posix_initgroups

PHP 5 >= 5.2.0, PHP 7, PHP 8
posix_initgroups - Calculate the group access list
Manual

posix_initgroups( string$username, int$group_id ): bool

Calculates the group access list for the user specified in name.

Parameters

username

The user to calculate the list for.

group_id

Typically the group number from the password file.

Return Values

Returns true on success or false on failure.