SYSCONF

NAME

SYNOPSIS

#include <unistd.h>

long sysconf(int name);

DESCRIPTION

The sysconf function provides a method for an application to determined the current value of a configurable system limit or option.

The name argument represents the system variable to be queried. The following variables are supported:

Variable

name Value                     

{ARG_MAX}

{_SC_ARG_MAX}          

{CHILD_MAX}

{_SC_CHILD_MAX}                

{clock ticks/second}

{_SC_CLK_TCK}  

{NGROUPS_MAX}

{_SC_NGROUPS_MAX}              

{OPEN_MAX}

{_SC_OPEN_MAX}

{STREAM_BUF}

{_SC_STREAM_BUF}

{TZNAME_MAX}

{_SC_TZNAME_MAX}

{_POSIX_JOB_CONTROL}

{_SC_JOB_CONTROL}

{_POSIX_SAVED_IDS}

{_SC_SAVED_IDS}

{_POSIX_VERSION}

{_SC_VERSION}

The meaning of each variable is as follows:

Variable

Description

{ARG_MAX}

Maximum length of all arguments + environment strings to exec().

{CHILD_MAX}

Maximum number of simultaneous processes per real user ID.

{clock ticks/second}

The number of clock ticks per second.

{NGROUPS_MAX}

Maximum number of simultaneous supplementary group IDs per process.

{OPEN_MAX}

Maximum number of simultaneous open files per process.

{STREAM_BUF}

The number of streams that one process can have open at one time.

{TZNAME_MAX}

The maximum number of bytes supported for the name of a time zone.

{_POSIX_JOB_CONTROL}

If defined, the system supports POSIX job control.

{_POSIX_SAVED_IDS}

If defined, saved set-user-IDs and set-group-IDS are supported.

{_POSIX_VERSION}

The version of POSIX supported by the system.

The values for the variables above are given in the headers <limits.h> or <unistd.h>. The symbolic constants used as values for name are given in <unistd.h>.  

RETURN VALUE

ERRORS

[EINVAL]

The value of name is invalid.

Index

NAME

SYNOPSIS

DESCRIPTION

RETURN VALUE

ERRORS