1.\" Copyright (c) 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. All advertising materials mentioning features or use of this software 13.\" must display the following acknowledgement: 14.\" This product includes software developed by the University of 15.\" California, Berkeley and its contributors. 16.\" 4. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" @(#)sysconf.3 8.3 (Berkeley) 4/19/94 33.\" $FreeBSD: src/lib/libc/gen/sysconf.3,v 1.8.2.6 2001/12/14 18:33:51 ru Exp $ 34.\" $DragonFly: src/lib/libc/gen/sysconf.3,v 1.7 2008/05/02 02:05:03 swildner Exp $ 35.\" 36.Dd February 21, 2008 37.Dt SYSCONF 3 38.Os 39.Sh NAME 40.Nm sysconf 41.Nd get configurable system variables 42.Sh LIBRARY 43.Lb libc 44.Sh SYNOPSIS 45.In unistd.h 46.Ft long 47.Fn sysconf "int name" 48.Sh DESCRIPTION 49This interface is defined by 50.St -p1003.1-88 . 51A far more complete interface is available using 52.Xr sysctl 3 . 53.Pp 54The 55.Fn sysconf 56function provides a method for applications to determine the current 57value of a configurable system limit or option variable. 58The 59.Fa name 60argument specifies the system variable to be queried. 61Symbolic constants for each name value are found in the include file 62.In unistd.h . 63.Pp 64The available values are as follows: 65.Bl -tag -width 6n 66.It Li _SC_ARG_MAX 67The maximum bytes of argument to 68.Xr execve 2 . 69.It Li _SC_CHILD_MAX 70The maximum number of simultaneous processes per user id. 71.It Li _SC_CLK_TCK 72The frequency of the statistics clock in ticks per second. 73.It Li _SC_IOV_MAX 74The maximum number of elements in the I/O vector used by 75.Xr readv 2 , 76.Xr writev 2 , 77.Xr recvmsg 2 , 78and 79.Xr sendmsg 2 . 80.It Li _SC_NGROUPS_MAX 81The maximum number of supplemental groups. 82.It Li _SC_OPEN_MAX 83The maximum number of open files per user id. 84.It Li _SC_STREAM_MAX 85The minimum maximum number of streams that a process may have open 86at any one time. 87.It Li _SC_TZNAME_MAX 88The minimum maximum number of types supported for the name of a 89timezone. 90.It Li _SC_JOB_CONTROL 91Return 1 if job control is available on this system, otherwise \-1. 92.It Li _SC_SAVED_IDS 93Returns 1 if saved set-group and saved set-user ID is available, 94otherwise \-1. 95.It Li _SC_VERSION 96The version of 97.St -p1003.1 98with which the system 99attempts to comply. 100.It Li _SC_BC_BASE_MAX 101The maximum ibase/obase values in the 102.Xr bc 1 103utility. 104.It Li _SC_BC_DIM_MAX 105The maximum array size in the 106.Xr bc 1 107utility. 108.It Li _SC_BC_SCALE_MAX 109The maximum scale value in the 110.Xr bc 1 111utility. 112.It Li _SC_BC_STRING_MAX 113The maximum string length in the 114.Xr bc 1 115utility. 116.It Li _SC_COLL_WEIGHTS_MAX 117The maximum number of weights that can be assigned to any entry of 118the LC_COLLATE order keyword in the locale definition file. 119.It Li _SC_EXPR_NEST_MAX 120The maximum number of expressions that can be nested within 121parenthesis by the 122.Xr expr 1 123utility. 124.It Li _SC_LINE_MAX 125The maximum length in bytes of a text-processing utility's input 126line. 127.It Li _SC_RE_DUP_MAX 128The maximum number of repeated occurrences of a regular expression 129permitted when using interval notation. 130.It Li _SC_2_VERSION 131The version of 132.St -p1003.2 133with which the system attempts to comply. 134.It Li _SC_2_C_BIND 135Return 1 if the system's C-language development facilities support the 136C-Language Bindings Option, otherwise \-1. 137.It Li _SC_2_C_DEV 138Return 1 if the system supports the C-Language Development Utilities Option, 139otherwise \-1. 140.It Li _SC_2_CHAR_TERM 141Return 1 if the system supports at least one terminal type capable of 142all operations described in 143.St -p1003.2 , 144otherwise \-1. 145.It Li _SC_2_FORT_DEV 146Return 1 if the system supports the FORTRAN Development Utilities Option, 147otherwise \-1. 148.It Li _SC_2_FORT_RUN 149Return 1 if the system supports the FORTRAN Runtime Utilities Option, 150otherwise \-1. 151.It Li _SC_2_LOCALEDEF 152Return 1 if the system supports the creation of locales, otherwise \-1. 153.It Li _SC_2_SW_DEV 154Return 1 if the system supports the Software Development Utilities Option, 155otherwise \-1. 156.It Li _SC_2_UPE 157Return 1 if the system supports the User Portability Utilities Option, 158otherwise \-1. 159.It Li _SC_NPROCESSORS_CONF 160The number of processors configured. 161.It Li _SC_NPROCESSORS_ONLN 162The number of processors online. 163.El 164.Sh RETURN VALUES 165If the call to 166.Fn sysconf 167is not successful, \-1 is returned and 168.Va errno 169is set appropriately. 170Otherwise, if the variable is associated with functionality that is not 171supported, \-1 is returned and 172.Va errno 173is not modified. 174Otherwise, the current variable value is returned. 175.Sh ERRORS 176The 177.Fn sysconf 178function may fail and set 179.Va errno 180for any of the errors specified for the library function 181.Xr sysctl 3 . 182In addition, the following error may be reported: 183.Bl -tag -width Er 184.It Bq Er EINVAL 185The value of the 186.Fa name 187argument is invalid. 188.El 189.Sh SEE ALSO 190.Xr sysctl 3 191.Sh STANDARDS 192Except for the fact that values returned by 193.Fn sysconf 194may change over the lifetime of the calling process, 195this function conforms to 196.St -p1003.1-88 . 197.Pp 198_SC_NPROCESSORS_CONF and _SC_NPROCESSORS_ONLN are nonstandard, but implemented 199in many systems. 200.Sh HISTORY 201The 202.Fn sysconf 203function first appeared in 204.Bx 4.4 . 205.Sh BUGS 206The value for _SC_STREAM_MAX is a minimum maximum, and required to be 207the same as ANSI C's FOPEN_MAX, so the returned value is a ridiculously 208small and misleading number. 209