Name

sysconf − get configurable system variables (POSIX)

Syntax

#include <unistd.h>

long sysconf(name)
int name;

Description

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

The name argument represents the system variable to be queried. The following table lists the system variables which may be queried and the corresponding value for the name argument. The values for the name argument are defined in the <unistd.h> header file. 

Variable                     name Value
 ARG_MAX                      _SC_ARG_MAX
CHILD_MAX                    _SC_CHILD_MAX
CLK_TCK                      _SC_CLK_TCK
NGROUPS_MAX                  _SC_NGROUPS_MAX
OPEN_MAX                     _SC_OPEN_MAX
PASS_MAX                     _SC_PASS_MAX
_POSIX_JOB_CONTROL           _SC_JOB_CONTROL
_POSIX_SAVED_IDS             _SC_SAVED_IDS
_POSIX_VERSION               _SC_VERSION
_XOPEN_VERSION               _SC_XOPEN_VERSION

Return Values

Upon successful completion, the sysconf function returns the current variable value on the system.

If name is an invalid value, sysconf returns −1 and errno is set to indicate the reason. If the variable corresponding to name is not defined on the system, sysconf returns −1 without changing the value of errno. 

Diagnostics

The sysconf function fails if the following occurs:

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