php man page for putenv

PUTENV(3)								 1								 PUTENV(3)

putenv - Sets the value of an environment variable

SYNOPSIS
       bool putenv (string  $setting)

DESCRIPTION
	Adds  $setting	to the server environment. The environment variable will only exist for the duration of the current request. At the end of
       the request the environment is restored to its original state.

	Setting certain environment variables may be a potential security breach. The safe_mode_allowed_env_vars directive contains a comma-delim-
       ited  list  of  prefixes.  In Safe Mode, the user may only alter environment variables whose names begin with the prefixes supplied by this
       directive. By default, users will only be able to set environment variables that begin with PHP_ (e.g.  PHP_FOO=BAR). Note: if this  direc-
       tive is empty, PHP will let the user modify ANY environment variable!

	The  safe_mode_protected_env_vars  directive  contains a comma-delimited list of environment variables, that the end user won't be able to
       change using putenv(3). These variables will be protected even if safe_mode_allowed_env_vars is set to allow to change them.

PARAMETERS
	      o $setting
		- The setting, like "FOO=BAR"

RETURN VALUES
	Returns TRUE on success or FALSE on failure.

EXAMPLES
       Example #1

	      Setting an environment variable

	      <?php
	      putenv("UNIQID=$uniqid");
	      ?>

NOTES
       Warning

	       The safe_mode_allowed_env_vars and safe_mode_protected_env_vars directives only take effect when safe_mode is enabled.

SEE ALSO
       getenv(3).

PHP Documentation Group 														 PUTENV(3)