.\" (c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de) .\" .\" Permission is granted to make and distribute verbatim copies of this .\" manual provided the copyright notice and this permission notice are .\" preserved on all copies. .\" .\" Permission is granted to copy and distribute modified versions of this .\" manual under the conditions for verbatim copying, provided that the .\" entire resulting derived work is distributed under the terms of a .\" permission notice identical to this one .\" .\" Since the Linux kernel and libraries are constantly changing, this .\" manual page may be incorrect or out-of-date. The author(s) assume no .\" responsibility for errors or omissions, or for damages resulting from .\" the use of the information contained herein. The author(s) may not .\" have taken the same level of care in the production of this manual, .\" which is licensed free of charge, as they might when working .\" professionally. .\" .\" Formatted or processed versions of this manual, if unaccompanied by .\" the source, must acknowledge the copyright and authors of this work. .\" License. .\" Modified Sat Jul 24 17:51:42 1993 by Rik Faith (faith@cs.unc.edu) .TH SYSCONF 3 "April 18, 1993" "GNU" "Linux Programmer's Manual" .SH NAME sysconf \- Get configuration information at runtime .SH SYNOPSIS .nf .B #include .sp .BI "long sysconf(int " "name" ");" .fi .SH DESCRIPTION .B sysconf() provides a way for the application to determine values for system limits or options at runtime. .PP The equivalent macros defined in .B can only give conservative values; if an application wants to take advantage of values which may change, a call to .B sysconf() can be made, which may yield more liberal results. .PP For getting information about a particular file, see .BR fpathconf() " or " pathconf() . .PP The following values are supported for .IR name . First, the POSIX.1 compatible values: .TP .B _SC_ARG_MAX The maximum length of the arguments to the .B exec() family of functions; the corresponding macro is .BR ARG_MAX . .TP .B _SC_CHILD_MAX The number of simultaneous processes per user id, the corresponding macro is .BR _POSIX_CHILD_MAX . .TP .B _SC_CLK_TCK The number of clock ticks per second; the corresponding macro is .BR CLK_TCK . .TP .B _SC_STREAM_MAX The maximum number of streams that a process can have open at any time. The corresponding POSIX macro is .BR STREAM_MAX , the corresponding standard C macro is .BR FOPEN_MAX . .TP .B _SC_TZNAME_MAX The maximum number of bytes in a timezone name, the corresponding macro is .BR TZNAME_MAX . .TP .B _SC_OPEN_MAX The maximum number of files that a process can have open at any time, the corresponding macro is .BR _POSIX_OPEN_MAX . .TP .B _SC_JOB_CONTROL This indicates whether POSIX \- style job control is supported, the corresponding macro is .BR _POSIX_JOB_CONTROL . .TP .B _SC_SAVED_IDS This indicates whether a process has a saved set-user-ID and a saved set-group-ID; the corresponding macro is .BR _POSIX_SAVED_IDS . .TP .B _SC_VERSION indicates the year and month the POSIX.1 standard was approved in the format .BR YYYYMML ; the value .B 199009L indicates the most recent revision, 1990. .PP Next, the POSIX.2 values: .TP .B _SC_BC_BASE_MAX indicates the maximum .I obase value accepted by the .BR bc (1) utility; the corresponding macro is .BR BC_BASE_MAX . .TP .B _SC_BC_DIM_MAX indicates the maximum value of elements permitted in an array by .BR bc (1); the corresponding macro is .BR BC_DIM_MAX . .TP .B _SC_BC_SCALE_MAX indicates the maximum .I scale value allowed by .BR bc (1); the corresponding macro is .BR BC_SCALE_MAX . .TP .B _SC_BC_STRING_MAX indicates the maximum length of a string accepted by .BR bc (1); the corresponding macro is .BR BC_STRING_MAX . .TP .B _SC_COLL_WEIGHTS_MAX indicates the maximum numbers of weights that can be assigned to an entry of the .B LC_COLLATE order keyword in the locale definition file; the corresponding macro is .BR COLL_WEIGHTS_MAX . .TP .B _SC_EXPR_NEST_MAX is the maximum number of expressions which can be nested within parentheses by .BR expr (1). The corresponding macro is .BR EXPR_NEST_MAX . .TP .B _SC_LINE_MAX The maximum length of a utility's input line length, either from standard input or from a file. This includes length for a trailing newline. The corresponding macro is .BR LINE_MAX . .TP .B _SC_RE_DUP_MAX The maximum number of repeated occurrences of a regular expression when the interval notation .B \e{m,n\e} is used. The value of the corresponding macro is .BR RE_DUP_MAX . .TP .B _SC_2_VERSION indicates the version of the POSIX.2 standard in the format of YYYYMML. The corresponding macro is .BR POSIX2_VERSION . .TP .B _SC_2_DEV indicates whether the POSIX.2 C language development facilities are supported. The corresponding macro is .BR POSIX2_C_DEV . .TP .B _SC_2_FORT_DEV indicates whether the POSIX.2 FORTRAN development utilities are supported. The corresponding macro is .BR POSIX2_FORT_RUN . .TP .B _SC_2_FORT_RUN indicates whether the POSIX.2 FORTRAN runtime utilities are supported. The corresponding macro is .BR POSIX2_FORT_RUN . .TP .B _SC_2_LOCALEDEF indicates whether the POSIX.2 creation of locates via .BR localedef (1) is supported. The corresponding macro is .BR _POSIX2_LOCALEDEF . .TP .B _SC_2_SW_DEV indicates whether the POSIX.2 software development utilities option is supported. The corresponding macro is .BR POSIX2_SW_DEV . .SH "RETURN VALUE" The value returned is the value of the system resource, 1 if a queried option is available, 0 if it is not, or \-1 on error. The variable .I errno is not set. .SH "CONFORMING TO" POSIX.1, proposed POSIX.2 .SH "BUGS" It is difficult to use .B ARG_MAX because it is not specified how much of the argument space for .B exec() is consumed by the user's environment variables. .PP Some returned values may be huge; they are not suitable for allocating memory. .PP POSIX.2 is not yet an approved standard; the information in this manpage is subject to change. .SH "SEE ALSO" .BR bc "(1), " expr "(1), " locale "(1), " fpathconf "(3), " pathconf (3)