Change user and group ID on Linux

If you're using NFS mounts, user IDs should be synchronized across all servers. This is typically done via LDAP or NIS, but you can do it via manually managed gids and uids as well.

This is all great... if you remember.

If you forget when you're adding a new user, you can still fix it:

usermod -u UID USERNAME

groupmod -g NEWGID OLDGID

On RHEL, you may need to use /usr/sbin/usermod and /usr/sbin/groupmod