Setting and changing user and group IDs (UID/GID)

System Administration Guide
Chapter 1, Administering user accounts

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.

WARNING: Within a network environment, each user and group must have a unique identification number across the entire network, rather than just on the home machine. For more information, see ``Establishing user equivalence'' in the Networking Guide and Chapter 9, ``Configuring the Network Information Service (NIS)'' in the Networking Guide.

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.

NOTE: When operating under the High security profile, a UID cannot be changed. Under other profiles, UIDs can be changed without restriction.