Linux groups Command: Show a User's Group Memberships

groups shows the names of the groups the current user or a specified user belongs to. It is used to quickly check shared file access permissions or membership in administrative groups.

What is the groups command?

When run without arguments, it prints the list of groups for the current process. If you specify a user, it retrieves the group information for that account. If you need the numeric GID or the distinction between primary and supplementary groups, id provides more detailed information.

Basic syntax

groups [user...]

Installed implementations and options may vary depending on the distribution. Check the description for your system with man groups.

Examples

Check groups in the current session

See if the groups assigned to an account are reflected in the current shell.

groups

Check a specific user

Check which groups the account you are managing belongs to.

groups alice

Compare with numeric ID

When investigating permission issues, check both the group name and ID together.

id alice

Linking Group List to Permissions

groups shows the group names of the current user or a specified user. The output format may vary depending on the implementation and whether arguments are used.

groups alice

Example output:

alice : alice sudo

Here, the first alice is the user being queried, and the list after the colon is the group list. Changes in group membership may not be reflected in sessions that are already running immediately after the change. Check the group IDs actually applied to the current process using id.

Main Options and Format

Precautions when using

Changes may not be reflected in existing login sessions immediately after a group is newly added. Check groups and id in the current session and log in again if necessary. Just seeing the group name does not mean you have access to all paths. Parent directory permissions and ACLs also affect access.

Frequently Asked Questions

Why are the results of groups alice and groups without arguments different?

The former may query the account database anew, while the latter shows the list of groups that the current process has.

Official Documentation

The exact behavior of options and implementation differences can be checked in the official documentation related to groups.