shopt

Shell Options

Syntax
 shopt [-pqsu] [-o] [optname ...]
Options
 -s Enable (set) each optname
 -u Disable (unset) each optname.
 -p Display a list of all settable options, with an indication of 
 whether or not each is set. The output is displayed in a form 
 that can be reused as input. (-p is the default action)
 -q Suppresses normal output; the return status indicates whether the optname
 is set or unset. If multiple optname arguments are given with '-q',
 the return status is zero if all optnames are enabled; non-zero otherwise. 
 -o Restricts the values of optname to be those defined for the '-o' option to 
 the set builtin.

If either '-s' or '-u' is used with no optname arguments, the display is limited to those options which are set or unset, respectively.
Unless otherwise noted, the shopt options are disabled (off) by default.
The return status is zero unless an optname was *not* enabled or was not a valid shell option.

optnames:
cdable_vars
 If this is set, an argument to the cd builtin command that 
 is not a directory is assumed to be the name of a variable whose value is 
 the directory to change to. 
cdspell
 If set, minor errors in the spelling of a directory component in a cd 
 command will be corrected. The errors checked for are transposed characters, 
 a missing character, and a character too many. If a correction is found, the 
 corrected path is printed, and the command proceeds. This option is only used 
 by interactive shells.
checkhash
 If this is set, Bash checks that a command found in the hash table exists 
 before trying to execute it. If a hashed command no longer exists, a normal 
 path search is performed. 
checkwinsize
 If set, Bash checks the window size after each command and, if necessary, 
 updates the values of LINES and COLUMNS. 
cmdhist
 If set, Bash attempts to save all lines of a multiple-line command in the 
 same history entry. This allows easy re-editing of multi-line commands. 
dotglob
 If set, Bash includes filenames beginning with a '.' in the results of filename 
 expansion. 
execfail
 If this is set, a non-interactive shell will not exit if it cannot execute 
 the file specified as an argument to the exec builtin command. 
 An interactive shell does not exit if exec fails. 
expand_aliases
 If set, aliases are expanded.
 This option is enabled by default for interactive shells. 
extglob
 If set, the extended pattern matching features described above are enabled. 
histappend
 If set, the history list is appended to the history file when the shell exits,
 rather than overwriting the history file. 
 shopt -s histappend
 To append every line to history individually set:
 PROMPT_COMMAND='history -a'
 With these two settings, a new shell will get the history lines from all previous
 shells instead of the default 'last window closed'>history
 (the history file is named by the value of the HISTFILE variable)
histreedit
 If set, and Readline is being used, a user is given the opportunity to re-edit 
 a failed history substitution. 
histverify
 If set, and Readline is being used, the results of history substitution 
 are not immediately passed to the shell parser. Instead, the resulting line 
 is loaded into the Readline editing buffer, allowing further modification. 
hostcomplete
 If set, and Readline is being used, Bash will attempt to perform hostname 
 completion when a word containing a '@' is being completed. 
 This option is enabled by default. 
huponexit
 If set, Bash will send SIGHUP  to all jobs when an interactive login shell exits. 
interactive_comments
 Allow a word beginning with '#' to cause that word and all 
 remaining characters on that line to be ignored in an interactive shell.
 This option is enabled by default. 
lithist
 If enabled, and the cmdhist option is enabled, multi-line commands 
 are saved to the history with embedded newlines rather than using semicolon 
 separators where possible. 
mailwarn
 If set, and a file that Bash is checking for mail has been accessed since the
 last time it was checked, the message "The mail in mailfile has been read" is displayed.
no_empty_cmd_completion
 If set, and Readline is being used, Bash will not attempt to search the 
 PATH for possible completions when completion is attempted on 
 an empty line. 
nocaseglob
 If set, Bash matches filenames in a case-insensitive fashion when performing 
 filename expansion. 
nullglob
 If set, Bash allows filename patterns which match no files to expand to 
 a null string, rather than themselves. 
progcomp
 If set, the programmable completion facilities are enabled.
 This option is enabled by default. 
promptvars
 If set, prompt strings undergo variable and parameter expansion after being 
 expanded. This option is enabled by default. 
restricted_shell
 The shell sets this option if it is started in restricted mode. The value 
 can not be changed. This is not reset when the startup files are executed, 
 allowing the startup files to discover whether or not a shell is restricted. 
shift_verbose
 If this is set, the shift builtin prints an error message when 
 the shift count exceeds the number of positional parameters. 
sourcepath
 If set, the source builtin uses the value of PATH to find the directory containing
 the file supplied as an argument. This option is enabled by default.
xpg_echo
 If set, the echo builtin expands backslash-escape sequences 
 by default.

'shopt' is a BASH builtin command.

Examples

Turn on spell checker for directory names in the cd builtin:

$ shopt -s cdspell

"The dogma of the ghost in the machine" ~ Gilbert Ryle

Related Linux commands

env - Display, set, or remove environment variables.
function - Define Function Macros.
local - Create variables.
logname - Print current login name.
set - Manipulate shell variables and functions.
uname - Print system information.
users - Print login names of users currently logged in.
who - Print who is currently logged in.
Equivalent Windows commands: SETLOCAL - Set options to control the visibility of variables.