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 1.2 2003/06/17 04:26:42 dillon Exp $ 35.\" 36.Dd April 19, 1994 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.Aq Pa unistd.h . 63.Pp 64The available values are as follows: 65.Pp 66.Bl -tag -width 6n 67.Pp 68.It Li _SC_ARG_MAX 69The maximum bytes of argument to 70.Xr execve 2 . 71.It Li _SC_CHILD_MAX 72The maximum number of simultaneous processes per user id. 73.It Li _SC_CLK_TCK 74The frequency of the statistics clock in ticks per second. 75.It Li _SC_NGROUPS_MAX 76The maximum number of supplemental groups. 77.It Li _SC_OPEN_MAX 78The maximum number of open files per user id. 79.It Li _SC_STREAM_MAX 80The minimum maximum number of streams that a process may have open 81at any one time. 82.It Li _SC_TZNAME_MAX 83The minimum maximum number of types supported for the name of a 84timezone. 85.It Li _SC_JOB_CONTROL 86Return 1 if job control is available on this system, otherwise \-1. 87.It Li _SC_SAVED_IDS 88Returns 1 if saved set-group and saved set-user ID is available, 89otherwise \-1. 90.It Li _SC_VERSION 91The version of 92.St -p1003.1 93with which the system 94attempts to comply. 95.It Li _SC_BC_BASE_MAX 96The maximum ibase/obase values in the 97.Xr bc 1 98utility. 99.It Li _SC_BC_DIM_MAX 100The maximum array size in the 101.Xr bc 1 102utility. 103.It Li _SC_BC_SCALE_MAX 104The maximum scale value in the 105.Xr bc 1 106utility. 107.It Li _SC_BC_STRING_MAX 108The maximum string length in the 109.Xr bc 1 110utility. 111.It Li _SC_COLL_WEIGHTS_MAX 112The maximum number of weights that can be assigned to any entry of 113the LC_COLLATE order keyword in the locale definition file. 114.It Li _SC_EXPR_NEST_MAX 115The maximum number of expressions that can be nested within 116parenthesis by the 117.Xr expr 1 118utility. 119.It Li _SC_LINE_MAX 120The maximum length in bytes of a text-processing utility's input 121line. 122.It Li _SC_RE_DUP_MAX 123The maximum number of repeated occurrences of a regular expression 124permitted when using interval notation. 125.It Li _SC_2_VERSION 126The version of 127.St -p1003.2 128with which the system attempts to comply. 129.It Li _SC_2_C_BIND 130Return 1 if the system's C-language development facilities support the 131C-Language Bindings Option, otherwise \-1. 132.It Li _SC_2_C_DEV 133Return 1 if the system supports the C-Language Development Utilities Option, 134otherwise \-1. 135.It Li _SC_2_CHAR_TERM 136Return 1 if the system supports at least one terminal type capable of 137all operations described in 138.St -p1003.2 , 139otherwise \-1. 140.It Li _SC_2_FORT_DEV 141Return 1 if the system supports the FORTRAN Development Utilities Option, 142otherwise \-1. 143.It Li _SC_2_FORT_RUN 144Return 1 if the system supports the FORTRAN Runtime Utilities Option, 145otherwise \-1. 146.It Li _SC_2_LOCALEDEF 147Return 1 if the system supports the creation of locales, otherwise \-1. 148.It Li _SC_2_SW_DEV 149Return 1 if the system supports the Software Development Utilities Option, 150otherwise \-1. 151.It Li _SC_2_UPE 152Return 1 if the system supports the User Portability Utilities Option, 153otherwise \-1. 154.El 155.Sh RETURN VALUES 156If the call to 157.Fn sysconf 158is not successful, \-1 is returned and 159.Va errno 160is set appropriately. 161Otherwise, if the variable is associated with functionality that is not 162supported, \-1 is returned and 163.Va errno 164is not modified. 165Otherwise, the current variable value is returned. 166.Sh ERRORS 167The 168.Fn sysconf 169function may fail and set 170.Va errno 171for any of the errors specified for the library function 172.Xr sysctl 3 . 173In addition, the following error may be reported: 174.Bl -tag -width Er 175.It Bq Er EINVAL 176The value of the 177.Fa name 178argument is invalid. 179.El 180.Sh SEE ALSO 181.Xr sysctl 3 182.Sh BUGS 183The value for _SC_STREAM_MAX is a minimum maximum, and required to be 184the same as ANSI C's FOPEN_MAX, so the returned value is a ridiculously 185small and misleading number. 186.Sh STANDARDS 187Except for the fact that values returned by 188.Fn sysconf 189may change over the lifetime of the calling process, 190this function conforms to 191.St -p1003.1-88 . 192.Sh HISTORY 193The 194.Fn sysconf 195function first appeared in 196.Bx 4.4 . 197