Set the effective group ID of the current process. This is a privileged function and you need appropriate privileges (usually root) on your system to be able to perform this function.
Example 1. posix_setegid() example
This example will print out your effective group id, once you change it.
|posix_getgrgid() for information on how to a group id into a useable group name|
|posix_getgid() get real group id.|
|posix_setgid() change the effective group id|