1.\" Copyright (c) 1993 The Regents of the University of California. 2.\" All rights reserved. 3.\" 4.\" %sccs.include.redist.roff% 5.\" 6.\" @(#)sysconf.3 5.1 (Berkeley) 05/24/93 7.\" 8.Dd 9.Dt SYSCONF 3 10.Os BSD 4 11.Sh NAME 12.Nm sysconf 13.Nd get configurable system variables 14.Sh SYNOPSIS 15.Fd #include <unistd.h> 16.Ft long 17.Fn sysconf "int name" 18.Sh DESCRIPTION 19.Bf -symbolic 20This interface is obsoleted by sysctl(3). 21.Ef 22.Pp 23The 24.Fn sysconf 25function provides a method for applications to determine the current 26value of a configurable system limit or option variable. 27The 28.Fa name 29argument specifies the system variable to be queried. 30Symbolic constants for each name value are found in the include file 31.Li <unistd.h> . 32.Pp 33The available values are as follows: 34.Pp 35.Bl -tag -width "123456" 36.Pp 37.It Li _SC_ARG_MAX 38The maximum bytes of argument to 39.Xr exec 2 . 40.It Li _SC_CHILD_MAX 41The maximum number of simultaneous processes per user id. 42.It Li _SC_CLK_TCK 43Number of micro-seconds per hz tick. 44.It Li _SC_NGROUPS_MAX 45The maximum number of supplemental groups. 46.It Li _SC_OPEN_MAX 47The maximum number of open files per user id. 48.It Li _SC_STREAM_MAX 49The minimum maximum number of streams that a process may have open 50at any one time. 51.It Li _SC_TZNAME_MAX 52The minimum maximum number of types supported for the name of a 53timezone. 54.It Li _SC_JOB_CONTROL 55Return 1 if job control is available on this system, otherwise \-1. 56.It Li _SC_SAVED_IDS 57Returns 1 if saved set-group and saved set-user ID is available, 58otherwise \-1. 59.It Li _SC_VERSION 60The version of ISO/IEC 9945 (POSIX 1003.1) with which the system 61attempts to comply. 62.It Li _SC_BC_BASE_MAX 63The maximum ibase/obase values in the 64.Xr bc 1 65utility. 66.It Li _SC_BC_DIM_MAX 67The maximum array size in the 68.Xr bc 1 69utility. 70.It Li _SC_BC_SCALE_MAX 71The maximum scale value in the 72.Xr bc 1 73utility. 74.It Li _SC_BC_STRING_MAX 75The maximum string length in the 76.Xr bc 1 77utility. 78.It Li _SC_COLL_WEIGHTS_MAX 79The maximum number of weights that can be assigned to any entry of 80the LC_COLLATE order keyword in the locale definition file. 81.It Li _SC_EXPR_NEST_MAX 82The maximum number of expressions that can be nested within 83parenthesis by the 84.Xr expr 1 85utility. 86.It Li _SC_LINE_MAX 87The maximum length in bytes of a text-processing utility's input 88line. 89.It Li _SC_RE_DUP_MAX 90The maximum number of repeated occurrences of a regular expression 91permitted when using interval notation. 92.It Li _SC_2_VERSION 93The version of POSIX 1003.2 with which the system attempts to comply. 94.It Li _SC_2_C_BIND 95Return 1 if the system's C-language development facilities support the 96C-Language Bindings Option, otherwise \-1. 97.It Li _SC_2_C_DEV 98Return 1 if the system supports the C-Language Development Utilities Option, 99otherwise \-1. 100.It Li _SC_2_CHAR_TERM 101Return 1 if the system supports at least one terminal type capable of 102all operations described in POSIX 1003.2, otherwise \-1. 103.It Li _SC_2_FORT_DEV 104Return 1 if the system supports the FORTRAN Development Utilities Option, 105otherwise \-1. 106.It Li _SC_2_FORT_RUN 107Return 1 if the system supports the FORTRAN Runtime Utilities Option, 108otherwise \-1. 109.It Li _SC_2_LOCALEDEF 110Return 1 if the system supports the creation of locales, otherwise \-1. 111.It Li _SC_2_SW_DEV 112Return 1 if the system supports the Software Development Utilities Option, 113otherwise \-1. 114.It Li _SC_2_UPE 115Return 1 if the system supports the User Portability Utilities Option, 116otherwise \-1. 117.El 118.Sh RETURN VALUES 119If the call to 120.Nm sysconf 121is not successful, \-1 is returned and 122.Va errno 123is set appropriately. 124Otherwise, if the variable is associated with funtionality that is not 125supported, \-1 is returned and 126.Va errno 127is not modified. 128Otherwise, the current variable value is returned. 129.Sh ERRORS 130The 131.Fn sysconf 132function may fail and set 133.Va errno 134for any of the errors specified for the library functions 135.Xr sysctl 3 . 136In addition, the following errors may be reported: 137.Bl -tag -width Er 138.It Bq Er EINVAL 139The value of the 140.Fa name 141argument is invalid. 142.Sh SEE ALSO 143.Xr sysctl 3 144.Sh HISTORY 145The 146.Nm sysconf 147function first appeared in 4.4BSD. 148.Sh BUGS 149The value for _SC_STREAM_MAX is a minimum maximum, and required to be 150the same as ANSI C's FOPEN_MAX, so the returned value is a ridiculously 151small and misleading number. 152