(PHP 4 >= 4.0.2, PHP 5)
posix_setegid — Set the effective GID of the current process
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.
The group id.
如果成功则返回 TRUE，失败则返回 FALSE。
Example#1 posix_setegid() 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
?>