<TITLE>sysconf</TITLE> <body bgcolor="#ffffcc"> <hr> <pre> <h3>SYSCONF(3) Linux Programmer's Manual SYSCONF(3) </h3> <h3>NAME </h3> sysconf - Get configuration information at runtime <h3>SYNOPSIS </h3> #include <unistd.h> long sysconf(int name); <h3>DESCRIPTION </h3> sysconf() provides a way for the application to determine values for system limits or options at runtime. The equivalent macros defined in <unistd.h> can only give conservative values; if an application wants to take advantage of values which may change, a call to sysconf() can be made, which may yield more liberal results. For getting information about a particular file, see fpathconf() or pathconf(). The following values are supported for name. First, the POSIX.1 compatible values: _SC_ARG_MAX The maximum length of the arguments to the exec() family of functions; the corresponding macro is ARG_MAX. _SC_CHILD_MAX The number of simultaneous processes per user id, the corresponding macro is _POSIX_CHILD_MAX. _SC_CLK_TCK The number of clock ticks per second; the corre- sponding macro is CLK_TCK. _SC_STREAM_MAX The maximum number of streams that a process can have open at any time. The corresponding POSIX macro is STREAM_MAX, the corresponding standard C macro is FOPEN_MAX. _SC_TZNAME_MAX The maximum number of bytes in a timezone name, the corresponding macro is TZNAME_MAX. _SC_OPEN_MAX The maximum number of files that a process can have open at any time, the corresponding macro is _POSIX_OPEN_MAX. _SC_JOB_CONTROL This indicates whether POSIX - style job control is supported, the corresponding macro is <h3>GNU April 18, 1993 1 </h3> <h3>SYSCONF(3) Linux Programmer's Manual SYSCONF(3) </h3> _POSIX_JOB_CONTROL. _SC_SAVED_IDS This indicates whether a process has a saved set- user-ID and a saved set-group-ID; the corresponding macro is _POSIX_SAVED_IDS. _SC_VERSION indicates the year and month the POSIX.1 standard was approved in the format YYYYMML;the value 199009L indicates the most recent revision, 1990. Next, the POSIX.2 values: _SC_BC_BASE_MAX indicates the maximum obase value accepted by the bc(1) utility; the corresponding macro is BC_BASE_MAX. _SC_BC_DIM_MAX indicates the maximum value of elements permitted in an array by bc(1); the corresponding macro is BC_DIM_MAX. _SC_BC_SCALE_MAX indicates the maximum scale value allowed by bc(1); the corresponding macro is BC_SCALE_MAX. _SC_BC_STRING_MAX indicates the maximum length of a string accepted by bc(1); the corresponding macro is BC_STRING_MAX. _SC_COLL_WEIGHTS_MAX indicates the maximum numbers of weights that can be assigned to an entry of the LC_COLLATE order keyword in the locale definition file; the corre- sponding macro is COLL_WEIGHTS_MAX. _SC_EXPR_NEST_MAX is the maximum number of expressions which can be nested within parentheses by expr(1). The corre- sponding macro is EXPR_NEST_MAX. _SC_LINE_MAX The maximum length of a utility's input line length, either from standard input or from a file. This includes length for a trailing newline. The corresponding macro is LINE_MAX. _SC_RE_DUP_MAX The maximum number of repeated occurrences of a regular expression when the interval notation \{m,n\} is used. The value of the corresponding macro is RE_DUP_MAX. <h3>GNU April 18, 1993 2 </h3> <h3>SYSCONF(3) Linux Programmer's Manual SYSCONF(3) </h3> _SC_2_VERSION indicates the version of the POSIX.2 standard in the format of YYYYMML. The corresponding macro is POSIX2_VERSION. _SC_2_DEV indicates whether the POSIX.2 C language develop- ment facilities are supported. The corresponding macro is POSIX2_C_DEV. _SC_2_FORT_DEV indicates whether the POSIX.2 FORTRAN development utilities are supported. The corresponding macro is POSIX2_FORT_RUN. _SC_2_FORT_RUN indicates whether the POSIX.2 FORTRAN runtime util- ities are supported. The corresponding macro is POSIX2_FORT_RUN. POSIX2_LOCALEDEF indicates whether the POSIX.2 creation of locates via locale(1) is supported. The corresponding macro is POSIX2_LOCALEDEF. _SC_2_SW_DEV indicates whether the POSIX.2 software development utilities option is supported. The corresponding macro is POSIX2_SW_DEV. <h3>RETURN VALUE </h3> The value returned is the value of the system resource, 1 if a queried option is available, 0 if it is not, or -1 on error. The variable errno is not set. <h3>CONFORMS TO </h3> POSIX.1, proposed POSIX.2 <h3>BUGS </h3> It is difficult use ARG_MAX because it is not specified how much of the argument space for exec() is consumed by the user's environment variables. Some returned values may be huge; they are not suitable for allocating memory. POSIX.2 is not yet an approved standard; the information in this manpage is subject to change. </pre> <hr> <h3>SEE ALSO </h3><p> <a href=bc.htm>bc</a>, <a href=expr.htm>expr</a>, <a href=locale.htm>locale</a>, <a href=fpathconf.htm>fpathconf</a>, <a href=pathconf.htm>pathconf</a>, <pre> <h3>GNU April 18, 1993 3 </h3> </pre> <P> <hr> <p> <center> <table border=2 width=80%> <tr align=center> <td width=25%> <a href=../index.htm>Top</a> </td><td width=25%> <a href=../master_index.html>Master Index</a> </td><td width=25%> <a href=../SYNTAX/keywords.html>Keywords</a> </td><td width=25%> <a href=../FUNCTIONS/index.htm>Functions</a> </td> </tr> </table> </center> <p> <hr> This manual page was brought to you by <i>mjl_man V-2.0</i>
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