confstr(3) [freebsd man page]

CONFSTR(3)						   BSD Library Functions Manual 						CONFSTR(3)

NAME

     confstr -- get string-valued configurable variables

LIBRARY

     Standard C Library (libc, -lc)

SYNOPSIS

     #include <unistd.h>

     size_t
     confstr(int name, char *buf, size_t len);

DESCRIPTION

     This interface is specified by IEEE Std 1003.1-2001 (``POSIX.1'').  A more flexible (but non-portable) interface is provided by sysctl(3).

     The confstr() function provides a method for applications to get configuration defined string values.  Shell programmers needing access to
     these parameters should use the getconf(1) utility.

     The name argument specifies the system variable to be queried.  Symbolic constants for each name value are found in the include file
     <unistd.h>.  The len argument specifies the size of the buffer referenced by the argument buf.  If len is non-zero, buf is a non-null
     pointer, and name has a value, up to len - 1 bytes of the value are copied into the buffer buf.  The copied value is always null terminated.

     The available values are as follows:

     _CS_PATH
	     Return a value for the PATH environment variable that finds all the standard utilities.

RETURN VALUES

     If the call to confstr() is not successful, 0 is returned and errno is set appropriately.	Otherwise, if the variable does not have a config-
     uration defined value, 0 is returned and errno is not modified.  Otherwise, the buffer size needed to hold the entire configuration-defined
     value is returned.  If this size is greater than the argument len, the string in buf was truncated.

ERRORS

     The confstr() function may fail and set errno for any of the errors specified for the library functions malloc(3) and sysctl(3).

     In addition, the following errors may be reported:

     [EINVAL]		The value of the name argument is invalid.

SEE ALSO

     getconf(1), pathconf(2), sysconf(3), sysctl(3)

HISTORY

     The confstr() function first appeared in 4.4BSD.

BSD
								 December 3, 2006							       BSD

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 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 PATH variable which indicates where all the POSIX.2 standard utilities 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 ('') 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 (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 buf is truncated.

       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, confstr() 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 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)

COLOPHON

       This page is part of release 4.15 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 https://www.kernel.org/doc/man-pages/.

GNU                                                                 2017-09-15                                                          CONFSTR(3)