php man page for posix_setegid

POSIX_SETEGID(3)							 1							  POSIX_SETEGID(3)

posix_setegid - Set the effective GID of the current process

SYNOPSIS
       bool posix_setegid (int	$gid)

DESCRIPTION
	Set  the  effective  group ID of the current process. This is a privileged function and needs appropriate privileges (usually root) on the
       system to be able to perform this function.

PARAMETERS
	      o $gid
		- The group id.

RETURN VALUES
	Returns TRUE on success or FALSE on failure.

EXAMPLES
       Example #1

	      posix_setegid(3) example

	       This example will print out the effective group id, once changed.

	      <?php
	      echo 'My real group id is '.posix_getgid(); //20
	      posix_setegid(40);
	      echo 'My real group id is '.posix_getgid(); //20
	      echo 'My effective group id is '.posix_getegid(); //40
	      ?>

SEE ALSO
       posix_getgrgid(3), posix_getgid(3), posix_setgid(3).

PHP Documentation Group 													  POSIX_SETEGID(3)