(PHP 4, PHP 5)
posix_geteuid — Return the effective user ID of the current process
Return the numeric effective user ID of the current process. See also posix_getpwuid() for information on how to convert this into a useable username.
Returns the user id, as an integer
Example#1 posix_geteuid() example
This example will show the current user id then set the effective user id to a separate id using posix_seteuid(), then show the difference between the real id and the effective id.
<?php
echo posix_getuid()."\n"; //10001
echo posix_geteuid()."\n"; //10001
posix_seteuid(10000);
echo posix_getuid()."\n"; //10001
echo posix_geteuid()."\n"; //10000
?>