters may be typed to extend the
 search, i-search-back may be typed to continue searching with
 the same pattern, wrapping around the history list if neces-
 sary, (i-search-back must be bound to a single character for
 this to work) or one of the following special characters may be
 typed:
 ^W Appends the rest of the word under the cursor to
 the search pattern.
 delete (or any character bound to backward-delete-char)
 Undoes the effect of the last character typed and
 deletes a character from the search pattern if
 appropriate.
 ^G If the previous search was successful, aborts the
 entire search. If not, goes back to the last suc-
 cessful search.
 escape Ends the search, leaving the current line in the
 input buffer.
 Any other character not bound to self-insert-command terminates
 the search, leaving the current line in the input buffer, and
 is then interpreted as normal input. In particular, a carriage
 return causes the current line to be executed. Emacs mode
 only. See also i-search-fwd and history-search-backward.
 i-search-fwd (not bound)
 Like i-search-back, but searches forward.
 insert-last-word (M-_)
 Inserts the last word of the previous input line (`!$') into
 the input buffer. See also copy-prev-word.
 list-choices (M-^D)
 Lists completion possibilities as described under Completion
 and listing. See also delete-char-or-list-or-eof and list-
 choices-raw.
 list-choices-raw (^X-^D)
 Like list-choices, but ignores user-defined completions.
 list-glob (^X-g, ^X-G)
 Lists (via the ls-F builtin) matches to the glob-pattern (see
 Filename substitution) to the left of the cursor.
 list-or-eof (not bound)
 Does list-choices or end-of-file on an empty line. See also
 delete-char-or-list-or-eof.
 magic-space (not bound)
 Expands history substitutions in the current line, like expand-
 history, and inserts a space. magic-space is designed to be
 bound to the space bar, but is not bound by default.
 normalize-command (^X-?)
 Searches for the current word in PATH and, if it is found,
 replaces it with the full path to the executable. Special
 characters are quoted. Aliases are expanded and quoted but
 commands within aliases are not. This command is useful with
 commands that take commands as arguments, e.g., `dbx' and `sh
 -x'.
 normalize-path (^X-n, ^X-N)
 Expands the current word as described under the `expand' set-
 ting of the symlinks shell variable.
 overwrite-mode (unbound)
 Toggles between input and overwrite modes.
 run-fg-editor (M-^Z)
 Saves the current input line and looks for a stopped job with a
 name equal to the last component of the file name part of the
 EDITOR or VISUAL environment variables, or, if neither is set,
 `ed' or `vi'. If such a job is found, it is restarted as if
 `fg %job' had been typed. This is used to toggle back and
 forth between an editor and the shell easily. Some people bind
 this command to `^Z' so they can do this even more easily.
 run-help (M-h, M-H)
 Searches for documentation on the current command, using the
 same notion of `current command' as the completion routines,
 and prints it. There is no way to use a pager; run-help is
 designed for short help files. If the special alias helpcom-
 mand is defined, it is run with the command name as a sole
 argument. Else, documentation should be in a file named com-
 mand.help, command.1, command.6, command.8 or command, which
 should be in one of the directories listed in the HPATH envi-
 ronment variable. If there is more than one help file only the
 first is printed.
 self-insert-command (text characters)
 In insert mode (the default), inserts the typed character into
 the input line after the character under the cursor. In over-
 write mode, replaces the character under the cursor with the
 typed character. The input mode is normally preserved between
 lines, but the inputmode shell variable can be set to `insert'
 or `overwrite' to put the editor in that mode at the beginning
 of each line. See also overwrite-mode.
 sequence-lead-in (arrow prefix, meta prefix, ^X)
 Indicates that the following characters are part of a multi-key
 sequence. Binding a command to a multi-key sequence really
 creates two bindings: the first character to sequence-lead-in
 and the whole sequence to the command. All sequences beginning
 with a character bound to sequence-lead-in are effectively
 bound to undefined-key unless bound to another command.
 spell-line (M-$)
 Attempts to correct the spelling of each word in the input
 buffer, like spell-word, but ignores words whose first charac-
 ter is one of `-', `!', `^' or `%', or which contain `\', `*'
 or `?', to avoid problems with switches, substitutions and the
 like. See Spelling correction.
 spell-word (M-s, M-S)
 Attempts to correct the spelling of the current word as
 described under Spelling correction. Checks each component of
 a word which appears to be a pathname.
 toggle-literal-history (M-r, M-R)
 Expands or `unexpands' history substitutions in the input
 buffer. See also expand-history and the autoexpand shell vari-
 able.
 undefined-key (any unbound key)
 Beeps.
 up-history (up-arrow, ^P)
 Copies the previous entry in the history list into the input
 buffer. If histlit is set, uses the literal form of the entry.
 May be repeated to step up through the history list, stopping
 at the top.
 vi-search-back (?)
 Prompts with `?' for a search string (which may be a glob-pat-
 tern, as with history-search-backward), searches for it and
 copies it into the input buffer. The bell rings if no match is
 found. Hitting return ends the search and leaves the last
 match in the input buffer. Hitting escape ends the search and
 executes the match. vi mode only.
 vi-search-fwd (/)
 Like vi-search-back, but searches forward.
 which-command (M-?)
 Does a which (see the description of the builtin command) on
 the first word of the input buffer.
 yank-pop (M-y)
 When executed immediately after a yank or another yank-pop,
 replaces the yanked string with the next previous string from
 the killring. This also has the effect of rotating the kill-
 ring, such that this string will be considered the most
 recently killed by a later yank command. Repeating yank-pop
 will cycle through the killring any number of times.
 Lexical structure
 The shell splits input lines into words at blanks and tabs. The spe-
 cial characters `&', `|', `;', `<', `>', `(', and `)' and the doubled
 characters `&&', `||', `<<' and `>>' are always separate words, whether
 or not they are surrounded by whitespace.
 When the shell's input is not a terminal, the character `#' is taken to
 begin a comment. Each `#' and the rest of the input line on which it
 appears is discarded before further parsing.
 A special character (including a blank or tab) may be prevented from
 having its special meaning, and possibly made part of another word, by
 preceding it with a backslash (`\') or enclosing it in single (`''),
 double (`"') or backward (``') quotes. When not otherwise quoted a
 newline preceded by a `\' is equivalent to a blank, but inside quotes
 this sequence results in a newline.
 Furthermore, all Substitutions (see below) except History substitution
 can be prevented by enclosing the strings (or parts of strings) in
 which they appear with single quotes or by quoting the crucial charac-
 ter(s) (e.g., `$' or ``' for Variable substitution or Command substitu-
 tion respectively) with `\'. (Alias substitution is no exception:
 quoting in any way any character of a word for which an alias has been
 defined prevents substitution of the alias. The usual way of quoting
 an alias is to precede it with a backslash.) History substitution is
 prevented by backslashes but not by single quotes. Strings quoted with
 double or backward quotes undergo Variable substitution and Command
 substitution, but other substitutions are prevented.
 Text inside single or double quotes becomes a single word (or part of
 one). Metacharacters in these strings, including blanks and tabs, do
 not form separate words. Only in one special case (see Command substi-
 tution below) can a double-quoted string yield parts of more than one
 word; single-quoted strings never do. Backward quotes are special:
 they signal Command substitution (q.v.), which may result in more than
 one word.
 Quoting complex strings, particularly strings which themselves contain
 quoting characters, can be confusing. Remember that quotes need not be
 used as they are in human writing! It may be easier to quote not an
 entire string, but only those parts of the string which need quoting,
 using different types of quoting to do so if appropriate.
 The backslash_quote shell variable (q.v.) can be set to make back-
 slashes always quote `\', `'', and `"'. (+) This may make complex
 quoting tasks easier, but it can cause syntax errors in csh(1)  scripts.
 Substitutions
 We now describe the various transformations the shell performs on the
 input in the order in which they occur. We note in passing the data
 structures involved and the commands and variables which affect them.
 Remember that substitutions can be prevented by quoting as described
 under Lexical structure.
 History substitution
 Each command, or ``event'', input from the terminal is saved in the
 history list. The previous command is always saved, and the history
 shell variable can be set to a number to save that many commands. The
 histdup shell variable can be set to not save duplicate events or con-
 secutive duplicate events.
 Saved commands are numbered sequentially from 1 and stamped with the
 time. It is not usually necessary to use event numbers, but the cur-
 rent event number can be made part of the prompt by placing an `!' in
 the prompt shell variable.
 The shell actually saves history in expanded and literal (unexpanded)
 forms. If the histlit shell variable is set, commands that display and
 store history use the literal form.
 The history builtin command can print, store in a file, restore and
 clear the history list at any time, and the savehist and histfile shell
 variables can be can be set to store the history list automatically on
 logout and restore it on login.
 History substitutions introduce words from the history list into the
 input stream, making it easy to repeat commands, repeat arguments of a
 previous command in the current command, or fix spelling mistakes in
 the previous command with little typing and a high degree of confi-
 dence.
 History substitutions begin with the character `!'. They may begin
 anywhere in the input stream, but they do not nest. The `!' may be
 preceded by a `\' to prevent its special meaning; for convenience, a
 `!' is passed unchanged when it is followed by a blank, tab, newline,
 `=' or `('. History substitutions also occur when an input line begins
 with `^'. This special abbreviation will be described later. The
 characters used to signal history substitution (`!' and `^') can be
 changed by setting the histchars shell variable. Any input line which
 contains a history substitution is printed before it is executed.
 A history substitution may have an ``event specification'', which indi-
 cates the event from which words are to be taken, a ``word designa-
 tor'', which selects particular words from the chosen event, and/or a
 ``modifier'', which manipulates the selected words.
 An event specification can be
 n A number, referring to a particular event
 -n An offset, referring to the event n before the current
 event
 # The current event. This should be used carefully in
 csh(1) , where there is no check for recursion. tcsh allows
 10 levels of recursion. (+)
 ! The previous event (equivalent to `-1')
 s The most recent event whose first word begins with the
 string s
 ?s? The most recent event which contains the string s. The
 second `?' can be omitted if it is immediately followed by
 a newline.
 For example, consider this bit of someone's history list:
 9 8:30 nroff -man wumpus.man
 10 8:31 cp wumpus.man wumpus.man.old
 11 8:36 vi wumpus.man
 12 8:37 diff wumpus.man.old wumpus.man
 The commands are shown with their event numbers and time stamps. The
 current event, which we haven't typed in yet, is event 13. `!11' and
 `!-2' refer to event 11. `!!' refers to the previous event, 12. `!!'
 can be abbreviated `!' if it is followed by `:' (`:' is described
 below). `!n' refers to event 9, which begins with `n'. `!?old?' also
 refers to event 12, which contains `old'. Without word designators or
 modifiers history references simply expand to the entire event, so we
 might type `!cp' to redo the copy command or `!!|more' if the `diff'
 output scrolled off the top of the screen.
 History references may be insulated from the surrounding text with
 braces if necessary. For example, `!vdoc' would look for a command
 beginning with `vdoc', and, in this example, not find one, but
 `!{v}doc' would expand unambiguously to `vi wumpus.mandoc'. Even in
 braces, history substitutions do not nest.
 (+) While csh(1)  expands, for example, `!3d' to event 3 with the letter
 `d' appended to it, tcsh expands it to the last event beginning with
 `3d'; only completely numeric arguments are treated as event numbers.
 This makes it possible to recall events beginning with numbers. To
 expand `!3d' as in csh(1)  say `!{3}d'.
 To select words from an event we can follow the event specification by
 a `:' and a designator for the desired words. The words of an input
 line are numbered from 0, the first (usually command) word being 0, the
 second word (first argument) being 1, etc. The basic word designators
 are:
 0 The first (command) word
 n The nth argument
 ^ The first argument, equivalent to `1'
 $ The last argument
 % The word matched by an ?s? search
 x-y A range of words
 -y Equivalent to `0-y'
 * Equivalent to `^-$', but returns nothing if the event con-
 tains only 1 word
 x* Equivalent to `x-$'
 x- Equivalent to `x*', but omitting the last word (`$')
 Selected words are inserted into the command line separated by single
 blanks. For example, the `diff' command in the previous example might
 have been typed as `diff !!:1.old !!:1' (using `:1' to select the first
 argument from the previous event) or `diff !-2:2 !-2:1' to select and
 swap the arguments from the `cp' command. If we didn't care about the
 order of the `diff' we might have said `diff !-2:1-2' or simply `diff
 !-2:*'. The `cp' command might have been written `cp wumpus.man
 !#:1.old', using `#' to refer to the current event. `!n:- hurkle.man'
 would reuse the first two words from the `nroff' command to say `nroff
 -man hurkle.man'.
 The `:' separating the event specification from the word designator can
 be omitted if the argument selector begins with a `^', `$', `*', `%' or
 `-'. For example, our `diff' command might have been `diff !!^.old
 !!^' or, equivalently, `diff !!$.old !!$'. However, if `!!' is abbre-
 viated `!', an argument selector beginning with `-' will be interpreted
 as an event specification.
 A history reference may have a word designator but no event specifica-
 tion. It then references the previous command. Continuing our `diff'
 example, we could have said simply `diff !^.old !^' or, to get the
 arguments in the opposite order, just `diff !*'.
 The word or words in a history reference can be edited, or ``modi-
 fied'', by following it with one or more modifiers, each preceded by a
 `:':
 h Remove a trailing pathname component, leaving the head.
 t Remove all leading pathname components, leaving the tail.
 r Remove a filename extension `.xxx', leaving the root name.
 e Remove all but the extension.
 u Uppercase the first lowercase letter.
 l Lowercase the first uppercase letter.
 s/l/r/ Substitute l for r. l is simply a string like r, not a
 regular expression as in the eponymous ed(1)  command. Any
 character may be used as the delimiter in place of `/'; a
 `\' can be used to quote the delimiter inside l and r. The
 character `&' in the r is replaced by l; `\' also quotes
 `&'. If l is empty (``''), the l from a previous substitu-
 tion or the s from a previous search or event number in
 event specification is used. The trailing delimiter may be
 omitted if it is immediately followed by a newline.
 & Repeat the previous substitution.
 g Apply the following modifier once to each word.
 a (+) Apply the following modifier as many times as possible to a
 single word. `a' and `g' can be used together to apply a
 modifier globally. With the `s' modifier, only the pat-
 terns contained in the original word are substituted, not
 patterns that contain any substitution result.
 p Print the new command line but do not execute it.
 q Quote the substituted words, preventing further substitu-
 tions.
 x Like q, but break into words at blanks, tabs and newlines.
 Modifiers are applied to only the first modifiable word (unless `g' is
 used). It is an error for no word to be modifiable.
 For example, the `diff' command might have been written as `diff wum-
 pus.man.old !#^:r', using `:r' to remove `.old' from the first argument
 on the same line (`!#^'). We could say `echo hello out there', then
 `echo !*:u' to capitalize `hello', `echo !*:au' to say it out loud, or
 `echo !*:agu' to really shout. We might follow `mail -s "I forgot my
 password" rot' with `!:s/rot/root' to correct the spelling of `root'
 (but see Spelling correction for a different approach).
 There is a special abbreviation for substitutions. `^', when it is the
 first character on an input line, is equivalent to `!:s^'. Thus we
 might have said `^rot^root' to make the spelling correction in the pre-
 vious example. This is the only history substitution which does not
 explicitly begin with `!'.
 (+) In csh as such, only one modifier may be applied to each history or
 variable expansion. In tcsh, more than one may be used, for example
 % mv wumpus.man /usr/man/man1/wumpus.1
 % man !$:t:r
 man wumpus
 In csh, the result would be `wumpus.1:r'. A substitution followed by a
 colon may need to be insulated from it with braces:
 > mv a.out /usr/games/wumpus
 > setenv PATH !$:h:$PATH
 Bad ! modifier: $.
 > setenv PATH !{-2$:h}:$PATH
 setenv PATH /usr/games:/bin:/usr/bin:.
 The first attempt would succeed in csh but fails in tcsh, because tcsh
 expects another modifier after the second colon rather than `$'.
 Finally, history can be accessed through the editor as well as through
 the substitutions just described. The up- and down-history, history-
 search-backward and -forward, i-search-back and -fwd, vi-search-back
 and -fwd, copy-prev-word and insert-last-word editor commands search
 for events in the history list and copy them into the input buffer.
 The toggle-literal-history editor command switches between the expanded
 and literal forms of history lines in the input buffer. expand-history
 and expand-line expand history substitutions in the current word and in
 the entire input buffer respectively.
 Alias substitution
 The shell maintains a list of aliases which can be set, unset and
 printed by the alias and unalias commands. After a command line is
 parsed into simple commands (see Commands) the first word of each com-
 mand, left-to-right, is checked to see if it has an alias. If so, the
 first word is replaced by the alias. If the alias contains a history
 reference, it undergoes History substitution (q.v.) as though the orig-
 inal command were the previous input line. If the alias does not con-
 tain a history reference, the argument list is left untouched.
 Thus if the alias for `ls' were `ls -l' the command `ls /usr' would
 become `ls -l /usr', the argument list here being undisturbed. If the
 alias for `lookup' were `grep !^ /etc/passwd' then `lookup bill' would
 become `grep bill /etc/passwd'. Aliases can be used to introduce
 parser metasyntax. For example, `alias print 'pr \!* | lpr'' defines a
 ``command'' (`print') which pr(1) s its arguments to the line printer.
 Alias substitution is repeated until the first word of the command has
 no alias. If an alias substitution does not change the first word (as
 in the previous example) it is flagged to prevent a loop. Other loops
 are detected and cause an error.
 Some aliases are referred to by the shell; see Special aliases.
 Variable substitution
 The shell maintains a list of variables, each of which has as value a
 list of zero or more words. The values of shell variables can be dis-
 played and changed with the set and unset commands. The system main-
 tains its own list of ``environment'' variables. These can be dis-
 played and changed with printenv, setenv and unsetenv.
 (+) Variables may be made read-only with `set -r' (q.v.) Read-only
 variables may not be modified or unset; attempting to do so will cause
 an error. Once made read-only, a variable cannot be made writable, so
 `set -r' should be used with caution. Environment variables cannot be
 made read-only.
 Some variables are set by the shell or referred to by it. For
 instance, the argv variable is an image of the shell's argument list,
 and words of this variable's value are referred to in special ways.
 Some of the variables referred to by the shell are toggles; the shell
 does not care what their value is, only whether they are set or not.
 For instance, the verbose variable is a toggle which causes command
 input to be echoed. The -v command line option sets this variable.
 Special shell variables lists all variables which are referred to by
 the shell.
 Other operations treat variables numerically. The `@' command permits
 numeric calculations to be performed and the result assigned to a vari-
 able. Variable values are, however, always represented as (zero or
 more) strings. For the purposes of numeric operations, the null string
 is considered to be zero, and the second and subsequent words of multi-
 word values are ignored.
 After the input line is aliased and parsed, and before each command is
 executed, variable substitution is performed keyed by `$' characters.
 This expansion can be prevented by preceding the `$' with a `\' except
 within `"'s where it always occurs, and within `''s where it never
 occurs. Strings quoted by ``' are interpreted later (see Command sub-
 stitution below) so `$' substitution does not occur there until later,
 if at all. A `$' is passed unchanged if followed by a blank, tab, or
 end-of-line.
 Input/output redirections are recognized before variable expansion, and
 are variable expanded separately. Otherwise, the command name and
 entire argument list are expanded together. It is thus possible for
 the first (command) word (to this point) to generate more than one
 word, the first of which becomes the command name, and the rest of
 which become arguments.
 Unless enclosed in `"' or given the `:q' modifier the results of vari-
 able substitution may eventually be command and filename substituted.
 Within `"', a variable whose value consists of multiple words expands
 to a (portion of a) single word, with the words of the variable's value
 separated by blanks. When the `:q' modifier is applied to a substitu-
 tion the variable will expand to multiple words with each word sepa-
 rated by a blank and quoted to prevent later command or filename sub-
 stitution.
 The following metasequences are provided for introducing variable val-
 ues into the shell input. Except as noted, it is an error to reference
 a variable which is not set.
 $name
 ${name} Substitutes the words of the value of variable name, each sepa-
 rated by a blank. Braces insulate name from following charac-
 ters which would otherwise be part of it. Shell variables have
 names consisting of letters and digits starting with a letter.
 The underscore character is considered a letter. If name is
 not a shell variable, but is set in the environment, then that
 value is returned (but some of the other forms given below are
 not available in this case).
 $name[selector]
 ${name[selector]}
 Substitutes only the selected words from the value of name.
 The selector is subjected to `$' substitution and may consist
 of a single number or two numbers separated by a `-'. The
 first word of a variable's value is numbered `1'. If the first
 number of a range is omitted it defaults to `1'. If the last
 member of a range is omitted it defaults to `$#name'. The
 selector `*' selects all words. It is not an error for a range
 to be empty if the second argument is omitted or in range.
 0ドル Substitutes the name of the file from which command input is
 being read. An error occurs if the name is not known.
 $number
 ${number}
 Equivalent to `$argv[number]'.
 $* Equivalent to `$argv', which is equivalent to `$argv[*]'.
 The `:' modifiers described under History substitution, except for
 `:p', can be applied to the substitutions above. More than one may be
 used. (+) Braces may be needed to insulate a variable substitution
 from a literal colon just as with History substitution (q.v.); any mod-
 ifiers must appear within the braces.
 The following substitutions can not be modified with `:' modifiers.
 $?name
 ${?name}
 Substitutes the string `1' if name is set, `0' if it is not.
 $?0 Substitutes `1' if the current input filename is known, `0' if
 it is not. Always `0' in interactive shells.
 $#name
 ${#name}
 Substitutes the number of words in name.
 $# Equivalent to `$#argv'. (+)
 $%name
 ${%name}
 Substitutes the number of characters in name. (+)
 $%number
 ${%number}
 Substitutes the number of characters in $argv[number]. (+)
 $? Equivalent to `$status'. (+)
 $$ Substitutes the (decimal) process number of the (parent) shell.
 $! Substitutes the (decimal) process number of the last background
 process started by this shell. (+)
 $_ Substitutes the command line of the last command executed. (+)
 $< Substitutes a line from the standard input, with no further
 interpretation thereafter. It can be used to read from the
 keyboard in a shell script. (+) While csh always quotes $<, as
 if it were equivalent to `$<:q', tcsh does not. Furthermore,
 when tcsh is waiting for a line to be typed the user may type
 an interrupt to interrupt the sequence into which the line is
 to be substituted, but csh does not allow this.
 The editor command expand-variables, normally bound to `^X-$', can be
 used to interactively expand individual variables.
 Command, filename and directory stack substitution
 The remaining substitutions are applied selectively to the arguments of
 builtin commands. This means that portions of expressions which are
 not evaluated are not subjected to these expansions. For commands
 which are not internal to the shell, the command name is substituted
 separately from the argument list. This occurs very late, after input-
 output redirection is performed, and in a child of the main shell.
 Command substitution
 Command substitution is indicated by a command enclosed in ``'. The
 output from such a command is broken into separate words at blanks,
 tabs and newlines, and null words are discarded. The output is vari-
 able and command substituted and put in place of the original string.
 Command substitutions inside double quotes (`"') retain blanks and
 tabs; only newlines force new words. The single final newline does not
 force a new word in any case. It is thus possible for a command sub-
 stitution to yield only part of a word, even if the command outputs a
 complete line.
 By default, the shell since version 6.12 replaces all newline and car-
 riage return characters in the command by spaces. If this is switched
 off by unsetting csubstnonl, newlines separate commands as usual.
 Filename substitution
 If a word contains any of the characters `*', `?', `[' or `{' or begins
 with the character `~' it is a candidate for filename substitution,
 also known as ``globbing''. This word is then regarded as a pattern
 (``glob-pattern''), and replaced with an alphabetically sorted list of
 file names which match the pattern.
 In matching filenames, the character `.' at the beginning of a filename
 or immediately following a `/', as well as the character `/' must be
 matched explicitly. The character `*' matches any string of charac-
 ters, including the null string. The character `?' matches any single
 character. The sequence `[...]' matches any one of the characters
 enclosed. Within `[...]', a pair of characters separated by `-'
 matches any character lexically between the two.
 (+) Some glob-patterns can be negated: The sequence `[^...]' matches
 any single character not specified by the characters and/or ranges of
 characters in the braces.
 An entire glob-pattern can also be negated with `^':
 > echo *
 bang crash crunch ouch
 > echo ^cr*
 bang ouch
 Glob-patterns which do not use `?', `*', or `[]' or which use `{}' or
 `~' (below) are not negated correctly.
 The metanotation `a{b,c,d}e' is a shorthand for `abe ace ade'. Left-
 to-right order is preserved: `/usr/source/s1/{oldls,ls}.c' expands to
 `/usr/source/s1/oldls.c /usr/source/s1/ls.c'. The results of matches
 are sorted separately at a low level to preserve this order:
 `../{memo,*box}' might expand to `../memo ../box ../mbox'. (Note that
 `memo' was not sorted with the results of matching `*box'.) It is not
 an error when this construct expands to files which do not exist, but
 it is possible to get an error from a command to which the expanded
 list is passed. This construct may be nested. As a special case the
 words `{', `}' and `{}' are passed undisturbed.
 The character `~' at the beginning of a filename refers to home direc-
 tories. Standing alone, i.e., `~', it expands to the invoker's home
 directory as reflected in the value of the home shell variable. When
 followed by a name consisting of letters, digits and `-' characters the
 shell searches for a user with that name and substitutes their home
 directory; thus `~ken' might expand to `/usr/ken' and `~ken/chmach' to
 `/usr/ken/chmach'. If the character `~' is followed by a character
 other than a letter or `/' or appears elsewhere than at the beginning
 of a word, it is left undisturbed. A command like `setenv MANPATH
 /usr/man:/usr/local/man:~/lib/man' does not, therefore, do home direc-
 tory substitution as one might hope.
 It is an error for a glob-pattern containing `*', `?', `[' or `~', with
 or without `^', not to match any files. However, only one pattern in a
 list of glob-patterns must match a file (so that, e.g., `rm *.a *.c
 *.o' would fail only if there were no files in the current directory
 ending in `.a', `.c', or `.o'), and if the nonomatch shell variable is
 set a pattern (or list of patterns) which matches nothing is left
 unchanged rather than causing an error.
 The noglob shell variable can be set to prevent filename substitution,
 and the expand-glob editor command, normally bound to `^X-*', can be
 used to interactively expand individual filename substitutions.
 Directory stack substitution (+)
 The directory stack is a list of directories, numbered from zero, used
 by the pushd, popd and dirs builtin commands (q.v.). dirs can print,
 store in a file, restore and clear the directory stack at any time, and
 the savedirs and dirsfile shell variables can be set to store the
 directory stack automatically on logout and restore it on login. The
 dirstack shell variable can be examined to see the directory stack and
 set to put arbitrary directories into the directory stack.
 The character `=' followed by one or more digits expands to an entry in
 the directory stack. The special case `=-' expands to the last direc-
 tory in the stack. For example,
 > dirs -v
 0 /usr/bin
 1 /usr/spool/uucp
 2 /usr/accts/sys
 > echo =1
 /usr/spool/uucp
 > echo =0/calendar
 /usr/bin/calendar
 > echo =-
 /usr/accts/sys
 The noglob and nonomatch shell variables and the expand-glob editor
 command apply to directory stack as well as filename substitutions.
 Other substitutions (+)
 There are several more transformations involving filenames, not
 strictly related to the above but mentioned here for completeness. Any
 filename may be expanded to a full path when the symlinks variable
 (q.v.) is set to `expand'. Quoting prevents this expansion, and the
 normalize-path editor command does it on demand. The normalize-command
 editor command expands commands in PATH into full paths on demand.
 Finally, cd and pushd interpret `-' as the old working directory
 (equivalent to the shell variable owd). This is not a substitution at
 all, but an abbreviation recognized by only those commands. Nonethe-
 less, it too can be prevented by quoting.
 Commands
 The next three sections describe how the shell executes commands and
 deals with their input and output.
 Simple commands, pipelines and sequences
 A simple command is a sequence of words, the first of which specifies
 the command to be executed. A series of simple commands joined by `|'
 characters forms a pipeline. The output of each command in a pipeline
 is connected to the input of the next.
 Simple commands and pipelines may be joined into sequences with `;',
 and will be executed sequentially. Commands and pipelines can also be
 joined into sequences with `||' or `&&', indicating, as in the C lan-
 guage, that the second is to be executed only if the first fails or
 succeeds respectively.
 A simple command, pipeline or sequence may be placed in parentheses,
 `()', to form a simple command, which may in turn be a component of a
 pipeline or sequence. A command, pipeline or sequence can be executed
 without waiting for it to terminate by following it with an `&'.
 Builtin and non-builtin command execution
 Builtin commands are executed within the shell. If any component of a
 pipeline except the last is a builtin command, the pipeline is executed
 in a subshell.
 Parenthesized commands are always executed in a subshell.
 (cd; pwd); pwd
 thus prints the home directory, leaving you where you were (printing
 this after the home directory), while
 cd; pwd
 leaves you in the home directory. Parenthesized commands are most
 often used to prevent cd from affecting the current shell.
 When a command to be executed is found not to be a builtin command the
 shell attempts to execute the command via execve(2) . Each word in the
 variable path names a directory in which the shell will look for the
 command. If the shell is not given a -f option, the shell hashes the
 names in these directories into an internal table so that it will try
 an execve(2)  in only a directory where there is a possibility that the
 command resides there. This greatly speeds command location when a
 large number of directories are present in the search path. This hash-
 ing mechanism is not used:
 1. If hashing is turned explicitly off via unhash.
 2. If the shell was given a -f argument.
 3. For each directory component of path which does not begin with a
 `/'.
 4. If the command contains a `/'.
 In the above four cases the shell concatenates each component of the
 path vector with the given command name to form a path name of a file
 which it then attempts to execute it. If execution is successful, the
 search stops.
 If the file has execute permissions but is not an executable to the
 system (i.e., it is neither an executable binary nor a script that
 specifies its interpreter), then it is assumed to be a file containing
 shell commands and a new shell is spawned to read it. The shell spe-
 cial alias may be set to specify an interpreter other than the shell
 itself.
 On systems which do not understand the `#!' script interpreter conven-
 tion the shell may be compiled to emulate it; see the version shell
 variable. If so, the shell checks the first line of the file to see if
 it is of the form `#!interpreter arg ...'. If it is, the shell starts
 interpreter with the given args and feeds the file to it on standard
 input.
 Input/output
 The standard input and standard output of a command may be redirected
 with the following syntax:
 < name Open file name (which is first variable, command and filename
 expanded) as the standard input.
 << word Read the shell input up to a line which is identical to word.
 word is not subjected to variable, filename or command substi-
 tution, and each input line is compared to word before any sub-
 stitutions are done on this input line. Unless a quoting `\',
 `"', `' or ``' appears in word variable and command substitu-
 tion is performed on the intervening lines, allowing `\' to
 quote `$', `\' and ``'. Commands which are substituted have
 all blanks, tabs, and newlines preserved, except for the final
 newline which is dropped. The resultant text is placed in an
 anonymous temporary file which is given to the command as stan-
 dard input.
 > name
 >! name
 >& name
 >&! name
 The file name is used as standard output. If the file does not
 exist then it is created; if the file exists, it is truncated,
 its previous contents being lost.
 If the shell variable noclobber is set, then the file must not
 exist or be a character special file (e.g., a terminal or
 `/dev/null') or an error results. This helps prevent acciden-
 tal destruction of files. In this case the `!' forms can be
 used to suppress this check.
 The forms involving `&' route the diagnostic output into the
 specified file as well as the standard output. name is
 expanded in the same way as `<' input filenames are.
 >> name
 >>& name
 >>! name
 >>&! name
 Like `>', but appends output to the end of name. If the shell
 variable noclobber is set, then it is an error for the file not
 to exist, unless one of the `!' forms is given.
 A command receives the environment in which the shell was invoked as
 modified by the input-output parameters and the presence of the command
 in a pipeline. Thus, unlike some previous shells, commands run from a
 file of shell commands have no access to the text of the commands by
 default; rather they receive the original standard input of the shell.
 The `<<' mechanism should be used to present inline data. This permits
 shell command scripts to function as components of pipelines and allows
 the shell to block read its input. Note that the default standard
 input for a command run detached is not the empty file /dev/null, but
 the original standard input of the shell. If this is a terminal and if
 the process attempts to read from the terminal, then the process will
 block and the user will be notified (see Jobs).
 Diagnostic output may be directed through a pipe with the standard out-
 put. Simply use the form `|&' rather than just `|'.
 The shell cannot presently redirect diagnostic output without also
 redirecting standard output, but `(command > output-file) >& error-
 file' is often an acceptable workaround. Either output-file or error-
 file may be `/dev/tty' to send output to the terminal.
 Features
 Having described how the shell accepts, parses and executes command
 lines, we now turn to a variety of its useful features.
 Control flow
 The shell contains a number of commands which can be used to regulate
 the flow of control in command files (shell scripts) and (in limited
 but useful ways) from terminal input. These commands all operate by
 forcing the shell to reread or skip in its input and, due to the imple-
 mentation, restrict the placement of some of the commands.
 The foreach, switch, and while statements, as well as the if-then-else
 form of the if statement, require that the major keywords appear in a
 single simple command on an input line as shown below.
 If the shell's input is not seekable, the shell buffers up input when-
 ever a loop is being read and performs seeks in this internal buffer to
 accomplish the rereading implied by the loop. (To the extent that this
 allows, backward gotos will succeed on non-seekable inputs.)
 Expressions
 The if, while and exit builtin commands use expressions with a common
 syntax. The expressions can include any of the operators described in
 the next three sections. Note that the @ builtin command (q.v.) has
 its own separate syntax.
 Logical, arithmetical and comparison operators
 These operators are similar to those of C and have the same precedence.
 They include
 || && | ^ & == != =~ !~ <= >=
 < > << >> + - * / % ! ~ ( )
 Here the precedence increases to the right, `==' `!=' `=~' and `!~',
 `<=' `>=' `<' and `>', `<<' and `>>', `+' and `-', `*' `/' and `%'
 being, in groups, at the same level. The `==' `!=' `=~' and `!~' oper-
 ators compare their arguments as strings; all others operate on num-
 bers. The operators `=~' and `!~' are like `!=' and `==' except that
 the right hand side is a glob-pattern (see Filename substitution)
 against which the left hand operand is matched. This reduces the need
 for use of the switch builtin command in shell scripts when all that is
 really needed is pattern matching.
 Null or missing arguments are considered `0'. The results of all
 expressions are strings, which represent decimal numbers. It is impor-
 tant to note that no two components of an expression can appear in the
 same word; except when adjacent to components of expressions which are
 syntactically significant to the parser (`&' `|' `<' `>' `(' `)') they
 should be surrounded by spaces.
 Command exit status
 Commands can be executed in expressions and their exit status returned
 by enclosing them in braces (`{}'). Remember that the braces should be
 separated from the words of the command by spaces. Command executions
 succeed, returning true, i.e., `1', if the command exits with status 0,
 otherwise they fail, returning false, i.e., `0'. If more detailed sta-
 tus information is required then the command should be executed outside
 of an expression and the status shell variable examined.
 File inquiry operators
 Some of these operators perform true/false tests on files and related
 objects. They are of the form -op file, where op is one of
 r Read access
 w Write access
 x Execute access
 X Executable in the path or shell builtin, e.g., `-X ls' and `-X
 ls-F' are generally true, but `-X /bin/ls' is not (+)
 e Existence
 o Ownership
 z Zero size
 s Non-zero size (+)
 f Plain file
 d Directory
 l Symbolic link (+) *
 b Block special file (+)
 c Character special file (+)
 p Named pipe (fifo) (+) *
 S Socket special file (+) *
 u Set-user-ID bit is set (+)
 g Set-group-ID bit is set (+)
 k Sticky bit is set (+)
 t file (which must be a digit) is an open file descriptor for a
 terminal device (+)
 R Has been migrated (convex only) (+)
 L Applies subsequent operators in a multiple-operator test to a
 symbolic link rather than to the file to which the link points
 (+) *
 file is command and filename expanded and then tested to see if it has
 the specified relationship to the real user. If file does not exist or
 is inaccessible or, for the operators indicated by `*', if the speci-
 fied file type does not exist on the current system, then all enquiries
 return false, i.e., `0'.
 These operators may be combined for conciseness: `-xy file' is equiva-
 lent to `-x file && -y file'. (+) For example, `-fx' is true (returns
 `1') for plain executable files, but not for directories.
 L may be used in a multiple-operator test to apply subsequent operators
 to a symbolic link rather than to the file to which the link points.
 For example, `-lLo' is true for links owned by the invoking user. Lr,
 Lw and Lx are always true for links and false for non-links. L has a
 different meaning when it is the last operator in a multiple-operator
 test; see below.
 It is possible but not useful, and sometimes misleading, to combine
 operators which expect file to be a file with operators which do not,
 (e.g., X and t). Following L with a non-file operator can lead to par-
 ticularly strange results.
 Other operators return other information, i.e., not just `0' or `1'.
 (+) They have the same format as before; op may be one of
 A Last file access time, as the number of seconds since the
 epoch
 A: Like A, but in timestamp format, e.g., `Fri May 14 16:36:10
 1993'
 M Last file modification time
 M: Like M, but in timestamp format
 C Last inode modification time
 C: Like C, but in timestamp format
 D Device number
 I Inode number
 F Composite file identifier, in the form device:inode
 L The name of the file pointed to by a symbolic link
 N Number of (hard) links
 P Permissions, in octal, without leading zero
 P: Like P, with leading zero
 Pmode Equivalent to `-P file & mode', e.g., `-P22 file' returns
 `22' if file is writable by group and other, `20' if by
 group only, and `0' if by neither
 Pmode: Like Pmode:, with leading zero
 U Numeric userid
 U: Username, or the numeric userid if the username is unknown
 G Numeric groupid
 G: Groupname, or the numeric groupid if the groupname is
 unknown
 Z Size, in bytes
 Only one of these operators may appear in a multiple-operator test, and
 it must be the last. Note that L has a different meaning at the end of
 and elsewhere in a multiple-operator test. Because `0' is a valid
 return value for many of these operators, they do not return `0' when
 they fail: most return `-1', and F returns `:'.
 If the shell is compiled with POSIX defined (see the version shell
 variable), the result of a file inquiry is based on the permission bits
 of the file and not on the result of the access(2)  system call. For
 example, if one tests a file with -w whose permissions would ordinarily
 allow writing but which is on a file system mounted read-only, the test
 will succeed in a POSIX shell but fail in a non-POSIX shell.
 File inquiry operators can also be evaluated with the filetest builtin
 command (q.v.) (+).
 Jobs
 The shell associates a job with each pipeline. It keeps a table of
 current jobs, printed by the jobs command, and assigns them small inte-
 ger numbers. When a job is started asynchronously with `&', the shell
 prints a line which looks like
 [1] 1234
 indicating that the job which was started asynchronously was job number
 1 and had one (top-level) process, whose process id was 1234.
 If you are running a job and wish to do something else you may hit the
 suspend key (usually `^Z'), which sends a STOP signal to the current
 job. The shell will then normally indicate that the job has been `Sus-
 pended' and print another prompt. If the listjobs shell variable is
 set, all jobs will be listed like the jobs builtin command; if it is
 set to `long' the listing will be in long format, like `jobs -l'. You
 can then manipulate the state of the suspended job. You can put it in
 the ``background'' with the bg command or run some other commands and
 eventually bring the job back into the ``foreground'' with fg. (See
 also the run-fg-editor editor command.) A `^Z' takes effect immedi-
 ately and is like an interrupt in that pending output and unread input
 are discarded when it is typed. The wait builtin command causes the
 shell to wait for all background jobs to complete.
 The `^]' key sends a delayed suspend signal, which does not generate a
 STOP signal until a program attempts to read(2)  it, to the current job.
 This can usefully be typed ahead when you have prepared some commands
 for a job which you wish to stop after it has read them. The `^Y' key
 performs this function in csh(1) ; in tcsh, `^Y' is an editing command.
 (+)
 A job being run in the background stops if it tries to read from the
 terminal. Background jobs are normally allowed to produce output, but
 this can be disabled by giving the command `stty tostop'. If you set
 this tty option, then background jobs will stop when they try to pro-
 duce output like they do when they try to read input.
 There are several ways to refer to jobs in the shell. The character
 `%' introduces a job name. If you wish to refer to job number 1, you
 can name it as `%1'. Just naming a job brings it to the foreground;
 thus `%1' is a synonym for `fg %1', bringing job 1 back into the fore-
 ground. Similarly, saying `%1 &' resumes job 1 in the background, just
 like `bg %1'. A job can also be named by an unambiguous prefix of the
 string typed in to start it: `%ex' would normally restart a suspended
 ex(1)  job, if there were only one suspended job whose name began with
 the string `ex'. It is also possible to say `%?string' to specify a
 job whose text contains string, if there is only one such job.
 The shell maintains a notion of the current and previous jobs. In out-
 put pertaining to jobs, the current job is marked with a `+' and the
 previous job with a `-'. The abbreviations `%+', `%', and (by analogy
 with the syntax of the history mechanism) `%%' all refer to the current
 job, and `%-' refers to the previous job.
 The job control mechanism requires that the stty(1)  option `new' be set
 on some systems. It is an artifact from a `new' implementation of the
 tty driver which allows generation of interrupt characters from the
 keyboard to tell jobs to stop. See stty(1)  and the setty builtin com-
 mand for details on setting options in the new tty driver.
 Status reporting
 The shell learns immediately whenever a process changes state. It nor-
 mally informs you whenever a job becomes blocked so that no further
 progress is possible, but only right before it prints a prompt. This
 is done so that it does not otherwise disturb your work. If, however,
 you set the shell variable notify, the shell will notify you immedi-
 ately of changes of status in background jobs. There is also a shell
 command notify which marks a single process so that its status changes
 will be immediately reported. By default notify marks the current
 process; simply say `notify' after starting a background job to mark
 it.
 When you try to leave the shell while jobs are stopped, you will be
 warned that `You have stopped jobs.' You may use the jobs command to
 see what they are. If you do this or immediately try to exit again,
 the shell will not warn you a second time, and the suspended jobs will
 be terminated.
 Automatic, periodic and timed events (+)
 There are various ways to run commands and take other actions automati-
 cally at various times in the ``life cycle'' of the shell. They are
 summarized here, and described in detail under the appropriate Builtin
 commands, Special shell variables and Special aliases.
 The sched builtin command puts commands in a scheduled-event list, to
 be executed by the shell at a given time.
 The beepcmd, cwdcmd, periodic, precmd, postcmd, and jobcmd Special
 aliases can be set, respectively, to execute commands when the shell
 wants to ring the bell, when the working directory changes, every tpe-
 riod minutes, before each prompt, before each command gets executed,
 after each command gets executed, and when a job is started or is
 brought into the foreground.
 The autologout shell variable can be set to log out or lock the shell
 after a given number of minutes of inactivity.
 The mail shell variable can be set to check for new mail periodically.
 The printexitvalue shell variable can be set to print the exit status
 of commands which exit with a status other than zero.
 The rmstar shell variable can be set to ask the user, when `rm *' is
 typed, if that is really what was meant.
 The time shell variable can be set to execute the time builtin command
 after the completion of any process that takes more than a given number
 of CPU seconds.
 The watch and who shell variables can be set to report when selected
 users log in or out, and the log builtin command reports on those users
 at any time.
 Native Language System support (+)
 The shell is eight bit clean (if so compiled; see the version shell
 variable) and thus supports character sets needing this capability.
 NLS support differs depending on whether or not the shell was compiled
 to use the system's NLS (again, see version). In either case, 7-bit
 ASCII is the default character code (e.g., the classification of which
 characters are printable) and sorting, and changing the LANG or
 LC_CTYPE environment variables causes a check for possible changes in
 these respects.
 When using the system's NLS, the setlocale(3)  function is called to
 determine appropriate character code/classification and sorting (e.g.,
 a 'en_CA.UTF-8' would yield "UTF-8" as a character code). This func-
 tion typically examines the LANG and LC_CTYPE environment variables;
 refer to the system documentation for further details. When not using
 the system's NLS, the shell simulates it by assuming that the ISO
 8859-1 character set is used whenever either of the LANG and LC_CTYPE
 variables are set, regardless of their values. Sorting is not affected
 for the simulated NLS.
 In addition, with both real and simulated NLS, all printable characters
 in the range 200円-377,円 i.e., those that have M-char bindings, are
 automatically rebound to self-insert-command. The corresponding bind-
 ing for the escape-char sequence, if any, is left alone. These charac-
 ters are not rebound if the NOREBIND environment variable is set. This
 may be useful for the simulated NLS or a primitive real NLS which
 assumes full ISO 8859-1. Otherwise, all M-char bindings in the range
 240円-377円 are effectively undone. Explicitly rebinding the relevant
 keys with bindkey is of course still possible.
 Unknown characters (i.e., those that are neither printable nor control
 characters) are printed in the format \nnn. If the tty is not in 8 bit
 mode, other 8 bit characters are printed by converting them to ASCII
 and using standout mode. The shell never changes the 7/8 bit mode of
 the tty and tracks user-initiated changes of 7/8 bit mode. NLS users
 (or, for that matter, those who want to use a meta key) may need to
 explicitly set the tty in 8 bit mode through the appropriate stty(1) 
 command in, e.g., the ~/.login file.
 OS variant support (+)
 A number of new builtin commands are provided to support features in
 particular operating systems. All are described in detail in the
 Builtin commands section.
 On systems that support TCF (aix-ibm370, aix-ps2), getspath and
 setspath get and set the system execution path, getxvers and setxvers
 get and set the experimental version prefix and migrate migrates pro-
 cesses between sites. The jobs builtin prints the site on which each
 job is executing.
 Under BS2000, bs2cmd executes commands of the underlying BS2000/OSD
 operating system.
 Under Domain/OS, inlib adds shared libraries to the current environ-
 ment, rootnode changes the rootnode and ver changes the systype.
 Under Mach, setpath is equivalent to Mach's setpath(1).
 Under Masscomp/RTU and Harris CX/UX, universe sets the universe.
 Under Harris CX/UX, ucb or att runs a command under the specified uni-
 verse.
 Under Convex/OS, warp prints or sets the universe.
 The VENDOR, OSTYPE and MACHTYPE environment variables indicate respec-
 tively the vendor, operating system and machine type (microprocessor
 class or machine model) of the system on which the shell thinks it is
 running. These are particularly useful when sharing one's home direc-
 tory between several types of machines; one can, for example,
 set path = (~/bin.$MACHTYPE /usr/ucb /bin /usr/bin .)
 in one's ~/.login and put executables compiled for each machine in the
 appropriate directory.
 The version shell variable indicates what options were chosen when the
 shell was compiled.
 Note also the newgrp builtin, the afsuser and echo_style shell vari-
 ables and the system-dependent locations of the shell's input files
 (see FILES).
 Signal handling
 Login shells ignore interrupts when reading the file ~/.logout. The
 shell ignores quit signals unless started with -q. Login shells catch
 the terminate signal, but non-login shells inherit the terminate behav-
 ior from their parents. Other signals have the values which the shell
 inherited from its parent.
 In shell scripts, the shell's handling of interrupt and terminate sig-
 nals can be controlled with onintr, and its handling of hangups can be
 controlled with hup and nohup.
 The shell exits on a hangup (see also the logout shell variable). By
 default, the shell's children do too, but the shell does not send them
 a hangup when it exits. hup arranges for the shell to send a hangup to
 a child when it exits, and nohup sets a child to ignore hangups.
 Terminal management (+)
 The shell uses three different sets of terminal (``tty'') modes:
 `edit', used when editing, `quote', used when quoting literal charac-
 ters, and `execute', used when executing commands. The shell holds
 some settings in each mode constant, so commands which leave the tty in
 a confused state do not interfere with the shell. The shell also
 matches changes in the speed and padding of the tty. The list of tty
 modes that are kept constant can be examined and modified with the
 setty builtin. Note that although the editor uses CBREAK mode (or its
 equivalent), it takes typed-ahead characters anyway.
 The echotc, settc and telltc commands can be used to manipulate and
 debug terminal capabilities from the command line.
 On systems that support SIGWINCH or SIGWINDOW, the shell adapts to win-
 dow resizing automatically and adjusts the environment variables LINES
 and COLUMNS if set. If the environment variable TERMCAP contains li#
 and co# fields, the shell adjusts them to reflect the new window size.

REFERENCE

 The next sections of this manual describe all of the available Builtin
 commands, Special aliases and Special shell variables.
 Builtin commands
 %job A synonym for the fg builtin command.
 %job & A synonym for the bg builtin command.
 : Does nothing, successfully.
 @
 @ name = expr
 @ name[index] = expr
 @ name++|--
 @ name[index]++|--
 The first form prints the values of all shell variables.
 The second form assigns the value of expr to name. The third
 form assigns the value of expr to the index'th component of
 name; both name and its index'th component must already exist.
 expr may contain the operators `*', `+', etc., as in C. If
 expr contains `<', `>', `&' or `' then at least that part of
 expr must be placed within `()'. Note that the syntax of expr
 has nothing to do with that described under Expressions.
 The fourth and fifth forms increment (`++') or decrement (`--')
 name or its index'th component.
 The space between `@' and name is required. The spaces between
 name and `=' and between `=' and expr are optional. Components
 of expr must be separated by spaces.
 alias [name [wordlist]]
 Without arguments, prints all aliases. With name, prints the
 alias for name. With name and wordlist, assigns wordlist as
 the alias of name. wordlist is command and filename substi-
 tuted. name may not be `alias' or `unalias'. See also the
 unalias builtin command.
 alloc Shows the amount of dynamic memory acquired, broken down into
 used and free memory. With an argument shows the number of
 free and used blocks in each size category. The categories
 start at size 8 and double at each step. This command's output
 may vary across system types, because systems other than the
 VAX may use a different memory allocator.
 bg [%job ...]
 Puts the specified jobs (or, without arguments, the current
 job) into the background, continuing each if it is stopped.
 job may be a number, a string, `', `%', `+' or `-' as described
 under Jobs.
 bindkey [-l|-d|-e|-v|-u] (+)
 bindkey [-a] [-b] [-k] [-r] [--] key (+)
 bindkey [-a] [-b] [-k] [-c|-s] [--] key command (+)
 Without options, the first form lists all bound keys and the
 editor command to which each is bound, the second form lists
 the editor command to which key is bound and the third form
 binds the editor command command to key. Options include:
 -l Lists all editor commands and a short description of each.
 -d Binds all keys to the standard bindings for the default
 editor.
 -e Binds all keys to the standard GNU Emacs-like bindings.
 -v Binds all keys to the standard vi(1) -like bindings.
 -a Lists or changes key-bindings in the alternative key map.
 This is the key map used in vi command mode.
 -b key is interpreted as a control character written ^charac-
 ter (e.g., `^A') or C-character (e.g., `C-A'), a meta char-
 acter written M-character (e.g., `M-A'), a function key
 written F-string (e.g., `F-string'), or an extended prefix
 key written X-character (e.g., `X-A').
 -k key is interpreted as a symbolic arrow key name, which may
 be one of `down', `up', `left' or `right'.
 -r Removes key's binding. Be careful: `bindkey -r' does not
 bind key to self-insert-command (q.v.), it unbinds key com-
 pletely.
 -c command is interpreted as a builtin or external command
 instead of an editor command.
 -s command is taken as a literal string and treated as termi-
 nal input when key is typed. Bound keys in command are
 themselves reinterpreted, and this continues for ten levels
 of interpretation.
 -- Forces a break from option processing, so the next word is
 taken as key even if it begins with '-'.
 -u (or any invalid option)
 Prints a usage message.
 key may be a single character or a string. If a command is
 bound to a string, the first character of the string is bound
 to sequence-lead-in and the entire string is bound to the com-
 mand.
 Control characters in key can be literal (they can be typed by
 preceding them with the editor command quoted-insert, normally
 bound to `^V') or written caret-character style, e.g., `^A'.
 Delete is written `^?' (caret-question mark). key and command
 can contain backslashed escape sequences (in the style of Sys-
 tem V echo(1) ) as follows:
 \a Bell
 \b Backspace
 \e Escape
 \f Form feed
 \n Newline
 \r Carriage return
 \t Horizontal tab
 \v Vertical tab
 \nnn The ASCII character corresponding to the octal num-
 ber nnn
 `\' nullifies the special meaning of the following character,
 if it has any, notably `\' and `^'.
 bs2cmd bs2000-command (+)
 Passes bs2000-command to the BS2000 command interpreter for
 execution. Only non-interactive commands can be executed, and
 it is not possible to execute any command that would overlay
 the image of the current process, like /EXECUTE or /CALL-PROCE-
 DURE. (BS2000 only)
 break Causes execution to resume after the end of the nearest enclos-
 ing foreach or while. The remaining commands on the current
 line are executed. Multi-level breaks are thus possible by
 writing them all on one line.
 breaksw Causes a break from a switch, resuming after the endsw.
 builtins (+)
 Prints the names of all builtin commands.
 bye (+) A synonym for the logout builtin command. Available only if
 the shell was so compiled; see the version shell variable.
 case label:
 A label in a switch statement as discussed below.
 cd [-p] [-l] [-n|-v] [name]
 If a directory name is given, changes the shell's working
 directory to name. If not, changes to home. If name is `-' it
 is interpreted as the previous working directory (see Other
 substitutions). (+) If name is not a subdirectory of the cur-
 rent directory (and does not begin with `/', `./' or `../'),
 each component of the variable cdpath is checked to see if it
 has a subdirectory name. Finally, if all else fails but name
 is a shell variable whose value begins with `/', then this is
 tried to see if it is a directory.
 With -p, prints the final directory stack, just like dirs. The
 -l, -n and -v flags have the same effect on cd as on dirs, and
 they imply -p. (+)
 See also the implicitcd shell variable.
 chdir A synonym for the cd builtin command.
 complete [command [word/pattern/list[:select]/[[suffix]/] ...]] (+)
 Without arguments, lists all completions. With command, lists
 completions for command. With command and word etc., defines
 completions.
 command may be a full command name or a glob-pattern (see File-
 name substitution). It can begin with `-' to indicate that
 completion should be used only when command is ambiguous.
 word specifies which word relative to the current word is to be
 completed, and may be one of the following:
 c Current-word completion. pattern is a glob-pattern
 which must match the beginning of the current word on
 the command line. pattern is ignored when completing
 the current word.
 C Like c, but includes pattern when completing the cur-
 rent word.
 n Next-word completion. pattern is a glob-pattern which
 must match the beginning of the previous word on the
 command line.
 N Like n, but must match the beginning of the word two
 before the current word.
 p Position-dependent completion. pattern is a numeric
 range, with the same syntax used to index shell vari-
 ables, which must include the current word.
 list, the list of possible completions, may be one of the fol-
 lowing:
 a Aliases
 b Bindings (editor commands)
 c Commands (builtin or external commands)
 C External commands which begin with the supplied
 path prefix
 d Directories
 D Directories which begin with the supplied path pre-
 fix
 e Environment variables
 f Filenames
 F Filenames which begin with the supplied path prefix
 g Groupnames
 j Jobs
 l Limits
 n Nothing
 s Shell variables
 S Signals
 t Plain (``text'') files
 T Plain (``text'') files which begin with the sup-
 plied path prefix
 v Any variables
 u Usernames
 x Like n, but prints select when list-choices is
 used.
 X Completions
 $var Words from the variable var
 (...) Words from the given list
 `...` Words from the output of command
 select is an optional glob-pattern. If given, words from only
 list that match select are considered and the fignore shell
 variable is ignored. The last three types of completion may
 not have a select pattern, and x uses select as an explanatory
 message when the list-choices editor command is used.
 suffix is a single character to be appended to a successful
 completion. If null, no character is appended. If omitted (in
 which case the fourth delimiter can also be omitted), a slash
 is appended to directories and a space to other words.
 Now for some examples. Some commands take only directories as
 arguments, so there's no point completing plain files.
 > complete cd 'p/1/d/'
 completes only the first word following `cd' (`p/1') with a
 directory. p-type completion can also be used to narrow down
 command completion:
 > co[^D]
 complete compress
 > complete -co* 'p/0/(compress)/'
 > co[^D]
 > compress
 This completion completes commands (words in position 0, `p/0')
 which begin with `co' (thus matching `co*') to `compress' (the
 only word in the list). The leading `-' indicates that this
 completion is to be used with only ambiguous commands.
 > complete find 'n/-user/u/'
 is an example of n-type completion. Any word following `find'
 and immediately following `-user' is completed from the list of
 users.
 > complete cc 'c/-I/d/'
 demonstrates c-type completion. Any word following `cc' and
 beginning with `-I' is completed as a directory. `-I' is not
 taken as part of the directory because we used lowercase c.
 Different lists are useful with different commands.
 > complete alias 'p/1/a/'
 > complete man 'p/*/c/'
 > complete set 'p/1/s/'
 > complete true 'p/1/x:Truth has no options./'
 These complete words following `alias' with aliases, `man' with
 commands, and `set' with shell variables. `true' doesn't have
 any options, so x does nothing when completion is attempted and
 prints `Truth has no options.' when completion choices are
 listed.
 Note that the man example, and several other examples below,
 could just as well have used 'c/*' or 'n/*' as 'p/*'.
 Words can be completed from a variable evaluated at completion
 time,
 > complete ftp 'p/1/$hostnames/'
 > set hostnames = (rtfm.mit.edu tesla.ee.cornell.edu)
 > ftp [^D]
 rtfm.mit.edu tesla.ee.cornell.edu
 > ftp [^C]
 > set hostnames = (rtfm.mit.edu tesla.ee.cornell.edu
 uunet.uu.net)
 > ftp [^D]
 rtfm.mit.edu tesla.ee.cornell.edu uunet.uu.net
 or from a command run at completion time:
 > complete kill 'p/*/`ps | awk \{print\ \1ドル\}`/'
 > kill -9 [^D]
 23113 23377 23380 23406 23429 23529 23530 PID
 Note that the complete command does not itself quote its argu-
 ments, so the braces, space and `$' in `{print 1ドル}' must be
 quoted explicitly.
 One command can have multiple completions:
 > complete dbx 'p/2/(core)/' 'p/*/c/'
 completes the second argument to `dbx' with the word `core' and
 all other arguments with commands. Note that the positional
 completion is specified before the next-word completion.
 Because completions are evaluated from left to right, if the
 next-word completion were specified first it would always match
 and the positional completion would never be executed. This is
 a common mistake when defining a completion.
 The select pattern is useful when a command takes files with
 only particular forms as arguments. For example,
 > complete cc 'p/*/f:*.[cao]/'
 completes `cc' arguments to files ending in only `.c', `.a', or
 `.o'. select can also exclude files, using negation of a glob-
 pattern as described under Filename substitution. One might
 use
 > complete rm 'p/*/f:^*.{c,h,cc,C,tex,1,man,l,y}/'
 to exclude precious source code from `rm' completion. Of
 course, one could still type excluded names manually or over-
 ride the completion mechanism using the complete-word-raw or
 list-choices-raw editor commands (q.v.).
 The `C', `D', `F' and `T' lists are like `c', `d', `f' and `t'
 respectively, but they use the select argument in a different
 way: to restrict completion to files beginning with a particu-
 lar path prefix. For example, the Elm mail program uses `=' as
 an abbreviation for one's mail directory. One might use
 > complete elm c@=@F:$HOME/Mail/@
 to complete `elm -f =' as if it were `elm -f ~/Mail/'. Note
 that we used `@' instead of `/' to avoid confusion with the
 select argument, and we used `$HOME' instead of `~' because
 home directory substitution works at only the beginning of a
 word.
 suffix is used to add a nonstandard suffix (not space or `/'
 for directories) to completed words.
 > complete finger 'c/*@/$hostnames/' 'p/1/u/@'
 completes arguments to `finger' from the list of users, appends
 an `@', and then completes after the `@' from the `hostnames'
 variable. Note again the order in which the completions are
 specified.
 Finally, here's a complex example for inspiration:
 > complete find \
 'n/-name/f/' 'n/-newer/f/' 'n/-{,n}cpio/f/' \
 'n/-exec/c/' 'n/-ok/c/' 'n/-user/u/' \
 'n/-group/g/' 'n/-fstype/(nfs 4.2)/' \
 'n/-type/(b c d f l p s)/' \
 'c/-/(name newer cpio ncpio exec ok user \
 group fstype type atime ctime depth inum \
 ls mtime nogroup nouser perm print prune \
 size xdev)/' \
 'p/*/d/'
 This completes words following `-name', `-newer', `-cpio' or
 `ncpio' (note the pattern which matches both) to files, words
 following `-exec' or `-ok' to commands, words following `user'
 and `group' to users and groups respectively and words follow-
 ing `-fstype' or `-type' to members of the given lists. It
 also completes the switches themselves from the given list
 (note the use of c-type completion) and completes anything not
 otherwise completed to a directory. Whew.
 Remember that programmed completions are ignored if the word
 being completed is a tilde substitution (beginning with `~') or
 a variable (beginning with `$'). complete is an experimental
 feature, and the syntax may change in future versions of the
 shell. See also the uncomplete builtin command.
 continue
 Continues execution of the nearest enclosing while or foreach.
 The rest of the commands on the current line are executed.
 default:
 Labels the default case in a switch statement. It should come
 after all case labels.
 dirs [-l] [-n|-v]
 dirs -S|-L [filename] (+)
 dirs -c (+)
 The first form prints the directory stack. The top of the
 stack is at the left and the first directory in the stack is
 the current directory. With -l, `~' or `~name' in the output
 is expanded explicitly to home or the pathname of the home
 directory for user name. (+) With -n, entries are wrapped
 before they reach the edge of the screen. (+) With -v, entries
 are printed one per line, preceded by their stack positions.
 (+) If more than one of -n or -v is given, -v takes precedence.
 -p is accepted but does nothing.
 With -S, the second form saves the directory stack to filename
 as a series of cd and pushd commands. With -L, the shell
 sources filename, which is presumably a directory stack file
 saved by the -S option or the savedirs mechanism. In either
 case, dirsfile is used if filename is not given and ~/.cshdirs
 is used if dirsfile is unset.
 Note that login shells do the equivalent of `dirs -L' on
 startup and, if savedirs is set, `dirs -S' before exiting.
 Because only ~/.tcshrc is normally sourced before ~/.cshdirs,
 dirsfile should be set in ~/.tcshrc rather than ~/.login.
 The last form clears the directory stack.
 echo [-n] word ...
 Writes each word to the shell's standard output, separated by
 spaces and terminated with a newline. The echo_style shell
 variable may be set to emulate (or not) the flags and escape
 sequences of the BSD and/or System V versions of echo; see
 echo(1) .
 echotc [-sv] arg ... (+)
 Exercises the terminal capabilities (see termcap(5)) in args.
 For example, 'echotc home' sends the cursor to the home posi-
 tion, 'echotc cm 3 10' sends it to column 3 and row 10, and
 'echotc ts 0; echo "This is a test."; echotc fs' prints "This
 is a test." in the status line.
 If arg is 'baud', 'cols', 'lines', 'meta' or 'tabs', prints the
 value of that capability ("yes" or "no" indicating that the
 terminal does or does not have that capability). One might use
 this to make the output from a shell script less verbose on
 slow terminals, or limit command output to the number of lines
 on the screen:
 > set history=`echotc lines`
 > @ history--
 Termcap strings may contain wildcards which will not echo cor-
 rectly. One should use double quotes when setting a shell
 variable to a terminal capability string, as in the following
 example that places the date in the status line:
 > set tosl="`echotc ts 0`"
 > set frsl="`echotc fs`"
 > echo -n "$tosl";date; echo -n "$frsl"
 With -s, nonexistent capabilities return the empty string
 rather than causing an error. With -v, messages are verbose.
 else
 end
 endif
 endsw See the description of the foreach, if, switch, and while
 statements below.
 eval arg ...
 Treats the arguments as input to the shell and executes the
 resulting command(s) in the context of the current shell. This
 is usually used to execute commands generated as the result of
 command or variable substitution, because parsing occurs before
 these substitutions. See tset(1)  for a sample use of eval.
 exec command
 Executes the specified command in place of the current shell.
 exit [expr]
 The shell exits either with the value of the specified expr (an
 expression, as described under Expressions) or, without expr,
 with the value 0.
 fg [%job ...]
 Brings the specified jobs (or, without arguments, the current
 job) into the foreground, continuing each if it is stopped.
 job may be a number, a string, `', `%', `+' or `-' as described
 under Jobs. See also the run-fg-editor editor command.
 filetest -op file ... (+)
 Applies op (which is a file inquiry operator as described under
 File inquiry operators) to each file and returns the results as
 a space-separated list.
 foreach name (wordlist)
 ...
 end Successively sets the variable name to each member of wordlist
 and executes the sequence of commands between this command and
 the matching end. (Both foreach and end must appear alone on
 separate lines.) The builtin command continue may be used to
 continue the loop prematurely and the builtin command break to
 terminate it prematurely. When this command is read from the
 terminal, the loop is read once prompting with `foreach? ' (or
 prompt2) before any statements in the loop are executed. If
 you make a mistake typing in a loop at the terminal you can rub
 it out.
 getspath (+)
 Prints the system execution path. (TCF only)
 getxvers (+)
 Prints the experimental version prefix. (TCF only)
 glob wordlist
 Like echo, but the `-n' parameter is not recognized and words
 are delimited by null characters in the output. Useful for
 programs which wish to use the shell to filename expand a list
 of words.
 goto word
 word is filename and command-substituted to yield a string of
 the form `label'. The shell rewinds its input as much as pos-
 sible, searches for a line of the form `label:', possibly pre-
 ceded by blanks or tabs, and continues execution after that
 line.
 hashstat
 Prints a statistics line indicating how effective the internal
 hash table has been at locating commands (and avoiding exec's).
 An exec is attempted for each component of the path where the
 hash function indicates a possible hit, and in each component
 which does not begin with a `/'.
 On machines without vfork(2) , prints only the number and size
 of hash buckets.
 history [-hTr] [n]
 history -S|-L|-M [filename] (+)
 history -c (+)
 The first form prints the history event list. If n is given
 only the n most recent events are printed or saved. With -h,
 the history list is printed without leading numbers. If -T is
 specified, timestamps are printed also in comment form. (This
 can be used to produce files suitable for loading with 'history
 -L' or 'source -h'.) With -r, the order of printing is most
 recent first rather than oldest first.
 With -S, the second form saves the history list to filename.
 If the first word of the savehist shell variable is set to a
 number, at most that many lines are saved. If the second word
 of savehist is set to `merge', the history list is merged with
 the existing history file instead of replacing it (if there is
 one) and sorted by time stamp. (+) Merging is intended for an
 environment like the X Window System with several shells in
 simultaneous use. Currently it succeeds only when the shells
 quit nicely one after another.
 With -L, the shell appends filename, which is presumably a his-
 tory list saved by the -S option or the savehist mechanism, to
 the history list. -M is like -L, but the contents of filename
 are merged into the history list and sorted by timestamp. In
 either case, histfile is used if filename is not given and
 ~/.history is used if histfile is unset. `history -L' is
 exactly like 'source -h' except that it does not require a
 filename.
 Note that login shells do the equivalent of `history -L' on
 startup and, if savehist is set, `history -S' before exiting.
 Because only ~/.tcshrc is normally sourced before ~/.history,
 histfile should be set in ~/.tcshrc rather than ~/.login.
 If histlit is set, the first and second forms print and save
 the literal (unexpanded) form of the history list.
 The last form clears the history list.
 hup [command] (+)
 With command, runs command such that it will exit on a hangup
 signal and arranges for the shell to send it a hangup signal
 when the shell exits. Note that commands may set their own
 response to hangups, overriding hup. Without an argument
 (allowed in only a shell script), causes the shell to exit on a
 hangup for the remainder of the script. See also Signal han-
 dling and the nohup builtin command.
 if (expr) command
 If expr (an expression, as described under Expressions) evalu-
 ates true, then command is executed. Variable substitution on
 command happens early, at the same time it does for the rest of
 the if command. command must be a simple command, not an
 alias, a pipeline, a command list or a parenthesized command
 list, but it may have arguments. Input/output redirection
 occurs even if expr is false and command is thus not executed;
 this is a bug.
 if (expr) then
 ...
 else if (expr2) then
 ...
 else
 ...
 endif If the specified expr is true then the commands to the first
 else are executed; otherwise if expr2 is true then the commands
 to the second else are executed, etc. Any number of else-if
 pairs are possible; only one endif is needed. The else part is
 likewise optional. (The words else and endif must appear at
 the beginning of input lines; the if must appear alone on its
 input line or after an else.)
 inlib shared-library ... (+)
 Adds each shared-library to the current environment. There is
 no way to remove a shared library. (Domain/OS only)
 jobs [-l]
 Lists the active jobs. With -l, lists process IDs in addition
 to the normal information. On TCF systems, prints the site on
 which each job is executing.
 kill [-s signal] %job|pid ...
 kill -l The first and second forms sends the specified signal (or, if
 none is given, the TERM (terminate) signal) to the specified
 jobs or processes. job may be a number, a string, `', `%', `+'
 or `-' as described under Jobs. Signals are either given by
 number or by name (as given in /usr/include/signal.h, stripped
 of the prefix `SIG'). There is no default job; saying just
 `kill' does not send a signal to the current job. If the sig-
 nal being sent is TERM (terminate) or HUP (hangup), then the
 job or process is sent a CONT (continue) signal as well. The
 third form lists the signal names.
 limit [-h] [resource [maximum-use]]
 Limits the consumption by the current process and each process
 it creates to not individually exceed maximum-use on the speci-
 fied resource. If no maximum-use is given, then the current
 limit is printed; if no resource is given, then all limitations
 are given. If the -h flag is given, the hard limits are used
 instead of the current limits. The hard limits impose a ceil-
 ing on the values of the current limits. Only the super-user
 may raise the hard limits, but a user may lower or raise the
 current limits within the legal range.
 Controllable resources currently include (if supported by the
 OS):
 cputime
 the maximum number of cpu-seconds to be used by each
 process
 filesize
 the largest single file which can be created
 datasize
 the maximum growth of the data+stack region via sbrk(2) 
 beyond the end of the program text
 stacksize
 the maximum size of the automatically-extended stack
 region
 coredumpsize
 the size of the largest core dump that will be created
 memoryuse
 the maximum amount of physical memory a process may have
 allocated to it at a given time
 heapsize
 the maximum amount of memory a process may allocate per
 brk() system call
 descriptors or openfiles
 the maximum number of open files for this process
 concurrency
 the maximum number of threads for this process
 memorylocked
 the maximum size which a process may lock into memory
 using mlock(2) 
 maxproc
 the maximum number of simultaneous processes for this
 user id
 sbsize the maximum size of socket buffer usage for this user
 maximum-use may be given as a (floating point or integer) num-
 ber followed by a scale factor. For all limits other than
 cputime the default scale is `k' or `kilobytes' (1024 bytes); a
 scale factor of `m' or `megabytes' may also be used. For
 cputime the default scaling is `seconds', while `m' for minutes
 or `h' for hours, or a time of the form `mm:ss' giving minutes
 and seconds may be used.
 For both resource names and scale factors, unambiguous prefixes
 of the names suffice.
 log (+) Prints the watch shell variable and reports on each user indi-
 cated in watch who is logged in, regardless of when they last
 logged in. See also watchlog.
 login Terminates a login shell, replacing it with an instance of
 /bin/login. This is one way to log off, included for compati-
 bility with sh(1) .
 logout Terminates a login shell. Especially useful if ignoreeof is
 set.
 ls-F [-switch ...] [file ...] (+)
 Lists files like `ls -F', but much faster. It identifies each
 type of special file in the listing with a special character:
 / Directory
 * Executable
 # Block device
 % Character device
 | Named pipe (systems with named pipes only)
 = Socket (systems with sockets only)
 @ Symbolic link (systems with symbolic links only)
 + Hidden directory (AIX only) or context dependent (HP/UX
 only)
 : Network special (HP/UX only)
 If the listlinks shell variable is set, symbolic links are
 identified in more detail (on only systems that have them, of
 course):
 @ Symbolic link to a non-directory
 > Symbolic link to a directory
 & Symbolic link to nowhere
 listlinks also slows down ls-F and causes partitions holding
 files pointed to by symbolic links to be mounted.
 If the listflags shell variable is set to `x', `a' or `A', or
 any combination thereof (e.g., `xA'), they are used as flags to
 ls-F, making it act like `ls -xF', `ls -Fa', `ls -FA' or a com-
 bination (e.g., `ls -FxA'). On machines where `ls -C' is not
 the default, ls-F acts like `ls -CF', unless listflags contains
 an `x', in which case it acts like `ls -xF'. ls-F passes its
 arguments to ls(1)  if it is given any switches, so `alias ls
 ls-F' generally does the right thing.
 The ls-F builtin can list files using different colors depend-
 ing on the filetype or extension. See the color tcsh variable
 and the LS_COLORS environment variable.
 migrate [-site] pid|%jobid ... (+)
 migrate -site (+)
 The first form migrates the process or job to the site speci-
 fied or the default site determined by the system path. The
 second form is equivalent to `migrate -site $$': it migrates
 the current process to the specified site. Migrating the shell
 itself can cause unexpected behavior, because the shell does
 not like to lose its tty. (TCF only)
 newgrp [-] group (+)
 Equivalent to `exec newgrp'; see newgrp(1) . Available only if
 the shell was so compiled; see the version shell variable.
 nice [+number] [command]
 Sets the scheduling priority for the shell to number, or, with-
 out number, to 4. With command, runs command at the appropri-
 ate priority. The greater the number, the less cpu the process
 gets. The super-user may specify negative priority by using
 `nice -number ...'. Command is always executed in a sub-shell,
 and the restrictions placed on commands in simple if statements
 apply.
 nohup [command]
 With command, runs command such that it will ignore hangup sig-
 nals. Note that commands may set their own response to
 hangups, overriding nohup. Without an argument (allowed in
 only a shell script), causes the shell to ignore hangups for
 the remainder of the script. See also Signal handling and the
 hup builtin command.
 notify [%job ...]
 Causes the shell to notify the user asynchronously when the
 status of any of the specified jobs (or, without %job, the cur-
 rent job) changes, instead of waiting until the next prompt as
 is usual. job may be a number, a string, `', `%', `+' or `-'
 as described under Jobs. See also the notify shell variable.
 onintr [-|label]
 Controls the action of the shell on interrupts. Without argu-
 ments, restores the default action of the shell on interrupts,
 which is to terminate shell scripts or to return to the termi-
 nal command input level. With `-', causes all interrupts to be
 ignored. With label, causes the shell to execute a `goto
 label' when an interrupt is received or a child process termi-
 nates because it was interrupted.
 onintr is ignored if the shell is running detached and in sys-
 tem startup files (see FILES), where interrupts are disabled
 anyway.
 popd [-p] [-l] [-n|-v] [+n]
 Without arguments, pops the directory stack and returns to the
 new top directory. With a number `+n', discards the n'th entry
 in the stack.
 Finally, all forms of popd print the final directory stack,
 just like dirs. The pushdsilent shell variable can be set to
 prevent this and the -p flag can be given to override pushdsi-
 lent. The -l, -n and -v flags have the same effect on popd as
 on dirs. (+)
 printenv [name] (+)
 Prints the names and values of all environment variables or,
 with name, the value of the environment variable name.
 pushd [-p] [-l] [-n|-v] [name|+n]
 Without arguments, exchanges the top two elements of the direc-
 tory stack. If pushdtohome is set, pushd without arguments
 does `pushd ~', like cd. (+) With name, pushes the current
 working directory onto the directory stack and changes to name.
 If name is `-' it is interpreted as the previous working direc-
 tory (see Filename substitution). (+) If dunique is set, pushd
 removes any instances of name from the stack before pushing it
 onto the stack. (+) With a number `+n', rotates the nth ele-
 ment of the directory stack around to be the top element and
 changes to it. If dextract is set, however, `pushd +n'
 extracts the nth directory, pushes it onto the top of the stack
 and changes to it. (+)
 Finally, all forms of pushd print the final directory stack,
 just like dirs. The pushdsilent shell variable can be set to
 prevent this and the -p flag can be given to override pushdsi-
 lent. The -l, -n and -v flags have the same effect on pushd as
 on dirs. (+)
 rehash Causes the internal hash table of the contents of the directo-
 ries in the path variable to be recomputed. This is needed if
 new commands are added to directories in path while you are
 logged in. This should be necessary only if you add commands
 to one of your own directories, or if a systems programmer
 changes the contents of one of the system directories. Also
 flushes the cache of home directories built by tilde expansion.
 repeat count command
 The specified command, which is subject to the same restric-
 tions as the command in the one line if statement above, is
 executed count times. I/O redirections occur exactly once,
 even if count is 0.
 rootnode //nodename (+)
 Changes the rootnode to //nodename, so that `/' will be inter-
 preted as `//nodename'. (Domain/OS only)
 sched (+)
 sched [+]hh:mm command (+)
 sched -n (+)
 The first form prints the scheduled-event list. The sched
 shell variable may be set to define the format in which the
 scheduled-event list is printed. The second form adds command
 to the scheduled-event list. For example,
 > sched 11:00 echo It\'s eleven o\'clock.
 causes the shell to echo `It's eleven o'clock.' at 11 AM. The
 time may be in 12-hour AM/PM format
 > sched 5pm set prompt='[%h] It\'s after 5; go home: >'
 or may be relative to the current time:
 > sched +2:15 /usr/lib/uucp/uucico -r1 -sother
 A relative time specification may not use AM/PM format. The
 third form removes item n from the event list:
 > sched
 1 Wed Apr 4 15:42 /usr/lib/uucp/uucico -r1 -sother
 2 Wed Apr 4 17:00 set prompt=[%h] It's after 5; go
 home: >
 > sched -2
 > sched
 1 Wed Apr 4 15:42 /usr/lib/uucp/uucico -r1 -sother
 A command in the scheduled-event list is executed just before
 the first prompt is printed after the time when the command is
 scheduled. It is possible to miss the exact time when the com-
 mand is to be run, but an overdue command will execute at the
 next prompt. A command which comes due while the shell is
 waiting for user input is executed immediately. However, nor-
 mal operation of an already-running command will not be inter-
 rupted so that a scheduled-event list element may be run.
 This mechanism is similar to, but not the same as, the at(1) 
 command on some Unix systems. Its major disadvantage is that
 it may not run a command at exactly the specified time. Its
 major advantage is that because sched runs directly from the
 shell, it has access to shell variables and other structures.
 This provides a mechanism for changing one's working environ-
 ment based on the time of day.
 set
 set name ...
 set name=word ...
 set [-r] [-f|-l] name=(wordlist) ... (+)
 set name[index]=word ...
 set -r (+)
 set -r name ... (+)
 set -r name=word ... (+)
 The first form of the command prints the value of all shell
 variables. Variables which contain more than a single word
 print as a parenthesized word list. The second form sets name
 to the null string. The third form sets name to the single
 word. The fourth form sets name to the list of words in
 wordlist. In all cases the value is command and filename
 expanded. If -r is specified, the value is set read-only. If
 -f or -l are specified, set only unique words keeping their
 order. -f prefers the first occurrence of a word, and -l the
 last. The fifth form sets the index'th component of name to
 word; this component must already exist. The sixth form lists
 only the names of all shell variables that are read-only. The
 seventh form makes name read-only, whether or not it has a
 value. The second form sets name to the null string. The
 eighth form is the same as the third form, but make name read-
 only at the same time.
 These arguments can be repeated to set and/or make read-only
 multiple variables in a single set command. Note, however,
 that variable expansion happens for all arguments before any
 setting occurs. Note also that `=' can be adjacent to both
 name and word or separated from both by whitespace, but cannot
 be adjacent to only one or the other. See also the unset
 builtin command.
 setenv [name [value]]
 Without arguments, prints the names and values of all environ-
 ment variables. Given name, sets the environment variable name
 to value or, without value, to the null string.
 setpath path (+)
 Equivalent to setpath(1). (Mach only)
 setspath LOCAL|site|cpu ... (+)
 Sets the system execution path. (TCF only)
 settc cap value (+)
 Tells the shell to believe that the terminal capability cap (as
 defined in termcap(5)) has the value value. No sanity checking
 is done. Concept terminal users may have to `settc xn no' to
 get proper wrapping at the rightmost column.
 setty [-d|-q|-x] [-a] [[+|-]mode] (+)
 Controls which tty modes (see Terminal management) the shell
 does not allow to change. -d, -q or -x tells setty to act on
 the `edit', `quote' or `execute' set of tty modes respectively;
 without -d, -q or -x, `execute' is used.
 Without other arguments, setty lists the modes in the chosen
 set which are fixed on (`+mode') or off (`-mode'). The avail-
 able modes, and thus the display, vary from system to system.
 With -a, lists all tty modes in the chosen set whether or not
 they are fixed. With +mode, -mode or mode, fixes mode on or
 off or removes control from mode in the chosen set. For exam-
 ple, `setty +echok echoe' fixes `echok' mode on and allows com-
 mands to turn `echoe' mode on or off, both when the shell is
 executing commands.
 setxvers [string] (+)
 Set the experimental version prefix to string, or removes it if
 string is omitted. (TCF only)
 shift [variable]
 Without arguments, discards argv[1] and shifts the members of
 argv to the left. It is an error for argv not to be set or to
 have less than one word as value. With variable, performs the
 same function on variable.
 source [-h] name [args ...]
 The shell reads and executes commands from name. The commands
 are not placed on the history list. If any args are given,
 they are placed in argv. (+) source commands may be nested; if
 they are nested too deeply the shell may run out of file
 descriptors. An error in a source at any level terminates all
 nested source commands. With -h, commands are placed on the
 history list instead of being executed, much like `history -L'.
 stop %job|pid ...
 Stops the specified jobs or processes which are executing in
 the background. job may be a number, a string, `', `%', `+' or
 `-' as described under Jobs. There is no default job; saying
 just `stop' does not stop the current job.
 suspend Causes the shell to stop in its tracks, much as if it had been
 sent a stop signal with ^Z. This is most often used to stop
 shells started by su(1) .
 switch (string)
 case str1:
 ...
 breaksw
 ...
 default:
 ...
 breaksw
 endsw Each case label is successively matched, against the specified
 string which is first command and filename expanded. The file
 metacharacters `*', `?' and `[...]' may be used in the case
 labels, which are variable expanded. If none of the labels
 match before a `default' label is found, then the execution
 begins after the default label. Each case label and the
 default label must appear at the beginning of a line. The com-
 mand breaksw causes execution to continue after the endsw.
 Otherwise control may fall through case labels and default
 labels as in C. If no label matches and there is no default,
 execution continues after the endsw.
 telltc (+)
 Lists the values of all terminal capabilities (see termcap(5)).
 termname [terminal type] (+)
 Tests if terminal type (or the current value of TERM if no ter-
 minal type is given) has an entry in the hosts termcap(5) or
 terminfo(5)  database. Prints the terminal type to stdout and
 returns 0 if an entry is present otherwise returns 1.
 time [command]
 Executes command (which must be a simple command, not an alias,
 a pipeline, a command list or a parenthesized command list) and
 prints a time summary as described under the time variable. If
 necessary, an extra shell is created to print the time statis-
 tic when the command completes. Without command, prints a time
 summary for the current shell and its children.
 umask [value]
 Sets the file creation mask to value, which is given in octal.
 Common values for the mask are 002, giving all access to the
 group and read and execute access to others, and 022, giving
 read and execute access to the group and others. Without
 value, prints the current file creation mask.
 unalias pattern
 Removes all aliases whose names match pattern. `unalias *'
 thus removes all aliases. It is not an error for nothing to be
 unaliased.
 uncomplete pattern (+)
 Removes all completions whose names match pattern. `uncomplete
 *' thus removes all completions. It is not an error for noth-
 ing to be uncompleted.
 unhash Disables use of the internal hash table to speed location of
 executed programs.
 universe universe (+)
 Sets the universe to universe. (Masscomp/RTU only)
 unlimit [-h] [resource]
 Removes the limitation on resource or, if no resource is speci-
 fied, all resource limitations. With -h, the corresponding
 hard limits are removed. Only the super-user may do this.
 Note that unlimit may not exit successful, since most systems
 do not allow descriptors to be unlimited.
 unset pattern
 Removes all variables whose names match pattern, unless they
 are read-only. `unset *' thus removes all variables unless
 they are read-only; this is a bad idea. It is not an error for
 nothing to be unset.
 unsetenv pattern
 Removes all environment variables whose names match pattern.
 `unsetenv *' thus removes all environment variables; this is a
 bad idea. It is not an error for nothing to be unsetenved.
 ver [systype [command]] (+)
 Without arguments, prints SYSTYPE. With systype, sets SYSTYPE
 to systype. With systype and command, executes command under
 systype. systype may be `bsd4.3' or `sys5.3'. (Domain/OS
 only)
 wait The shell waits for all background jobs. If the shell is
 interactive, an interrupt will disrupt the wait and cause the
 shell to print the names and job numbers of all outstanding
 jobs.
 warp universe (+)
 Sets the universe to universe. (Convex/OS only)
 watchlog (+)
 An alternate name for the log builtin command (q.v.). Avail-
 able only if the shell was so compiled; see the version shell
 variable.
 where command (+)
 Reports all known instances of command, including aliases,
 builtins and executables in path.
 which command (+)
 Displays the command that will be executed by the shell after
 substitutions, path searching, etc. The builtin command is
 just like which(1) , but it correctly reports tcsh aliases and
 builtins and is 10 to 100 times faster. See also the which-
 command editor command.
 while (expr)
 ...
 end Executes the commands between the while and the matching end
 while expr (an expression, as described under Expressions)
 evaluates non-zero. while and end must appear alone on their
 input lines. break and continue may be used to terminate or
 continue the loop prematurely. If the input is a terminal, the
 user is prompted the first time through the loop as with fore-
 ach.
 Special aliases (+)
 If set, each of these aliases executes automatically at the indicated
 time. They are all initially undefined.
 beepcmd Runs when the shell wants to ring the terminal bell.
 cwdcmd Runs after every change of working directory. For example, if
 the user is working on an X window system using xterm(1)  and a
 re-parenting window manager that supports title bars such as
 twm(1)  and does
 > alias cwdcmd 'echo -n "^[]2;${HOST}:$cwd ^G"'
 then the shell will change the title of the running xterm(1)  to
 be the name of the host, a colon, and the full current working
 directory. A fancier way to do that is
 > alias cwdcmd 'echo -n
 "^[]2;${HOST}:$cwd^G^[]1;${HOST}^G"'
 This will put the hostname and working directory on the title
 bar but only the hostname in the icon manager menu.
 Note that putting a cd, pushd or popd in cwdcmd may cause an
 infinite loop. It is the author's opinion that anyone doing so
 will get what they deserve.
 jobcmd Runs before each command gets executed, or when the command
 changes state. This is similar to postcmd, but it does not
 print builtins.
 > alias jobcmd 'echo -n "^[]2\;\!#^G"'
 then executing vi foo.c will put the command string in the
 xterm title bar.
 helpcommand
 Invoked by the run-help editor command. The command name for
 which help is sought is passed as sole argument. For example,
 if one does
 > alias helpcommand '\!:1 --help'
 then the help display of the command itself will be invoked,
 using the GNU help calling convention. Currently there is no
 easy way to account for various calling conventions (e.g., the
 customary Unix `-h'), except by using a table of many commands.
 periodic
 Runs every tperiod minutes. This provides a convenient means
 for checking on common but infrequent changes such as new mail.
 For example, if one does
 > set tperiod = 30
 > alias periodic checknews
 then the checknews(1) program runs every 30 minutes. If peri-
 odic is set but tperiod is unset or set to 0, periodic behaves
 like precmd.
 precmd Runs just before each prompt is printed. For example, if one
 does
 > alias precmd date
 then date(1)  runs just before the shell prompts for each com-
 mand. There are no limits on what precmd can be set to do, but
 discretion should be used.
 postcmd Runs before each command gets executed.
 > alias postcmd 'echo -n "^[]2\;\!#^G"'
 then executing vi foo.c will put the command string in the
 xterm title bar.
 shell Specifies the interpreter for executable scripts which do not
 themselves specify an interpreter. The first word should be a
 full path name to the desired interpreter (e.g., `/bin/csh' or
 `/usr/local/bin/tcsh').
 Special shell variables
 The variables described in this section have special meaning to the
 shell.
 The shell sets addsuffix, argv, autologout, csubstnonl, command,
 echo_style, edit, gid, group, home, loginsh, oid, path, prompt,
 prompt2, prompt3, shell, shlvl, tcsh, term, tty, uid, user and version
 at startup; they do not change thereafter unless changed by the user.
 The shell updates cwd, dirstack, owd and status when necessary, and
 sets logout on logout.
 The shell synchronizes group, home, path, shlvl, term and user with the
 environment variables of the same names: whenever the environment vari-
 able changes the shell changes the corresponding shell variable to
 match (unless the shell variable is read-only) and vice versa. Note
 that although cwd and PWD have identical meanings, they are not syn-
 chronized in this manner, and that the shell automatically intercon-
 verts the different formats of path and PATH.
 addsuffix (+)
 If set, filename completion adds `/' to the end of directories
 and a space to the end of normal files when they are matched
 exactly. Set by default.
 afsuser (+)
 If set, autologout's autolock feature uses its value instead of
 the local username for kerberos authentication.
 ampm (+)
 If set, all times are shown in 12-hour AM/PM format.
 argv The arguments to the shell. Positional parameters are taken
 from argv, i.e., `1ドル' is replaced by `$argv[1]', etc. Set by
 default, but usually empty in interactive shells.
 autocorrect (+)
 If set, the spell-word editor command is invoked automatically
 before each completion attempt.
 autoexpand (+)
 If set, the expand-history editor command is invoked automati-
 cally before each completion attempt.
 autolist (+)
 If set, possibilities are listed after an ambiguous completion.
 If set to `ambiguous', possibilities are listed only when no
 new characters are added by completion.
 autologout (+)
 The first word is the number of minutes of inactivity before
 automatic logout. The optional second word is the number of
 minutes of inactivity before automatic locking. When the shell
 automatically logs out, it prints `auto-logout', sets the vari-
 able logout to `automatic' and exits. When the shell automati-
 cally locks, the user is required to enter his password to con-
 tinue working. Five incorrect attempts result in automatic
 logout. Set to `60' (automatic logout after 60 minutes, and no
 locking) by default in login and superuser shells, but not if
 the shell thinks it is running under a window system (i.e., the
 DISPLAY environment variable is set), the tty is a pseudo-tty
 (pty) or the shell was not so compiled (see the version shell
 variable). See also the afsuser and logout shell variables.
 backslash_quote (+)
 If set, backslashes (`\') always quote `\', `'', and `"'. This
 may make complex quoting tasks easier, but it can cause syntax
 errors in csh(1)  scripts.
 catalog The file name of the message catalog. If set, tcsh use
 `tcsh.${catalog}' as a message catalog instead of default
 `tcsh'.
 cdpath A list of directories in which cd should search for subdirecto-
 ries if they aren't found in the current directory.
 color If set, it enables color display for the builtin ls-F and it
 passes --color=auto to ls. Alternatively, it can be set to
 only ls-F or only ls to enable color to only one command. Set-
 ting it to nothing is equivalent to setting it to (ls-F ls).
 colorcat
 If set, it enables color escape sequence for NLS message files.
 And display colorful NLS messages.
 command (+)
 If set, the command which was passed to the shell with the -c
 flag (q.v.).
 complete (+)
 If set to `enhance', completion 1) ignores case and 2) consid-
 ers periods, hyphens and underscores (`.', `-' and `_') to be
 word separators and hyphens and underscores to be equivalent.
 If set to `igncase', the completion becomes case insensitive.
 continue (+)
 If set to a list of commands, the shell will continue the
 listed commands, instead of starting a new one.
 continue_args (+)
 Same as continue, but the shell will execute:
 echo `pwd` $argv > ~/.<cmd>_pause; %<cmd>
 correct (+)
 If set to `cmd', commands are automatically spelling-corrected.
 If set to `complete', commands are automatically completed. If
 set to `all', the entire command line is corrected.
 csubstnonl (+)
 If set, newlines and carriage returns in command substitution
 are replaced by spaces. Set by default.
 cwd The full pathname of the current directory. See also the
 dirstack and owd shell variables.
 dextract (+)
 If set, `pushd +n' extracts the nth directory from the direc-
 tory stack rather than rotating it to the top.
 dirsfile (+)
 The default location in which `dirs -S' and `dirs -L' look for
 a history file. If unset, ~/.cshdirs is used. Because only
 ~/.tcshrc is normally sourced before ~/.cshdirs, dirsfile
 should be set in ~/.tcshrc rather than ~/.login.
 dirstack (+)
 An array of all the directories on the directory stack.
 `$dirstack[1]' is the current working directory, `$dirstack[2]'
 the first directory on the stack, etc. Note that the current
 working directory is `$dirstack[1]' but `=0' in directory stack
 substitutions, etc. One can change the stack arbitrarily by
 setting dirstack, but the first element (the current working
 directory) is always correct. See also the cwd and owd shell
 variables.
 dspmbyte (+)
 Has an affect iff 'dspm' is listed as part of the version shell
 variable. If set to `euc', it enables display and editing EUC-
 kanji(Japanese) code. If set to `sjis', it enables display and
 editing Shift-JIS(Japanese) code. If set to `big5', it enables
 display and editing Big5(Chinese) code. If set to `utf8', it
 enables display and editing Utf8(Unicode) code. If set to the
 following format, it enables display and editing of original
 multi-byte code format:
 > set dspmbyte = 0000....(256 bytes)....0000
 The table requires just 256 bytes. Each character of 256 char-
 acters corresponds (from left to right) to the ASCII codes
 0x00, 0x01, ... 0xff. Each character is set to number 0,1,2
 and 3. Each number has the following meaning:
 0 ... not used for multi-byte characters.
 1 ... used for the first byte of a multi-byte character.
 2 ... used for the second byte of a multi-byte character.
 3 ... used for both the first byte and second byte of a
 multi-byte character.
 Example:
 If set to `001322', the first character (means 0x00 of the
 ASCII code) and second character (means 0x01 of ASCII code) are
 set to `0'. Then, it is not used for multi-byte characters.
 The 3rd character (0x02) is set to '1', indicating that it is
 used for the first byte of a multi-byte character. The 4th
 character(0x03) is set '3'. It is used for both the first byte
 and the second byte of a multi-byte character. The 5th and 6th
 characters (0x04,0x05) are set to '2', indicating that they are
 used for the second byte of a multi-byte character.
 The GNU fileutils version of ls cannot display multi-byte file-
 names without the -N ( --literal ) option. If you are using
 this version, set the second word of dspmbyte to "ls". If not,
 for example, "ls-F -l" cannot display multi-byte filenames.
 Note:
 This variable can only be used if KANJI and DSPMBYTE has been
 defined at compile time.
 dunique (+)
 If set, pushd removes any instances of name from the stack
 before pushing it onto the stack.
 echo If set, each command with its arguments is echoed just before
 it is executed. For non-builtin commands all expansions occur
 before echoing. Builtin commands are echoed before command and
 filename substitution, because these substitutions are then
 done selectively. Set by the -x command line option.
 echo_style (+)
 The style of the echo builtin. May be set to
 bsd Don't echo a newline if the first argument is `-n'.
 sysv Recognize backslashed escape sequences in echo strings.
 both Recognize both the `-n' flag and backslashed escape
 sequences; the default.
 none Recognize neither.
 Set by default to the local system default. The BSD and System
 V options are described in the echo(1)  man pages on the appro-
 priate systems.
 edit (+)
 If set, the command-line editor is used. Set by default in
 interactive shells.
 ellipsis (+)
 If set, the `%c'/`%.' and `%C' prompt sequences (see the prompt
 shell variable) indicate skipped directories with an ellipsis
 (`...') instead of `/<skipped>'.
 fignore (+)
 Lists file name suffixes to be ignored by completion.
 filec In tcsh, completion is always used and this variable is ignored
 by default. If edit is unset, then the traditional csh comple-
 tion is used. If set in csh, filename completion is used.
 gid (+) The user's real group ID.
 group (+)
 The user's group name.
 highlight
 If set, the incremental search match (in i-search-back and i-
 search-fwd) and the region between the mark and the cursor are
 highlighted in reverse video.
 Highlighting requires more frequent terminal writes, which
 introduces extra overhead. If you care about terminal perfor-
 mance, you may want to leave this unset.
 histchars
 A string value determining the characters used in History sub-
 stitution (q.v.). The first character of its value is used as
 the history substitution character, replacing the default char-
 acter `!'. The second character of its value replaces the
 character `^' in quick substitutions.
 histdup (+)
 Controls handling of duplicate entries in the history list. If
 set to `all' only unique history events are entered in the his-
 tory list. If set to `prev' and the last history event is the
 same as the current command, then the current command is not
 entered in the history. If set to `erase' and the same event
 is found in the history list, that old event gets erased and
 the current one gets inserted. Note that the `prev' and `all'
 options renumber history events so there are no gaps.
 histfile (+)
 The default location in which `history -S' and `history -L'
 look for a history file. If unset, ~/.history is used. hist-
 file is useful when sharing the same home directory between
 different machines, or when saving separate histories on dif-
 ferent terminals. Because only ~/.tcshrc is normally sourced
 before ~/.history, histfile should be set in ~/.tcshrc rather
 than ~/.login.
 histlit (+)
 If set, builtin and editor commands and the savehist mechanism
 use the literal (unexpanded) form of lines in the history list.
 See also the toggle-literal-history editor command.
 history The first word indicates the number of history events to save.
 The optional second word (+) indicates the format in which his-
 tory is printed; if not given, `%h\t%T\t%R\n' is used. The
 format sequences are described below under prompt; note the
 variable meaning of `%R'. Set to `100' by default.
 home Initialized to the home directory of the invoker. The filename
 expansion of `~' refers to this variable.
 ignoreeof
 If set to the empty string or `0' and the input device is a
 terminal, the end-of-file command (usually generated by the
 user by typing `^D' on an empty line) causes the shell to print
 `Use "exit" to leave tcsh.' instead of exiting. This prevents
 the shell from accidentally being killed. Historically this
 setting exited after 26 successive EOF's to avoid infinite
 loops. If set to a number n, the shell ignores n - 1 consecu-
 tive end-of-files and exits on the nth. (+) If unset, `1' is
 used, i.e., the shell exits on a single `^D'.
 implicitcd (+)
 If set, the shell treats a directory name typed as a command as
 though it were a request to change to that directory. If set
 to verbose, the change of directory is echoed to the standard
 output. This behavior is inhibited in non-interactive shell
 scripts, or for command strings with more than one word.
 Changing directory takes precedence over executing a like-named
 command, but it is done after alias substitutions. Tilde and
 variable expansions work as expected.
 inputmode (+)
 If set to `insert' or `overwrite', puts the editor into that
 input mode at the beginning of each line.
 killdup (+)
 Controls handling of duplicate entries in the kill ring. If
 set to `all' only unique strings are entered in the kill ring.
 If set to `prev' and the last killed string is the same as the
 current killed string, then the current string is not entered
 in the ring. If set to `erase' and the same string is found in
 the kill ring, the old string is erased and the current one is
 inserted.
 killring (+)
 Indicates the number of killed strings to keep in memory. Set
 to `30' by default. If unset or set to less than `2', the
 shell will only keep the most recently killed string. Strings
 are put in the killring by the editor commands that delete
 (kill) strings of text, e.g. backward-delete-word, kill-line,
 etc, as well as the copy-region-as-kill command. The yank edi-
 tor command will yank the most recently killed string into the
 command-line, while yank-pop (see Editor commands) can be used
 to yank earlier killed strings.
 listflags (+)
 If set to `x', `a' or `A', or any combination thereof (e.g.,
 `xA'), they are used as flags to ls-F, making it act like `ls
 -xF', `ls -Fa', `ls -FA' or a combination (e.g., `ls -FxA'):
 `a' shows all files (even if they start with a `.'), `A' shows
 all files but `.' and `..', and `x' sorts across instead of
 down. If the second word of listflags is set, it is used as
 the path to `ls(1) '.
 listjobs (+)
 If set, all jobs are listed when a job is suspended. If set to
 `long', the listing is in long format.
 listlinks (+)
 If set, the ls-F builtin command shows the type of file to
 which each symbolic link points.
 listmax (+)
 The maximum number of items which the list-choices editor com-
 mand will list without asking first.
 listmaxrows (+)
 The maximum number of rows of items which the list-choices edi-
 tor command will list without asking first.
 loginsh (+)
 Set by the shell if it is a login shell. Setting or unsetting
 it within a shell has no effect. See also shlvl.
 logout (+)
 Set by the shell to `normal' before a normal logout, `auto-
 matic' before an automatic logout, and `hangup' if the shell
 was killed by a hangup signal (see Signal handling). See also
 the autologout shell variable.
 mail The names of the files or directories to check for incoming
 mail, separated by whitespace, and optionally preceded by a
 numeric word. Before each prompt, if 10 minutes have passed
 since the last check, the shell checks each file and says `You
 have new mail.' (or, if mail contains multiple files, `You have
 new mail in name.') if the filesize is greater than zero in
 size and has a modification time greater than its access time.
 If you are in a login shell, then no mail file is reported
 unless it has been modified after the time the shell has
 started up, to prevent redundant notifications. Most login
 programs will tell you whether or not you have mail when you
 log in.
 If a file specified in mail is a directory, the shell will
 count each file within that directory as a separate message,
 and will report `You have n mails.' or `You have n mails in
 name.' as appropriate. This functionality is provided primar-
 ily for those systems which store mail in this manner, such as
 the Andrew Mail System.
 If the first word of mail is numeric it is taken as a different
 mail checking interval, in seconds.
 Under very rare circumstances, the shell may report `You have
 mail.' instead of `You have new mail.'
 matchbeep (+)
 If set to `never', completion never beeps. If set to
 `nomatch', it beeps only when there is no match. If set to
 `ambiguous', it beeps when there are multiple matches. If set
 to `notunique', it beeps when there is one exact and other
 longer matches. If unset, `ambiguous' is used.
 nobeep (+)
 If set, beeping is completely disabled. See also visiblebell.
 noclobber
 If set, restrictions are placed on output redirection to insure
 that files are not accidentally destroyed and that `>>' redi-
 rections refer to existing files, as described in the
 Input/output section.
 noding If set, disable the printing of `DING!' in the prompt time
 specifiers at the change of hour.
 noglob If set, Filename substitution and Directory stack substitution
 (q.v.) are inhibited. This is most useful in shell scripts
 which do not deal with filenames, or after a list of filenames
 has been obtained and further expansions are not desirable.
 nokanji (+)
 If set and the shell supports Kanji (see the version shell
 variable), it is disabled so that the meta key can be used.
 nonomatch
 If set, a Filename substitution or Directory stack substitution
 (q.v.) which does not match any existing files is left
 untouched rather than causing an error. It is still an error
 for the substitution to be malformed, e.g., `echo [' still
 gives an error.
 nostat (+)
 A list of directories (or glob-patterns which match directo-
 ries; see Filename substitution) that should not be stat(2) ed
 during a completion operation. This is usually used to exclude
 directories which take too much time to stat(2) , for example
 /afs.
 notify If set, the shell announces job completions asynchronously.
 The default is to present job completions just before printing
 a prompt.
 oid (+) The user's real organization ID. (Domain/OS only)
 owd (+) The old working directory, equivalent to the `-' used by cd and
 pushd. See also the cwd and dirstack shell variables.
 padhour If set, enable the printing of padding '0' for hours, in 24 and
 12 hour formats. E.G.: 07:45:42 vs. 7:45:42
 path A list of directories in which to look for executable commands.
 A null word specifies the current directory. If there is no
 path variable then only full path names will execute. path is
 set by the shell at startup from the PATH environment variable
 or, if PATH does not exist, to a system-dependent default some-
 thing like `(/usr/local/bin /usr/bsd /bin /usr/bin .)'. The
 shell may put `.' first or last in path or omit it entirely
 depending on how it was compiled; see the version shell vari-
 able. A shell which is given neither the -c nor the -t option
 hashes the contents of the directories in path after reading
 ~/.tcshrc and each time path is reset. If one adds a new com-
 mand to a directory in path while the shell is active, one may
 need to do a rehash for the shell to find it.
 printexitvalue (+)
 If set and an interactive program exits with a non-zero status,
 the shell prints `Exit status'.
 prompt The string which is printed before reading each command from
 the terminal. prompt may include any of the following format-
 ting sequences (+), which are replaced by the given informa-
 tion:
 %/ The current working directory.
 %~ The current working directory, but with one's home direc-
 tory represented by `~' and other users' home directories
 represented by `~user' as per Filename substitution.
 `~user' substitution happens only if the shell has already
 used `~user' in a pathname in the current session.
 %c[[0]n], %.[[0]n]
 The trailing component of the current working directory, or
 n trailing components if a digit n is given. If n begins
 with `0', the number of skipped components precede the
 trailing component(s) in the format `/<skipped>trailing'.
 If the ellipsis shell variable is set, skipped components
 are represented by an ellipsis so the whole becomes
 `...trailing'. `~' substitution is done as in `%~' above,
 but the `~' component is ignored when counting trailing
 components.
 %C Like %c, but without `~' substitution.
 %h, %!, !
 The current history event number.
 %M The full hostname.
 %m The hostname up to the first `.'.
 %S (%s)
 Start (stop) standout mode.
 %B (%b)
 Start (stop) boldfacing mode.
 %U (%u)
 Start (stop) underline mode.
 %t, %@
 The time of day in 12-hour AM/PM format.
 %T Like `%t', but in 24-hour format (but see the ampm shell
 variable).
 %p The `precise' time of day in 12-hour AM/PM format, with
 seconds.
 %P Like `%p', but in 24-hour format (but see the ampm shell
 variable).
 \c c is parsed as in bindkey.
 ^c c is parsed as in bindkey.
 %% A single `%'.
 %n The user name.
 %j The number of jobs.
 %d The weekday in `Day' format.
 %D The day in `dd' format.
 %w The month in `Mon' format.
 %W The month in `mm' format.
 %y The year in `yy' format.
 %Y The year in `yyyy' format.
 %l The shell's tty.
 %L Clears from the end of the prompt to end of the display or
 the end of the line.
 %$ Expands the shell or environment variable name immediately
 after the `$'.
 %# `>' (or the first character of the promptchars shell vari-
 able) for normal users, `#' (or the second character of
 promptchars) for the superuser.
 %{string%}
 Includes string as a literal escape sequence. It should be
 used only to change terminal attributes and should not move
 the cursor location. This cannot be the last sequence in
 prompt.
 %? The return code of the command executed just before the
 prompt.
 %R In prompt2, the status of the parser. In prompt3, the cor-
 rected string. In history, the history string.
 `%B', `%S', `%U' and `%{string%}' are available in only eight-
 bit-clean shells; see the version shell variable.
 The bold, standout and underline sequences are often used to
 distinguish a superuser shell. For example,
 > set prompt = "%m [%h] %B[%@]%b [%/] you rang? "
 tut [37] [2:54pm] [/usr/accts/sys] you rang? _
 If `%t', `%@', `%T', `%p', or `%P' is used, and noding is not
 set, then print `DING!' on the change of hour (i.e, `:00' min-
 utes) instead of the actual time.
 Set by default to `%# ' in interactive shells.
 prompt2 (+)
 The string with which to prompt in while and foreach loops and
 after lines ending in `\'. The same format sequences may be
 used as in prompt (q.v.); note the variable meaning of `%R'.
 Set by default to `%R? ' in interactive shells.
 prompt3 (+)
 The string with which to prompt when confirming automatic
 spelling correction. The same format sequences may be used as
 in prompt (q.v.); note the variable meaning of `%R'. Set by
 default to `CORRECT>%R (y|n|e|a)? ' in interactive shells.
 promptchars (+)
 If set (to a two-character string), the `%#' formatting
 sequence in the prompt shell variable is replaced with the
 first character for normal users and the second character for
 the superuser.
 pushdtohome (+)
 If set, pushd without arguments does `pushd ~', like cd.
 pushdsilent (+)
 If set, pushd and popd do not print the directory stack.
 recexact (+)
 If set, completion completes on an exact match even if a longer
 match is possible.
 recognize_only_executables (+)
 If set, command listing displays only files in the path that
 are executable. Slow.
 rmstar (+)
 If set, the user is prompted before `rm *' is executed.
 rprompt (+)
 The string to print on the right-hand side of the screen (after
 the command input) when the prompt is being displayed on the
 left. It recognizes the same formatting characters as prompt.
 It will automatically disappear and reappear as necessary, to
 ensure that command input isn't obscured, and will appear only
 if the prompt, command input, and itself will fit together on
 the first line. If edit isn't set, then rprompt will be
 printed after the prompt and before the command input.
 savedirs (+)
 If set, the shell does `dirs -S' before exiting. If the first
 word is set to a number, at most that many directory stack
 entries are saved.
 savehist
 If set, the shell does `history -S' before exiting. If the
 first word is set to a number, at most that many lines are
 saved. (The number must be less than or equal to history.) If
 the second word is set to `merge', the history list is merged
 with the existing history file instead of replacing it (if
 there is one) and sorted by time stamp and the most recent
 events are retained. (+)
 sched (+)
 The format in which the sched builtin command prints scheduled
 events; if not given, `%h\t%T\t%R\n' is used. The format
 sequences are described above under prompt; note the variable
 meaning of `%R'.
 shell The file in which the shell resides. This is used in forking
 shells to interpret files which have execute bits set, but
 which are not executable by the system. (See the description
 of Builtin and non-builtin command execution.) Initialized to
 the (system-dependent) home of the shell.
 shlvl (+)
 The number of nested shells. Reset to 1 in login shells. See
 also loginsh.
 status The status returned by the last command. If it terminated
 abnormally, then 0200 is added to the status. Builtin commands
 which fail return exit status `1', all other builtin commands
 return status `0'.
 symlinks (+)
 Can be set to several different values to control symbolic link
 (`symlink') resolution:
 If set to `chase', whenever the current directory changes to a
 directory containing a symbolic link, it is expanded to the
 real name of the directory to which the link points. This does
 not work for the user's home directory; this is a bug.
 If set to `ignore', the shell tries to construct a current
 directory relative to the current directory before the link was
 crossed. This means that cding through a symbolic link and
 then `cd ..'ing returns one to the original directory. This
 affects only builtin commands and filename completion.
 If set to `expand', the shell tries to fix symbolic links by
 actually expanding arguments which look like path names. This
 affects any command, not just builtins. Unfortunately, this
 does not work for hard-to-recognize filenames, such as those
 embedded in command options. Expansion may be prevented by
 quoting. While this setting is usually the most convenient, it
 is sometimes misleading and sometimes confusing when it fails
 to recognize an argument which should be expanded. A compro-
 mise is to use `ignore' and use the editor command normalize-
 path (bound by default to ^X-n) when necessary.
 Some examples are in order. First, let's set up some play
 directories:
 > cd /tmp
 > mkdir from from/src to
 > ln -s from/src to/dst
 Here's the behavior with symlinks unset,
 > cd /tmp/to/dst; echo $cwd
 /tmp/to/dst
 > cd ..; echo $cwd
 /tmp/from
 here's the behavior with symlinks set to `chase',
 > cd /tmp/to/dst; echo $cwd
 /tmp/from/src
 > cd ..; echo $cwd
 /tmp/from
 here's the behavior with symlinks set to `ignore',
 > cd /tmp/to/dst; echo $cwd
 /tmp/to/dst
 > cd ..; echo $cwd
 /tmp/to
 and here's the behavior with symlinks set to `expand'.
 > cd /tmp/to/dst; echo $cwd
 /tmp/to/dst
 > cd ..; echo $cwd
 /tmp/to
 > cd /tmp/to/dst; echo $cwd
 /tmp/to/dst
 > cd ".."; echo $cwd
 /tmp/from
 > /bin/echo ..
 /tmp/to
 > /bin/echo ".."
 ..
 Note that `expand' expansion 1) works just like `ignore' for
 builtins like cd, 2) is prevented by quoting, and 3) happens
 before filenames are passed to non-builtin commands.
 tcsh (+)
 The version number of the shell in the format `R.VV.PP', where
 `R' is the major release number, `VV' the current version and
 `PP' the patchlevel.
 term The terminal type. Usually set in ~/.login as described under
 Startup and shutdown.
 time If set to a number, then the time builtin (q.v.) executes auto-
 matically after each command which takes more than that many
 CPU seconds. If there is a second word, it is used as a format
 string for the output of the time builtin. (u) The following
 sequences may be used in the format string:
 %U The time the process spent in user mode in cpu seconds.
 %S The time the process spent in kernel mode in cpu seconds.
 %E The elapsed (wall clock) time in seconds.
 %P The CPU percentage computed as (%U + %S) / %E.
 %W Number of times the process was swapped.
 %X The average amount in (shared) text space used in Kbytes.
 %D The average amount in (unshared) data/stack space used in
 Kbytes.
 %K The total space used (%X + %D) in Kbytes.
 %M The maximum memory the process had in use at any time in
 Kbytes.
 %F The number of major page faults (page needed to be brought
 from disk).
 %R The number of minor page faults.
 %I The number of input operations.
 %O The number of output operations.
 %r The number of socket messages received.
 %s The number of socket messages sent.
 %k The number of signals received.
 %w The number of voluntary context switches (waits).
 %c The number of involuntary context switches.
 Only the first four sequences are supported on systems without
 BSD resource limit functions. The default time format is `%Uu
 %Ss %E %P %X+%Dk %I+%Oio %Fpf+%Ww' for systems that support
 resource usage reporting and `%Uu %Ss %E %P' for systems that
 do not.
 Under Sequent's DYNIX/ptx, %X, %D, %K, %r and %s are not avail-
 able, but the following additional sequences are:
 %Y The number of system calls performed.
 %Z The number of pages which are zero-filled on demand.
 %i The number of times a process's resident set size was
 increased by the kernel.
 %d The number of times a process's resident set size was
 decreased by the kernel.
 %l The number of read system calls performed.
 %m The number of write system calls performed.
 %p The number of reads from raw disk devices.
 %q The number of writes to raw disk devices.
 and the default time format is `%Uu %Ss %E %P %I+%Oio
 %Fpf+%Ww'. Note that the CPU percentage can be higher than
 100% on multi-processors.
 tperiod (+)
 The period, in minutes, between executions of the periodic spe-
 cial alias.
 tty (+) The name of the tty, or empty if not attached to one.
 uid (+) The user's real user ID.
 user The user's login name.
 verbose If set, causes the words of each command to be printed, after
 history substitution (if any). Set by the -v command line
 option.
 version (+)
 The version ID stamp. It contains the shell's version number
 (see tcsh), origin, release date, vendor, operating system and
 machine (see VENDOR, OSTYPE and MACHTYPE) and a comma-separated
 list of options which were set at compile time. Options which
 are set by default in the distribution are noted.
 8b The shell is eight bit clean; default
 7b The shell is not eight bit clean
 wide The shell is multibyte encoding clean (like UTF-8)
 nls The system's NLS is used; default for systems with NLS
 lf Login shells execute /etc/csh.login before instead of
 after /etc/csh.cshrc and ~/.login before instead of after
 ~/.tcshrc and ~/.history.
 dl `.' is put last in path for security; default
 nd `.' is omitted from path for security
 vi vi-style editing is the default rather than emacs
 dtr Login shells drop DTR when exiting
 bye bye is a synonym for logout and log is an alternate name
 for watchlog
 al autologout is enabled; default
 kan Kanji is used if appropriate according to locale set-
 tings, unless the nokanji shell variable is set
 sm The system's malloc(3)  is used
 hb The `#!<program> <args>' convention is emulated when exe-
 cuting shell scripts
 ng The newgrp builtin is available
 rh The shell attempts to set the REMOTEHOST environment
 variable
 afs The shell verifies your password with the kerberos server
 if local authentication fails. The afsuser shell vari-
 able or the AFSUSER environment variable override your
 local username if set.
 An administrator may enter additional strings to indicate dif-
 ferences in the local version.
 visiblebell (+)
 If set, a screen flash is used rather than the audible bell.
 See also nobeep.
 watch (+)
 A list of user/terminal pairs to watch for logins and logouts.
 If either the user is `any' all terminals are watched for the
 given user and vice versa. Setting watch to `(any any)'
 watches all users and terminals. For example,
 set watch = (george ttyd1 any console $user any)
 reports activity of the user `george' on ttyd1, any user on the
 console, and oneself (or a trespasser) on any terminal.
 Logins and logouts are checked every 10 minutes by default, but
 the first word of watch can be set to a number to check every
 so many minutes. For example,
 set watch = (1 any any)
 reports any login/logout once every minute. For the impatient,
 the log builtin command triggers a watch report at any time.
 All current logins are reported (as with the log builtin) when
 watch is first set.
 The who shell variable controls the format of watch reports.
 who (+) The format string for watch messages. The following sequences
 are replaced by the given information:
 %n The name of the user who logged in/out.
 %a The observed action, i.e., `logged on', `logged off' or
 `replaced olduser on'.
 %l The terminal (tty) on which the user logged in/out.
 %M The full hostname of the remote host, or `local' if the
 login/logout was from the local host.
 %m The hostname of the remote host up to the first `.'. The
 full name is printed if it is an IP address or an X Window
 System display.
 %M and %m are available on only systems that store the remote
 hostname in /etc/utmp. If unset, `%n has %a %l from %m.' is
 used, or `%n has %a %l.' on systems which don't store the
 remote hostname.
 wordchars (+)
 A list of non-alphanumeric characters to be considered part of
 a word by the forward-word, backward-word etc., editor com-
 mands. If unset, `*?_-.[]~=' is used.

ENVIRONMENT

 AFSUSER (+)
 Equivalent to the afsuser shell variable.
 COLUMNS The number of columns in the terminal. See Terminal manage-
 ment.
 DISPLAY Used by X Window System (see X(1)). If set, the shell does not
 set autologout (q.v.).
 EDITOR The pathname to a default editor. See also the VISUAL environ-
 ment variable and the run-fg-editor editor command.
 GROUP (+)
 Equivalent to the group shell variable.
 HOME Equivalent to the home shell variable.
 HOST (+)
 Initialized to the name of the machine on which the shell is
 running, as determined by the gethostname(2) system call.
 HOSTTYPE (+)
 Initialized to the type of machine on which the shell is run-
 ning, as determined at compile time. This variable is obsolete
 and will be removed in a future version.
 HPATH (+)
 A colon-separated list of directories in which the run-help
 editor command looks for command documentation.
 LANG Gives the preferred character environment. See Native Language
 System support.
 LC_CTYPE
 If set, only ctype character handling is changed. See Native
 Language System support.
 LINES The number of lines in the terminal. See Terminal management.
 LS_COLORS
 The format of this variable is reminiscent of the termcap(5)
 file format; a colon-separated list of expressions of the form
 "xx=string", where "xx" is a two-character variable name. The
 variables with their associated defaults are:
 no 0 Normal (non-filename) text
 fi 0 Regular file
 di 01;34 Directory
 ln 01;36 Symbolic link
 pi 33 Named pipe (FIFO)
 so 01;35 Socket
 do 01;35 Door
 bd 01;33 Block device
 cd 01;32 Character device
 ex 01;32 Executable file
 mi (none) Missing file (defaults to fi)
 or (none) Orphaned symbolic link (defaults to ln)
 lc ^[[ Left code
 rc m Right code
 ec (none) End code (replaces lc+no+rc)
 You need to include only the variables you want to change from
 the default.
 File names can also be colorized based on filename extension.
 This is specified in the LS_COLORS variable using the syntax
 "*ext=string". For example, using ISO 6429 codes, to color all
 C-language source files blue you would specify "*.c=34". This
 would color all files ending in .c in blue (34) color.
 Control characters can be written either in C-style-escaped
 notation, or in stty-like ^-notation. The C-style notation
 adds ^[ for Escape, _ for a normal space character, and ? for
 Delete. In addition, the ^[ escape character can be used to
 override the default interpretation of ^[, ^, : and =.
 Each file will be written as <lc> <color-code> <rc> <filename>
 <ec>. If the <ec> code is undefined, the sequence <lc> <no>
 <rc> will be used instead. This is generally more convenient
 to use, but less general. The left, right and end codes are
 provided so you don't have to type common parts over and over
 again and to support weird terminals; you will generally not
 need to change them at all unless your terminal does not use
 ISO 6429 color sequences but a different system.
 If your terminal does use ISO 6429 color codes, you can compose
 the type codes (i.e., all except the lc, rc, and ec codes) from
 numerical commands separated by semicolons. The most common
 commands are:
 0 to restore default color
 1 for brighter colors
 4 for underlined text
 5 for flashing text
 30 for black foreground
 31 for red foreground
 32 for green foreground
 33 for yellow (or brown) foreground
 34 for blue foreground
 35 for purple foreground
 36 for cyan foreground
 37 for white (or gray) foreground
 40 for black background
 41 for red background
 42 for green background
 43 for yellow (or brown) background
 44 for blue background
 45 for purple background
 46 for cyan background
 47 for white (or gray) background
 Not all commands will work on all systems or display devices.
 A few terminal programs do not recognize the default end code
 properly. If all text gets colorized after you do a directory
 listing, try changing the no and fi codes from 0 to the numeri-
 cal codes for your standard fore- and background colors.
 MACHTYPE (+)
 The machine type (microprocessor class or machine model), as
 determined at compile time.
 NOREBIND (+)
 If set, printable characters are not rebound to self-insert-
 command. See Native Language System support.
 OSTYPE (+)
 The operating system, as determined at compile time.
 PATH A colon-separated list of directories in which to look for exe-
 cutables. Equivalent to the path shell variable, but in a dif-
 ferent format.
 PWD (+) Equivalent to the cwd shell variable, but not synchronized to
 it; updated only after an actual directory change.
 REMOTEHOST (+)
 The host from which the user has logged in remotely, if this is
 the case and the shell is able to determine it. Set only if
 the shell was so compiled; see the version shell variable.
 SHLVL (+)
 Equivalent to the shlvl shell variable.
 SYSTYPE (+)
 The current system type. (Domain/OS only)
 TERM Equivalent to the term shell variable.
 TERMCAP The terminal capability string. See Terminal management.
 USER Equivalent to the user shell variable.
 VENDOR (+)
 The vendor, as determined at compile time.
 VISUAL The pathname to a default full-screen editor. See also the
 EDITOR environment variable and the run-fg-editor editor com-
 mand.

FILES

 /etc/csh.cshrc Read first by every shell. ConvexOS, Stellix and Intel
 use /etc/cshrc and NeXTs use /etc/cshrc.std. A/UX,
 AMIX, Cray and IRIX have no equivalent in csh(1) , but
 read this file in tcsh anyway. Solaris 2.x does not
 have it either, but tcsh reads /etc/.cshrc. (+)
 /etc/csh.login Read by login shells after /etc/csh.cshrc. ConvexOS,
 Stellix and Intel use /etc/login, NeXTs use
 /etc/login.std, Solaris 2.x uses /etc/.login and A/UX,
 AMIX, Cray and IRIX use /etc/cshrc.
 ~/.tcshrc (+) Read by every shell after /etc/csh.cshrc or its equiva-
 lent.
 ~/.cshrc Read by every shell, if ~/.tcshrc doesn't exist, after
 /etc/csh.cshrc or its equivalent. This manual uses
 `~/.tcshrc' to mean `~/.tcshrc or, if ~/.tcshrc is not
 found, ~/.cshrc'.
 ~/.history Read by login shells after ~/.tcshrc if savehist is
 set, but see also histfile.
 ~/.login Read by login shells after ~/.tcshrc or ~/.history.
 The shell may be compiled to read ~/.login before
 instead of after ~/.tcshrc and ~/.history; see the ver-
 sion shell variable.
 ~/.cshdirs (+) Read by login shells after ~/.login if savedirs is set,
 but see also dirsfile.
 /etc/csh.logout Read by login shells at logout. ConvexOS, Stellix and
 Intel use /etc/logout and NeXTs use /etc/logout.std.
 A/UX, AMIX, Cray and IRIX have no equivalent in csh(1) ,
 but read this file in tcsh anyway. Solaris 2.x does
 not have it either, but tcsh reads /etc/.logout. (+)
 ~/.logout Read by login shells at logout after /etc/csh.logout or
 its equivalent.
 /bin/sh Used to interpret shell scripts not starting with a
 `#'.
 /tmp/sh* Temporary file for `<<'.
 /etc/passwd Source of home directories for `~name' substitutions.
 The order in which startup files are read may differ if the shell was
 so compiled; see Startup and shutdown and the version shell variable.

NEW FEATURES (+)

 This manual describes tcsh as a single entity, but experienced csh(1) 
 users will want to pay special attention to tcsh's new features.
 A command-line editor, which supports GNU Emacs or vi(1) -style key
 bindings. See The command-line editor and Editor commands.
 Programmable, interactive word completion and listing. See Completion
 and listing and the complete and uncomplete builtin commands.
 Spelling correction (q.v.) of filenames, commands and variables.
 Editor commands (q.v.) which perform other useful functions in the mid-
 dle of typed commands, including documentation lookup (run-help), quick
 editor restarting (run-fg-editor) and command resolution (which-com-
 mand).
 An enhanced history mechanism. Events in the history list are time-
 stamped. See also the history command and its associated shell vari-
 ables, the previously undocumented `#' event specifier and new modi-
 fiers under History substitution, the *-history, history-search-*, i-
 search-*, vi-search-* and toggle-literal-history editor commands and
 the histlit shell variable.
 Enhanced directory parsing and directory stack handling. See the cd,
 pushd, popd and dirs commands and their associated shell variables, the
 description of Directory stack substitution, the dirstack, owd and sym-
 links shell variables and the normalize-command and normalize-path edi-
 tor commands.
 Negation in glob-patterns. See Filename substitution.
 New File inquiry operators (q.v.) and a filetest builtin which uses
 them.
 A variety of Automatic, periodic and timed events (q.v.) including
 scheduled events, special aliases, automatic logout and terminal lock-
 ing, command timing and watching for logins and logouts.
 Support for the Native Language System (see Native Language System sup-
 port), OS variant features (see OS variant support and the echo_style
 shell variable) and system-dependent file locations (see FILES).
 Extensive terminal-management capabilities. See Terminal management.
 New builtin commands including builtins, hup, ls-F, newgrp, printenv,
 which and where (q.v.).
 New variables that make useful information easily available to the
 shell. See the gid, loginsh, oid, shlvl, tcsh, tty, uid and version
 shell variables and the HOST, REMOTEHOST, VENDOR, OSTYPE and MACHTYPE
 environment variables.
 A new syntax for including useful information in the prompt string (see
 prompt). and special prompts for loops and spelling correction (see
 prompt2 and prompt3).
 Read-only variables. See Variable substitution.

BUGS

 When a suspended command is restarted, the shell prints the directory
 it started in if this is different from the current directory. This
 can be misleading (i.e., wrong) as the job may have changed directories
 internally.
 Shell builtin functions are not stoppable/restartable. Command
 sequences of the form `a ; b ; c' are also not handled gracefully when
 stopping is attempted. If you suspend `b', the shell will then immedi-
 ately execute `c'. This is especially noticeable if this expansion
 results from an alias. It suffices to place the sequence of commands
 in ()'s to force it to a subshell, i.e., `( a ; b ; c )'.
 Control over tty output after processes are started is primitive; per-
 haps this will inspire someone to work on a good virtual terminal
 interface. In a virtual terminal interface much more interesting
 things could be done with output control.
 Alias substitution is most often used to clumsily simulate shell proce-
 dures; shell procedures should be provided rather than aliases.
 Commands within loops are not placed in the history list. Control
 structures should be parsed rather than being recognized as built-in
 commands. This would allow control commands to be placed anywhere, to
 be combined with `|', and to be used with `&' and `;' metasyntax.
 foreach doesn't ignore here documents when looking for its end.
 It should be possible to use the `:' modifiers on the output of command
 substitutions.
 The screen update for lines longer than the screen width is very poor
 if the terminal cannot move the cursor up (i.e., terminal type `dumb').
 HPATH and NOREBIND don't need to be environment variables.
 Glob-patterns which do not use `?', `*' or `[]' or which use `{}' or
 `~' are not negated correctly.
 The single-command form of if does output redirection even if the
 expression is false and the command is not executed.
 ls-F includes file identification characters when sorting filenames and
 does not handle control characters in filenames well. It cannot be
 interrupted.
 Command substitution supports multiple commands and conditions, but not
 cycles or backward gotos.
 Report bugs at http://bugs.gw.com/, preferably with fixes. If you want
 to help maintain and test tcsh, send mail to tcsh-request@mx.gw.com
 with the text `subscribe tcsh' on a line by itself in the body.

THE T IN TCSH

 In 1964, DEC produced the PDP-6. The PDP-10 was a later re-implementa-
 tion. It was re-christened the DECsystem-10 in 1970 or so when DEC
 brought out the second model, the KI10.
 TENEX was created at Bolt, Beranek & Newman (a Cambridge, Massachusetts
 think tank) in 1972 as an experiment in demand-paged virtual memory
 operating systems. They built a new pager for the DEC PDP-10 and cre-
 ated the OS to go with it. It was extremely successful in academia.
 In 1975, DEC brought out a new model of the PDP-10, the KL10; they
 intended to have only a version of TENEX, which they had licensed from
 BBN, for the new box. They called their version TOPS-20 (their capi-
 talization is trademarked). A lot of TOPS-10 users (`The OPerating
 System for PDP-10') objected; thus DEC found themselves supporting two
 incompatible systems on the same hardware--but then there were 6 on the
 PDP-11!
 TENEX, and TOPS-20 to version 3, had command completion via a user-
 code-level subroutine library called ULTCMD. With version 3, DEC moved
 all that capability and more into the monitor (`kernel' for you Unix
 types), accessed by the COMND% JSYS (`Jump to SYStem' instruction, the
 supervisor call mechanism [are my IBM roots also showing?]).
 The creator of tcsh was impressed by this feature and several others of
 TENEX and TOPS-20, and created a version of csh which mimicked them.

LIMITATIONS

 Words can be no longer than 1024 characters.
 The system limits argument lists to 10240 characters.
 The number of arguments to a command which involves filename expansion
 is limited to 1/6th the number of characters allowed in an argument
 list.
 Command substitutions may substitute no more characters than are
 allowed in an argument list.
 To detect looping, the shell restricts the number of alias substitu-
 tions on a single line to 20.

SEE ALSO

 csh(1) , emacs(1) , ls(1) , newgrp(1) , sh(1) , setpath(1), stty(1) , su(1) ,
 tset(1) , vi(1) , x(1), access(2) , execve(2) , fork(2) , killpg(2) ,
 pipe(2) , setrlimit(2) , sigvec(2) , stat(2) , umask(2) , vfork(2) , wait(2) ,
 malloc(3) , setlocale(3) , tty(4) , a.out(5) , termcap(5), environ(7) ,
 termio(7), Introduction to the C Shell

VERSION

 This manual documents tcsh 6.15.00 (Astron) 2007年03月03日.

AUTHORS

 William Joy
 Original author of csh(1) 
 J.E. Kulp, IIASA, Laxenburg, Austria
 Job control and directory stack features
 Ken Greer, HP Labs, 1981
 File name completion
 Mike Ellis, Fairchild, 1983
 Command name recognition/completion
 Paul Placeway, Ohio State CIS Dept., 1983-1993
 Command line editor, prompt routines, new glob syntax and numerous
 fixes and speedups
 Karl Kleinpaste, CCI 1983-4
 Special aliases, directory stack extraction stuff, login/logout
 watch, scheduled events, and the idea of the new prompt format
 Rayan Zachariassen, University of Toronto, 1984
 ls-F and which builtins and numerous bug fixes, modifications and
 speedups
 Chris Kingsley, Caltech
 Fast storage allocator routines
 Chris Grevstad, TRW, 1987
 Incorporated 4.3BSD csh into tcsh
 Christos S. Zoulas, Cornell U. EE Dept., 1987-94
 Ports to HPUX, SVR2 and SVR3, a SysV version of getwd.c,
 SHORT_STRINGS support and a new version of sh.glob.c
 James J Dempsey, BBN, and Paul Placeway, OSU, 1988
 A/UX port
 Daniel Long, NNSC, 1988
 wordchars
 Patrick Wolfe, Kuck and Associates, Inc., 1988
 vi mode cleanup
 David C Lawrence, Rensselaer Polytechnic Institute, 1989
 autolist and ambiguous completion listing
 Alec Wolman, DEC, 1989
 Newlines in the prompt
 Matt Landau, BBN, 1989
 ~/.tcshrc
 Ray Moody, Purdue Physics, 1989
 Magic space bar history expansion
 Mordechai ????, Intel, 1989
 printprompt() fixes and additions
 Kazuhiro Honda, Dept. of Computer Science, Keio University, 1989
 Automatic spelling correction and prompt3
 Per Hedeland, Ellemtel, Sweden, 1990-
 Various bugfixes, improvements and manual updates
 Hans J. Albertsson (Sun Sweden)
 ampm, settc and telltc
 Michael Bloom
 Interrupt handling fixes
 Michael Fine, Digital Equipment Corp
 Extended key support
 Eric Schnoebelen, Convex, 1990
 Convex support, lots of csh bug fixes, save and restore of directory
 stack
 Ron Flax, Apple, 1990
 A/UX 2.0 (re)port
 Dan Oscarsson, LTH Sweden, 1990
 NLS support and simulated NLS support for non NLS sites, fixes
 Johan Widen, SICS Sweden, 1990
 shlvl, Mach support, correct-line, 8-bit printing
 Matt Day, Sanyo Icon, 1990
 POSIX termio support, SysV limit fixes
 Jaap Vermeulen, Sequent, 1990-91
 Vi mode fixes, expand-line, window change fixes, Symmetry port
 Martin Boyer, Institut de recherche d'Hydro-Quebec, 1991
 autolist beeping options, modified the history search to search for
 the whole string from the beginning of the line to the cursor.
 Scott Krotz, Motorola, 1991
 Minix port
 David Dawes, Sydney U. Australia, Physics Dept., 1991
 SVR4 job control fixes
 Jose Sousa, Interactive Systems Corp., 1991
 Extended vi fixes and vi delete command
 Marc Horowitz, MIT, 1991
 ANSIfication fixes, new exec hashing code, imake fixes, where
 Bruce Sterling Woodcock, sterling@netcom.com, 1991-1995
 ETA and Pyramid port, Makefile and lint fixes, ignoreeof=n addition,
 and various other portability changes and bug fixes
 Jeff Fink, 1992
 complete-word-fwd and complete-word-back
 Harry C. Pulley, 1992
 Coherent port
 Andy Phillips, Mullard Space Science Lab U.K., 1992
 VMS-POSIX port
 Beto Appleton, IBM Corp., 1992
 Walking process group fixes, csh bug fixes, POSIX file tests, POSIX
 SIGHUP
 Scott Bolte, Cray Computer Corp., 1992
 CSOS port
 Kaveh R. Ghazi, Rutgers University, 1992
 Tek, m88k, Titan and Masscomp ports and fixes. Added autoconf sup-
 port.
 Mark Linderman, Cornell University, 1992
 OS/2 port
 Mika Liljeberg, liljeber@kruuna.Helsinki.FI, 1992
 Linux port
 Tim P. Starrin, NASA Langley Research Center Operations, 1993
 Read-only variables
 Dave Schweisguth, Yale University, 1993-4
 New man page and tcsh.man2html
 Larry Schwimmer, Stanford University, 1993
 AFS and HESIOD patches
 Luke Mewburn, RMIT University, 1994-6
 Enhanced directory printing in prompt, added ellipsis and rprompt.
 Edward Hutchins, Silicon Graphics Inc., 1996
 Added implicit cd.
 Martin Kraemer, 1997
 Ported to Siemens Nixdorf EBCDIC machine
 Amol Deshpande, Microsoft, 1997
 Ported to WIN32 (Windows/95 and Windows/NT); wrote all the missing
 library and message catalog code to interface to Windows.
 Taga Nayuta, 1998
 Color ls additions.

THANKS TO

 Bryan Dunlap, Clayton Elwell, Karl Kleinpaste, Bob Manson, Steve Romig,
 Diana Smetters, Bob Sutterfield, Mark Verber, Elizabeth Zwicky and all
 the other people at Ohio State for suggestions and encouragement
 All the people on the net, for putting up with, reporting bugs in, and
 suggesting new additions to each and every version
 Richard M. Alderson III, for writing the `T in tcsh' section
Astron 6.15.00 3 March 2007 tcsh(1)