CLEARENV
Section: Linux Programmer's Manual (3)
Updated: 2007-07-26
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 || _XOPEN_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
only adds
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 3.27 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/.
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUE
-
- VERSIONS
-
- CONFORMING TO
-
- NOTES
-
- SEE ALSO
-
- COLOPHON
-
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Time: 07:35:05 GMT, March 26, 2013