posix_setgid

(PHP 4, PHP 5, PHP 7, PHP 8)

posix_setgid — Set the GID of the current process

Description

posix_setgid(int $group_id): bool

Set the real 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 appropriate order of function calls is posix_setgid() first, posix_setuid() last.

Note:
If the caller is a super user, this will also set the effective group id.

Parameters

group_id: The group id.

Return Values

Returns true on success or false on failure.

Examples

Example #1 posix_setgid() example

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

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

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User Contributed Notes 1 note

down

jac ¶

13 years ago

if you're going to use this along with posix_setuid, make sure you call posix_setgid first:



<?php

define (PROC_USER, 'john');

define (PROC_GRP, 'admins');

?>



following works:



<?php

$user = posix_getpwnam( PROC_USER );

$group = posix_getgrnam( PROC_GRP);



echo posix_getuid()."\n";

echo posix_getgid()."\n";



posix_setgid($group['gid']);

posix_setuid($user['uid']);



echo posix_getuid()."\n";

echo posix_getgid()."\n";

?>



following will not set gid



<?php

$user = posix_getpwnam( PROC_USER );

$group = posix_getgrnam( PROC_GRP);



echo posix_getuid()."\n";

echo posix_getgid()."\n";



posix_setuid($user['uid']);

posix_setgid($group['gid']);



echo posix_getuid()."\n";

echo posix_getgid()."\n";

?>