Section (3) confstr
confstr — get configuration dependent string variables
confstr() gets the value of
configuration-dependent string variables.
is the system variable to be queried. The following variables
_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).
A value for the
PATHvariable which indicates where all the POSIX.2 standard utilities can be found.
buf is not NULL
len is not zero,
confstr() copies the value of
the string to
truncated to len −
1 bytes if necessary, with a null byte (_zsingle_quotesz_ _zsingle_quotesz_) as
terminator. This can be detected by comparing the return
len is zero and
buf is NULL,
confstr() just returns the
value as defined below.
name is a valid
confstr() returns the number of bytes
(including the terminating null byte) that would be required
to hold the entire value of that variable. This value may be
which means that the value in
buf is truncated.
name is a valid
configuration variable, but that variable does not have a
name does not
correspond to a valid configuration variable,
confstr() returns 0, and
errno is set to EINVAL.
For an explanation of the terms used in this section, see attributes(7).
The following code fragment determines the path where to find the POSIX.2 system utilities:
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);
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Copyright (c) 1993 by Thomas Koenig (ig25rz.uni-karlsruhe.de)
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Formatted or processed versions of this manual, if unaccompanied by
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Modified Sat Jul 24 19:53:02 1993 by Rik Faith (faithcs.unc.edu)
FIXME Many more values for _zsingle_quotesz_name_zsingle_quotesz_ are supported, some of which
are documented under _zsingle_quotesz_info confstr_zsingle_quotesz_.
See <bits/confname.h> for the rest.
These should all be added to this page.
See also the POSIX.1-2001 specification of confstr()