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CONFSTR - reference manual online

Get configuration dependent string variables.

Chapter
2015-08-08
CONFSTR(3)                          Linux Programmer's Manual                          CONFSTR(3)

NAME confstr - get configuration dependent string variables
SYNOPSIS #include <unistd.h> size_t confstr(int name, char *buf, size_t len); Feature Test Macro Requirements for glibc (see feature_test_macros(7)): confstr(): _POSIX_C_SOURCE >= 2 || _XOPEN_SOURCE
DESCRIPTION confstr() gets the value of configuration-dependent string variables. The name argument is the system variable to be queried. The following variables are sup‐ ported: _CS_GNU_LIBC_VERSION (GNU C library only; since glibc 2.3.2) A string which identifies the GNU C library version on this system (e.g, "glibc 2.3.4"). _CS_GNU_LIBPTHREAD_VERSION (GNU C library only; since glibc 2.3.2) A string which identifies the POSIX implementation supplied by this C library (e.g, "NPTL 2.3.4" or "linuxthreads-0.10"). _CS_PATH A value for the PATH variable which indicates where all the POSIX.2 standard utili‐ ties can be found. If buf is not NULL and len is not zero, confstr() copies the value of the string to buf truncated to len - 1 bytes if necessary, with a null byte ('\0') as terminator. This can be detected by comparing the return value of confstr() against len. If len is zero and buf is NULL, confstr() just returns the value as defined below.
RETURN VALUE If name is a valid configuration variable, confstr() returns the number of bytes (includ‐ ing the terminating null byte) that would be required to hold the entire value of that variable. This value may be greater than len, which means that the value in buf is trun‐ cated. If name is a valid configuration variable, but that variable does not have a value, then confstr() returns 0. If name does not correspond to a valid configuration variable, conf‐ str() returns 0, and errno is set to EINVAL.
ERRORS EINVAL The value of name is invalid.
ATTRIBUTES For an explanation of the terms used in this section, see attributes(7). ┌──────────┬───────────────┬─────────┐ │Interface │ Attribute │ Value │ ├──────────┼───────────────┼─────────┤ │confstr() │ Thread safety │ MT-Safe │ └──────────┴───────────────┴─────────┘
CONFORMING TO POSIX.1-2001, POSIX.1-2008.
EXAMPLE The following code fragment determines the path where to find the POSIX.2 system utili‐ ties: char *pathbuf; size_t n; n = confstr(_CS_PATH, NULL, (size_t) 0); pathbuf = malloc(n); if (pathbuf == NULL) abort(); confstr(_CS_PATH, pathbuf, n);
SEE ALSO getconf(1), sh(1), exec(3), fpathconf(3) sysconf(3) pathconf(3) system(3)
COLOPHON This page is part of release 4.04 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at http://www.kernel.org/doc/man-pages/.
GNU 2015-08-08 CONFSTR(3)
This manual Reference Other manuals
confstr(3) referred by exec(3) | fpathconf(3) | getconf(1) | gnu_get_libc_version(3) | posixoptions(7) | sysconf(3)
refer to attributes(7) | exec(3) | feature_test_macros(7) | fpathconf(3) | getconf(1) | fpathconf(3) | dash(1) | sysconf(3) | system(3)