CLEARENV(3)CLEARENV(3)NAME
clearenv - clear the environment
SYNOPSIS
#include <stdlib.h>
int clearenv(void);
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 non-zero value
on failure.
AVAILABILITY
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(), 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(),
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 manpages write: If environ has been modified by
anything other than the putenv(), getenv(), or clearenv() functions,
then clearenv() will return an error and the process environment will
remain unchanged.
SEE ALSOgetenv(3), putenv(3), setenv(3), unsetenv(3), environ(7)Linux Programmer's Manual 2001-10-17 CLEARENV(3)