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Neither the name of the University nor the names of its contributors .\" may be used to endorse or promote products derived from this software .\" without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .\" @(#)sysconf.3 8.3 (Berkeley) 4/19/94 .\" $FreeBSD: src/lib/libc/gen/sysconf.3,v 1.25 2007/01/09 00:27:55 imp Exp $ .\" .Dd December 14, 2006 .Dt SYSCONF 3 .Os .Sh NAME .Nm sysconf .Nd get configurable system variables .Sh LIBRARY .Lb libc .Sh SYNOPSIS .In unistd.h .Ft long .Fn sysconf "int name" .Sh DESCRIPTION This interface is defined by .St -p1003.1-88 . A far more complete interface is available using .Xr sysctl 3 . .Pp The .Fn sysconf function provides a method for applications to determine the current value of a configurable system limit or option variable. The .Fa name argument specifies the system variable to be queried. Symbolic constants for each name value are found in the include file .In unistd.h . Shell programmers who need access to these parameters should use the .Xr getconf 1 utility. .Pp The available values are as follows: .Pp .Bl -tag -width 6n .Pp .It Li _SC_ARG_MAX The maximum bytes of argument to .Xr execve 2 . .It Li _SC_CHILD_MAX The maximum number of simultaneous processes per user id. .It Li _SC_CLK_TCK The frequency of the statistics clock in ticks per second. .It Li _SC_IOV_MAX The maximum number of elements in the I/O vector used by .Xr readv 2 , .Xr writev 2 , .Xr recvmsg 2 , and .Xr sendmsg 2 . .It Li _SC_NGROUPS_MAX The maximum number of supplemental groups. .It Li _SC_NPROCESSORS_CONF The number of processors configured. .It Li _SC_NPROCESSORS_ONLN The number of processors currently online. .It Li _SC_OPEN_MAX The maximum number of open files per user id. .It Li _SC_PAGESIZE The size of a system page in bytes. .It Li _SC_STREAM_MAX The minimum maximum number of streams that a process may have open at any one time. .It Li _SC_TZNAME_MAX The minimum maximum number of types supported for the name of a timezone. .It Li _SC_JOB_CONTROL Return 1 if job control is available on this system, otherwise \-1. .It Li _SC_SAVED_IDS Returns 1 if saved set-group and saved set-user ID is available, otherwise \-1. .It Li _SC_VERSION The version of .St -p1003.1 with which the system attempts to comply. .It Li _SC_BC_BASE_MAX The maximum ibase/obase values in the .Xr bc 1 utility. .It Li _SC_BC_DIM_MAX The maximum array size in the .Xr bc 1 utility. .It Li _SC_BC_SCALE_MAX The maximum scale value in the .Xr bc 1 utility. .It Li _SC_BC_STRING_MAX The maximum string length in the .Xr bc 1 utility. .It Li _SC_COLL_WEIGHTS_MAX The maximum number of weights that can be assigned to any entry of the LC_COLLATE order keyword in the locale definition file. .It Li _SC_EXPR_NEST_MAX The maximum number of expressions that can be nested within parenthesis by the .Xr expr 1 utility. .It Li _SC_LINE_MAX The maximum length in bytes of a text-processing utility's input line. .It Li _SC_RE_DUP_MAX The maximum number of repeated occurrences of a regular expression permitted when using interval notation. .It Li _SC_2_VERSION The version of .St -p1003.2 with which the system attempts to comply. .It Li _SC_2_C_BIND Return 1 if the system's C-language development facilities support the C-Language Bindings Option, otherwise \-1. .It Li _SC_2_C_DEV Return 1 if the system supports the C-Language Development Utilities Option, otherwise \-1. .It Li _SC_2_CHAR_TERM Return 1 if the system supports at least one terminal type capable of all operations described in .St -p1003.2 , otherwise \-1. .It Li _SC_2_FORT_DEV Return 1 if the system supports the FORTRAN Development Utilities Option, otherwise \-1. .It Li _SC_2_FORT_RUN Return 1 if the system supports the FORTRAN Runtime Utilities Option, otherwise \-1. .It Li _SC_2_LOCALEDEF Return 1 if the system supports the creation of locales, otherwise \-1. .It Li _SC_2_SW_DEV Return 1 if the system supports the Software Development Utilities Option, otherwise \-1. .It Li _SC_2_UPE Return 1 if the system supports the User Portability Utilities Option, otherwise \-1. .El .Pp These values also exist, but may not be standard: .Pp .Bl -tag -width 6n .Pp .It Li _SC_PHYS_PAGES The number of pages of physical memory. Note that it is possible that the product of this value and the value of .Li _SC_PAGESIZE will overflow a .Vt long in some configurations on a 32bit machine. .El .Sh RETURN VALUES If the call to .Fn sysconf is not successful, \-1 is returned and .Va errno is set appropriately. Otherwise, if the variable is associated with functionality that is not supported, \-1 is returned and .Va errno is not modified. Otherwise, the current variable value is returned. .Sh ERRORS The .Fn sysconf function may fail and set .Va errno for any of the errors specified for the library function .Xr sysctl 3 . In addition, the following error may be reported: .Bl -tag -width Er .It Bq Er EINVAL The value of the .Fa name argument is invalid. .El .Sh SEE ALSO .Xr getconf 1 , .Xr pathconf 2 , .Xr confstr 3 , .Xr sysctl 3 .Sh STANDARDS Except for the fact that values returned by .Fn sysconf may change over the lifetime of the calling process, this function conforms to .St -p1003.1-88 . .Sh HISTORY The .Fn sysconf function first appeared in .Bx 4.4 . .Sh BUGS The value for _SC_STREAM_MAX is a minimum maximum, and required to be the same as ANSI C's FOPEN_MAX, so the returned value is a ridiculously small and misleading number.