ID(1) General Commands Manual ID(1)

id — return user identity

id [user]

id -A

id -F [user]

id -G [-n] [user]

id -P [user]

id -g [-nr] [user]

id -p [user]

id -u [-nr] [user]

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.

The options are as follows:

Display the process audit user ID and other process audit properties, which requires privilege.
Display the full name of the user.
Display the different group IDs (effective, real and supplementary) as white-space separated numbers, in no particular order.
Display the id as a password file entry.
Ignored for compatibility with other id implementations.
Display the effective group ID as a number.
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.
Make the output human-readable. If the user name returned by getlogin(2) is different from the login name referenced by the user ID, the name returned by getlogin(2) is displayed, preceded by the keyword “login”. The user ID as a name is displayed, preceded by the keyword “uid”. If the effective user ID is different from the real user ID, the real user ID is displayed as a name, preceded by the keyword “euid”. If the effective group ID is different from the real group ID, the real group ID is displayed as a name, preceded by the keyword “rgid”. The list of groups to which the user belongs is then displayed as names, preceded by the keyword “groups”. Each display is on a separate line.
Display the real ID for the -g and -u options instead of the effective ID.
Display the effective user ID as a number.

The id utility exits 0 on success, and >0 if an error occurs.

Show information for the user ‘bob’ as a password file entry:

$ id -P bob
bob:*:0:0::0:0:Robert:/bob:/usr/local/bin/bash

Same output as groups(1) for the root user:

$ id -Gn root
wheel operator

Show human readable information about ‘alice’:

$ id -p alice
uid     alice
groups  alice webcamd vboxusers

Assuming the user ‘bob’ executed “su -l” to simulate a root login, compare the result of the following commands:

# id -un
root
# who am i
bob          pts/5        Dec  4 19:51

groups(1), who(1)

The id function is expected to conform to IEEE Std 1003.2 (“POSIX.2”).

The historic groups(1) command is equivalent to “id -Gn [user]”.

The historic whoami(1) command is equivalent to “id -un”.

The id command appeared in 4.4BSD.

March 5, 2011 macOS 15.2