sysconf(3C) — C LIBRARY FUNCTIONS

NAME

sysconf − retrieves configurable system variables

SYNOPSIS

#include <unistd.h>
long sysconf(int name);

DESCRIPTION

Multiprocessing supports the following new name values:

_SC_NPROC_CONF
Number of currently configured processors.

_SC_NPROC_ONLN
Number of processors currently online.

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

The name argument represents the system variable to be queried. The following table lists the minimal set of system variables from limits.h and unistd.h that can be returned by sysconf, and the symbolic constants, defined in unistd.h that are the corresponding values used for name.

NAME	RETURN VALUE


_SC_CHILD_MAX	CHILD_MAX
_SC_CLK_TCK	CLK_TCK
_SC_NGROUPS_MAX	NGROUPS_MAX
_SC_OPEN_MAX	OPEN_MAX
_SC_PASS_MAX	PASS_MAX
_SC_PAGESIZE	PAGESIZE
_SC_JOB_CONTROL	_POSIX_JOB_CONTROL
_SC_SAVED_IDS	_POSIX_SAVED_IDS
_SC_VERSION	_POSIX_VERSION
_SC_XOPEN_VERSION	_XOPEN_VERSION
_SC_LOGNAME_MAX	LOGNAME_MAX
_SC_NPROC_CONF	# configured processors
_SC_NPROC_ONLN	# processors online
_SC_ARCH_VERSION	# 0 on 88100, 1 on 88110

The value of CLK_TCK may be variable and it should not be assumed that CLK_TCK is a compile-time constant. The value of CLK_TCK is the same as the value of sysconf(_SC_CLK_TCK).

The unique system identifier returned by sysconf (_SC_BCS_SYS_ID) is determined as follows: If there is a valid system serial number loaded into the NVRAM on the cpu board, then that serial number will be returned. Otherwise, the lower four bytes of the unique Ethernet address of the Ethernet board with the lowest board type will be returned. If two or more Ethernet boards have the same lowest board type, the address of the board with the lowest board type with the lowest minor device value will be returned.

For example, given this configuration:

Board	Minor Device	Ethernet Address
MVME376	0	0x10000000
MVME374	1	0x20000000
MVME374	0	0x30000000

sysconf(_SC_BCS_SYS_ID) returns: 0x30000000

This algorithm can be overridden by uadmin(1M). See the Release Notes for details.

DIAGNOSTICS

sysconf returns the appropriate value on success, or a negative value on failure.

Failure may result from:

EINVAL The name argument is invalid.

If name is an invalid value, sysconf will return −1 and set errno to indicate the error. If sysconf fails due to a value of name that is not defined on the system, the function will return a value of −1 without changing the value of errno.

NOTES

A call to setrlimit may cause the value of OPEN_MAX to change.

Museum