Manpage of CONFSTR

CONFSTR

Section: Linux Programmer's Manual (3)
Updated: 2015-08-08
Index
 

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 nameargument is the system variable to be queried. The following variables are supported:

_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 PATHvariable which indicates where all the POSIX.2 standard utilities can be found.

If bufis not NULL and lenis not zero, confstr() copies the value of the string to buftruncated to len - 1bytes if necessary, with a null byte (aq\0aq) as terminator. This can be detected by comparing the return value of confstr() against len.

If lenis zero and bufis NULL, confstr() just returns the value as defined below.  

RETURN VALUE

If nameis a valid configuration variable, 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 greater than len, which means that the value in bufis truncated.

If nameis a valid configuration variable, but that variable does not have a value, then confstr() returns 0. If namedoes not correspond to a valid configuration variable, confstr() returns 0, and errnois set to EINVAL.  

ERRORS

EINVAL
The value of nameis invalid.
 

ATTRIBUTES

For an explanation of the terms used in this section, see attributes(7).
InterfaceAttributeValue
confstr() Thread safetyMT-Safe
 

CONFORMING TO

POSIX.1-2001, POSIX.1-2008.  

EXAMPLE

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);
 

SEE ALSO

getconf(1), sh(1), exec(3), fpathconf(3), pathconf(3), sysconf(3), system(3)


 

Index

NAME
SYNOPSIS
DESCRIPTION
RETURN VALUE
ERRORS
ATTRIBUTES
CONFORMING TO
EXAMPLE
SEE ALSO

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