To find a user's UID or GID in Unix, use the id command.

To find a specific user's UID, at the Unix prompt, enter:

id -u username

Replace username with the appropriate user's username.

To find a user's GID, at the Unix prompt, enter:

id -g username

If you wish to find out all the groups a user belongs to, instead enter:

id -G username

If you wish to see the UID and all groups associated with a user, enter id
without any options, as follows:

id username