Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
clearenv(): _SVID_SOURCE || _BSD_SOURCE
The clearenv() function clears the environment of all name-value pairs
and sets the value of the external variable environ to NULL.
The clearenv() function returns zero on success, and a nonzero value on
Not in libc4, libc5. In glibc since glibc 2.0.
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().
Used in security-conscious applications. If it is unavailable the
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
getenv(3), putenv(3), setenv(3), unsetenv(3), environ(7)
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/.
Linux 2010-10-04 CLEARENV(3)
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