sysconf.3

来自「<B>Digital的Unix操作系统VAX 4.2源码</B>」· 3 代码 · 共 66 行

.\" SCCSID: @(#)sysconf.3	2.3	8/10/87
.TH sysconf 3
.SH Name
sysconf \- get configurable system variables (POSIX)
.SH Syntax
.nf
.B #include <unistd.h>
.PP
.B long sysconf(\fIname\fP)
.B int \fIname\fP;
.br
.SH Description
The
.PN sysconf
function provides a method for the application to determine the current
value of a configurable system limit or option.
.NXR "sysconf subroutine"
.PP
The 
.IR 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
.IR name
argument. The values for the
.IR name
argument are defined in the <unistd.h> header file.
.EX
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
.EE
.SH Return Values
Upon successful completion, the
.PN sysconf 
function returns the current variable value on the system.
.PP
If 
.IR name
is an invalid value,
.PN sysconf 
returns \-1 and 
.I errno
is set to indicate the reason. If the variable corresponding to
.IR name
is not defined on the system,
.PN sysconf 
returns \-1 without changing the value of
.I errno.
.SH Diagnostics
The
.PN sysconf 
function fails if the following occurs:
.TP 15
[EINVAL]
The value of the \fIname\fP argument is invalid.