id

id [OPTION]... [USER]...

Print user and group information for each specified USER, or (when USER omitted) for the current user.

Options

-A

Display the process audit user ID and other process audit properties,
which requires privilege (not available on Linux).

--user, -u

Display only the effective user ID as a number.

--group, -g

Display only the effective group ID as a number

--groups, -G

Display only the different group IDs as white-space separated numbers, in no particular order.

-p

Make the output human-readable. Each display is on a separate line.

--name, -n

Display the name of the user or group ID for the -G, -g and -u options instead of the number.
If any of the ID numbers cannot be mapped into names, the number will be displayed as usual.

-P

Display the id as a password file entry.

--real, -r

Display the real ID for the -G, -g and -u options instead of the effective ID.

--zero, -z

delimit entries with NUL characters, not whitespace;
not permitted in default format

--context, -Z

print only the security context of the process

The id utility displays the user and group names and numeric IDs, of the calling process, to the standard output. If the real and effective IDs are different, both are displayed, otherwise only the real ID is displayed.

If a user (login name or user ID) is specified, the user and group IDs of that user are displayed. In this case, the real and effective IDs are assumed to be the same.

Examples

Display current user's ID (UID), group ID (GID) and groups to which they belong:

id

Display the current user identity:

id -un

Display the current user identity as a number:

id -u

Display the current primary group identity:

id -gn

Display the current primary group identity as a number:

id -g

Display an arbitrary user's ID (UID), group ID (GID) and groups to which they belong:

id {{username}}

The examples are provided by the tldr-pages project under the CC BY 4.0 License.

Please note that, as uutils is a work in progress, some examples might fail.