NAME

       clearenv - clear the environment

SYNOPSIS

       #include <stdlib.h>

       int clearenv(void);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       clearenv(): _SVID_SOURCE || _BSD_SOURCE

DESCRIPTION

       The clearenv() function clears the environment of all name-value pairs and sets the value of the external
       variable environ to NULL.

RETURN VALUE

       The clearenv() function returns zero on success, and a nonzero value on failure.

VERSIONS

       Not in libc4, libc5.  In glibc since glibc 2.0.

CONFORMING TO

       Various UNIX variants (DG/UX, HP-UX, QNX, ...).  POSIX.9 (bindings for FORTRAN77).  POSIX.1-1996 did  not
       accept  clearenv() and putenv(3), but changed its mind and scheduled these functions for some later issue
       of this standard (cf. B.4.6.1).  However, POSIX.1-2001 adds only putenv(3), and rejected clearenv().

NOTES

       Used in security-conscious applications.  If it is unavailable the assignment

           environ = NULL;

       will probably do.

       The DG/UX and Tru64 man pages write: If environ has been modified by anything other than  the  putenv(3),
       getenv(3), or clearenv() functions, then clearenv() will return an error and the process environment will
       remain unchanged.

SEE ALSO

       getenv(3), putenv(3), setenv(3), unsetenv(3), environ(7)

COLOPHON

       This page is part of release 3.54 of the Linux man-pages project.  A  description  of  the  project,  and
       information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.