Name
clearenv — clear the environment
Synopsis
#include <stdlib.h>
int
clearenv( |
void); |
![[Note]](../stylesheet/note.png) |
Note | ||
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DESCRIPTION
The clearenv() function
clears the environment of all name-value pairs and sets the
value of the external variable environ to NULL.
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.
COLOPHON
This page is part of release 2.79 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/.
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Copyright 2001 John Levon <mozcompsoc.man.ac.uk> Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one. Since the Linux kernel and libraries are constantly changing, this manual page may be incorrect or out-of-date. The author(s) assume no responsibility for errors or omissions, or for damages resulting from the use of the information contained herein. The author(s) may not have taken the same level of care in the production of this manual, which is licensed free of charge, as they might when working professionally. Formatted or processed versions of this manual, if unaccompanied by the source, must acknowledge the copyright and authors of this work. Additions, aeb, 2001-10-17. |