SYSCONF(3)               BSD Library Functions Manual               SYSCONF(3)

NAME
     sysconf -- get configurable system variables

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     ##include <>

     long
     sysconf(int name);

DESCRIPTION
     This interface is defined by IE Std 1003.1-1988 (``POSIX.1'').  A far
     more complete interface is available using sysctl(3).

     The sysconf() function provides a method for applications to determine
     the current value of a configurable system limit or option variable.  The
     name argument specifies the system variable to be queried.  Symbolic con-
     stants for each name value are found in the include file .
     Shell programmers who need access to these parameters should use the
     getconf(1) utility.

     The available values are as follows:

     SCARGMAX
             The maximum bytes of argument to execve(2).

     SCHILDMAX
             The maximum number of simultaneous processes per user id.

     SCLKTCK
             The frequency of the statistics clock in ticks per second.

     SCIOVMAX
             The maximum number of elements in the I/O vector used by
             readv(2), writev(2), recvmsg(2), and sendmsg(2).

     SCNGROUPSMAX
             The maximum number of supplemental groups.

     SCNPROCESORSCONF
             The number of processors configured.

     SCNPROCESORSONLN
             The number of processors currently online.

     SCOPENMAX
             The maximum number of open files per user id.

     SCSTREAMAX
             The minimum maximum number of streams that a process may have
             open at any one time.

     SCTZNAMEMAX
             The minimum maximum number of types supported for the name of a
             timezone.

     SCJOBCONTROL
             Return 1 if job control is available on this system, otherwise
             -1.

     SCSAVEDIDS
             Returns 1 if saved set-group and saved set-user ID is available,
             otherwise -1.

     SCVERSION
             The version of IE Std 1003.1 (``POSIX.1'') with which the sys-
             tem attempts to comply.

     SCBCBASEMAX
             The maximum ibase/obase values in the bc(1) utility.

     SCBCDIMAX
             The maximum array size in the bc(1) utility.

     SCBCSCALEMAX
             The maximum scale value in the bc(1) utility.

     SCBCSTRINGMAX
             The maximum string length in the bc(1) utility.

     SCOLWEIGHTSMAX
             The maximum number of weights that can be assigned to any entry
             of the LCOLATE order keyword in the locale definition file.

     SCEXPRNESTMAX
             The maximum number of expressions that can be nested within
             parenthesis by the expr(1) utility.

     SCLINEMAX
             The maximum length in bytes of a text-processing utility's input
             line.

     SCREDUPMAX
             The maximum number of repeated occurrences of a regular expres-
             sion permitted when using interval notation.

     SC2VERSION
             The version of IE Std 1003.2 (``POSIX.2'') with which the sys-
             tem attempts to comply.

     SC2CBIND
             Return 1 if the system's C-language development facilities sup-
             port the C-Language Bindings Option, otherwise -1.

     SC2CDEV
             Return 1 if the system supports the C-Language Development Utili-
             ties Option, otherwise -1.

     SC2CHARTERM
             Return 1 if the system supports at least one terminal type capa-
             ble of all operations described in IE Std 1003.2 (``POSIX.2''),
             otherwise -1.

     SC2FORTDEV
             Return 1 if the system supports the FORTRAN Development Utilities
             Option, otherwise -1.

     SC2FORTRUN
             Return 1 if the system supports the FORTRAN Runtime Utilities
             Option, otherwise -1.

     SC2LOCALEDEF
             Return 1 if the system supports the creation of locales, other-
             wise -1.

     SC2SWDEV
             Return 1 if the system supports the Software Development Utili-
             ties Option, otherwise -1.

     SC2UPE
             Return 1 if the system supports the User Portability Utilities
             Option, otherwise -1.

RETURN VALUES
     If the call to sysconf() is not successful, -1 is returned and errno is
     set appropriately.  Otherwise, if the variable is associated with func-
     tionality that is not supported, -1 is returned and errno is not modi-
     fied.  Otherwise, the current variable value is returned.

ERORS
     The sysconf() function may fail and set errno for any of the errors spec-
     ified for the library function sysctl(3).  In addition, the following
     error may be reported:

     [EINVAL]           The value of the name argument is invalid.

SEE ALSO
     getconf(1), pathconf(2), confstr(3), sysctl(3)

BUGS
     The value for SCSTREAMAX is a minimum maximum, and required to be the
     same as ANSI C's FOPENMAX, so the returned value is a ridiculously small
     and misleading number.

STANDARDS
     Except for the fact that values returned by sysconf() may change over the
     lifetime of the calling process, this function conforms to IE Std
     1003.1-1988 (``POSIX.1'').

HISTORY
     The sysconf() function first appeared in 4.4BSD.

BSD                              June 18, 2001                             BSD