Each user and group is assigned an identification number (UID or GID). This ID number is stamped on all files, directories, and processes on local and NFS-mounted filesystems. When you create a new user or group, a new UID or GID number is automatically assigned, but you can specify another by entering it in the text field.
To change the ID number for an existing user or group, use the usermod(ADM) or groupmod(ADM) command. Changing an ID number of a user or group does not change the ID on files owned by the user or group; the system administrator must do this manually as described in ``Changing ownership of files with an obsolete UID/GID''.
To alter the range of UIDs from which you select for new users, select User Defaults from the Options menu. To alter the range of GIDs from which you select for new groups, Group Defaults from the Options menu.
If you have changed or removed a UID or GID, you must change the ownership of their files and check your filesystems for orphaned files. Files without a real owner have a number in the owner and/or group name fields:
-rw-r--r-- 1 obie pub 68476 Nov 16 12:06 accts.s -rw-r--r-- 1 15625 pub 508 Oct 31 11:15 balance -rw-r--r-- 1 obie pub 40596 Aug 31 13:19 report.2In this example, the file balance is an orphaned file. The number appears because files are stamped with the ID number rather than the user or group name.
utility to locate and change the ownership of files.
This command line finds all files on the system owned by user
UID and changes ownership to user newowner:
find / -user UID -print | xargs -t chown newowner
This variation changes the group ownership:
find / -user GID -print | xargs -t chgrp newgroup
Instead of changing the ownership, you can perform other actions, such as archiving the files; see ``Locating files''.