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.\" $FreeBSD$ 34.\" 35.Dd April 19, 1994 36.Dt SYSCONF 3 37.Os BSD 4 38.Sh NAME 39.Nm sysconf 40.Nd get configurable system variables 41.Sh LIBRARY 42.Lb libc 43.Sh SYNOPSIS 44.Fd #include <unistd.h> 45.Ft long 46.Fn sysconf "int name" 47.Sh DESCRIPTION 48.Pp 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.Li <unistd.h> . 63.Pp 64The available values are as follows: 65.Pp 66.Bl -tag -width "123456" 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 ISO/IEC 9945 (POSIX 1003.1) with which the system 92attempts to comply. 93.It Li _SC_BC_BASE_MAX 94The maximum ibase/obase values in the 95.Xr bc 1 96utility. 97.It Li _SC_BC_DIM_MAX 98The maximum array size in the 99.Xr bc 1 100utility. 101.It Li _SC_BC_SCALE_MAX 102The maximum scale value in the 103.Xr bc 1 104utility. 105.It Li _SC_BC_STRING_MAX 106The maximum string length in the 107.Xr bc 1 108utility. 109.It Li _SC_COLL_WEIGHTS_MAX 110The maximum number of weights that can be assigned to any entry of 111the LC_COLLATE order keyword in the locale definition file. 112.It Li _SC_EXPR_NEST_MAX 113The maximum number of expressions that can be nested within 114parenthesis by the 115.Xr expr 1 116utility. 117.It Li _SC_LINE_MAX 118The maximum length in bytes of a text-processing utility's input 119line. 120.It Li _SC_RE_DUP_MAX 121The maximum number of repeated occurrences of a regular expression 122permitted when using interval notation. 123.It Li _SC_2_VERSION 124The version of POSIX 1003.2 with which the system attempts to comply. 125.It Li _SC_2_C_BIND 126Return 1 if the system's C-language development facilities support the 127C-Language Bindings Option, otherwise \-1. 128.It Li _SC_2_C_DEV 129Return 1 if the system supports the C-Language Development Utilities Option, 130otherwise \-1. 131.It Li _SC_2_CHAR_TERM 132Return 1 if the system supports at least one terminal type capable of 133all operations described in POSIX 1003.2, otherwise \-1. 134.It Li _SC_2_FORT_DEV 135Return 1 if the system supports the FORTRAN Development Utilities Option, 136otherwise \-1. 137.It Li _SC_2_FORT_RUN 138Return 1 if the system supports the FORTRAN Runtime Utilities Option, 139otherwise \-1. 140.It Li _SC_2_LOCALEDEF 141Return 1 if the system supports the creation of locales, otherwise \-1. 142.It Li _SC_2_SW_DEV 143Return 1 if the system supports the Software Development Utilities Option, 144otherwise \-1. 145.It Li _SC_2_UPE 146Return 1 if the system supports the User Portability Utilities Option, 147otherwise \-1. 148.El 149.Sh RETURN VALUES 150If the call to 151.Fn sysconf 152is not successful, \-1 is returned and 153.Va errno 154is set appropriately. 155Otherwise, if the variable is associated with functionality that is not 156supported, \-1 is returned and 157.Va errno 158is not modified. 159Otherwise, the current variable value is returned. 160.Sh ERRORS 161The 162.Fn sysconf 163function may fail and set 164.Va errno 165for any of the errors specified for the library functions 166.Xr sysctl 3 . 167In addition, the following error may be reported: 168.Bl -tag -width Er 169.It Bq Er EINVAL 170The value of the 171.Fa name 172argument is invalid. 173.Sh SEE ALSO 174.Xr sysctl 3 175.Sh BUGS 176The value for _SC_STREAM_MAX is a minimum maximum, and required to be 177the same as ANSI C's FOPEN_MAX, so the returned value is a ridiculously 178small and misleading number. 179.Sh STANDARDS 180Except for the fact that values returned by 181.Fn sysconf 182may change over the lifetime of the calling process, 183this function conforms to 184.St -p1003.1-88 . 185.Sh HISTORY 186The 187.Fn sysconf 188function first appeared in 189.Bx 4.4 . 190