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 SYNOPSIS 42.Fd #include <unistd.h> 43.Ft long 44.Fn sysconf "int name" 45.Sh DESCRIPTION 46.Pp 47This interface is defined by 48.St -p1003.1-88 . 49A far more complete interface is available using 50.Xr sysctl 3 . 51.Pp 52The 53.Fn sysconf 54function provides a method for applications to determine the current 55value of a configurable system limit or option variable. 56The 57.Fa name 58argument specifies the system variable to be queried. 59Symbolic constants for each name value are found in the include file 60.Li <unistd.h> . 61.Pp 62The available values are as follows: 63.Pp 64.Bl -tag -width "123456" 65.Pp 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_NGROUPS_MAX 74The maximum number of supplemental groups. 75.It Li _SC_OPEN_MAX 76The maximum number of open files per user id. 77.It Li _SC_STREAM_MAX 78The minimum maximum number of streams that a process may have open 79at any one time. 80.It Li _SC_TZNAME_MAX 81The minimum maximum number of types supported for the name of a 82timezone. 83.It Li _SC_JOB_CONTROL 84Return 1 if job control is available on this system, otherwise \-1. 85.It Li _SC_SAVED_IDS 86Returns 1 if saved set-group and saved set-user ID is available, 87otherwise \-1. 88.It Li _SC_VERSION 89The version of ISO/IEC 9945 (POSIX 1003.1) with which the system 90attempts to comply. 91.It Li _SC_BC_BASE_MAX 92The maximum ibase/obase values in the 93.Xr bc 1 94utility. 95.It Li _SC_BC_DIM_MAX 96The maximum array size in the 97.Xr bc 1 98utility. 99.It Li _SC_BC_SCALE_MAX 100The maximum scale value in the 101.Xr bc 1 102utility. 103.It Li _SC_BC_STRING_MAX 104The maximum string length in the 105.Xr bc 1 106utility. 107.It Li _SC_COLL_WEIGHTS_MAX 108The maximum number of weights that can be assigned to any entry of 109the LC_COLLATE order keyword in the locale definition file. 110.It Li _SC_EXPR_NEST_MAX 111The maximum number of expressions that can be nested within 112parenthesis by the 113.Xr expr 1 114utility. 115.It Li _SC_LINE_MAX 116The maximum length in bytes of a text-processing utility's input 117line. 118.It Li _SC_RE_DUP_MAX 119The maximum number of repeated occurrences of a regular expression 120permitted when using interval notation. 121.It Li _SC_2_VERSION 122The version of POSIX 1003.2 with which the system attempts to comply. 123.It Li _SC_2_C_BIND 124Return 1 if the system's C-language development facilities support the 125C-Language Bindings Option, otherwise \-1. 126.It Li _SC_2_C_DEV 127Return 1 if the system supports the C-Language Development Utilities Option, 128otherwise \-1. 129.It Li _SC_2_CHAR_TERM 130Return 1 if the system supports at least one terminal type capable of 131all operations described in POSIX 1003.2, otherwise \-1. 132.It Li _SC_2_FORT_DEV 133Return 1 if the system supports the FORTRAN Development Utilities Option, 134otherwise \-1. 135.It Li _SC_2_FORT_RUN 136Return 1 if the system supports the FORTRAN Runtime Utilities Option, 137otherwise \-1. 138.It Li _SC_2_LOCALEDEF 139Return 1 if the system supports the creation of locales, otherwise \-1. 140.It Li _SC_2_SW_DEV 141Return 1 if the system supports the Software Development Utilities Option, 142otherwise \-1. 143.It Li _SC_2_UPE 144Return 1 if the system supports the User Portability Utilities Option, 145otherwise \-1. 146.El 147.Sh RETURN VALUES 148If the call to 149.Fn sysconf 150is not successful, \-1 is returned and 151.Va errno 152is set appropriately. 153Otherwise, if the variable is associated with functionality that is not 154supported, \-1 is returned and 155.Va errno 156is not modified. 157Otherwise, the current variable value is returned. 158.Sh ERRORS 159The 160.Fn sysconf 161function may fail and set 162.Va errno 163for any of the errors specified for the library functions 164.Xr sysctl 3 . 165In addition, the following error may be reported: 166.Bl -tag -width Er 167.It Bq Er EINVAL 168The value of the 169.Fa name 170argument is invalid. 171.Sh SEE ALSO 172.Xr sysctl 3 173.Sh BUGS 174The value for _SC_STREAM_MAX is a minimum maximum, and required to be 175the same as ANSI C's FOPEN_MAX, so the returned value is a ridiculously 176small and misleading number. 177.Sh STANDARDS 178Except for the fact that values returned by 179.Fn sysconf 180may change over the lifetime of the calling process, 181this function conforms to 182.St -p1003.1-88 . 183.Sh HISTORY 184The 185.Fn sysconf 186function first appeared in 187.Bx 4.4 . 188