id

Additional Notes

id prints identity information for a user: UID, primary GID, and supplementary groups.

It is useful for checking permission problems, group membership, container identity, and service accounts.

Syntax

id [options] [user]

Parameters

• options: Flags that change how id behaves.
• user: User account affected by the command.
• group: Group account affected by the command.
• file: File or directory whose ownership, mode, or access policy is being changed.

Common Options

• -u: Print only the user ID.
• -g: Print only the primary group ID.
• -G: Print all group IDs.
• -n: Print names instead of numbers when used with -u, -g, or -G.
• -r: Print real ID instead of effective ID.

Examples

id

Show your UID, GID, and groups.

id rani

Show identity information for user rani.

id -u

Print only your UID.

id -nG

Print group names for your user.

id www-data

Inspect a service account.

Practical Notes

• UID 0 is root.
• Group membership affects file and device access.
• After adding a user to a group, the user may need to log out and back in.
• Use groups for a simpler group-only view.