In this tutorial, we will show you how to use the id command in Linux and other Unix-based systems.
One of the most useful commands is Linux is the
id command. This command allows you to find the user ID, or
UID and group ID or
GUID of a specific username in the Linux system.
Knowing the IDs of a user can help you diagnose problems and find processes access various resources in the system. We can also use the IDs to determine in which group a user belongs.
id Command Syntax
The command follows are relatively simple and straightforward syntax. Luckily, you can use the
id without any arguments.
id [OPTION] [USER]
The command accepts two main arguments as shown:
OPTION- specifies the command option to alter how the command behaves.
USER- specifies the username whose
GIDyou wish to determine. Luckily, you can specify a single or multiple usernames.
id Command Options
The following are the accepted command options:
-A Display the process audit user ID and other process audit properties, which requires privilege. -F Display the full name of the user. -G Display the different group IDs (effective, real and supplementary) as white-space separated numbers, in no particular order. -P Display the id as a password file entry. -a Ignored for compatibility with other id implementations. -g Display the effective group ID as a number. -n Display the name of the user or group ID for the -G, -g and -u options instead of the number. -p Make the output human-readable. -r Display the real ID for the -g and -u options instead of the effective ID. -u Display the effective user ID as a number. --version Display command version
Basic Command Usage
As stated, the
id command is easy to use. If you run the
id command without any arguments, it will display the information about the current user.
Running the command should return information as shown:
uid=1000(debian) gid=1000(debian) groups=1000(debian),24(cdrom),25(floppy),27(sudo),29(audio),30(dip),44(video),46(plugdev),109(netdev),113(scanner),116(lpadmin)
Among the displayed information includes the UID, GID and other supplementary information such as the group names.
Keep in mind that if the system has SELinux Enabled, it will display security context.
Get Group ID using the
The simplest way to fetch the group ID of specific user with the
id command is using the
An example is as shown:
Get All Groups using the
We can fetch all the groups attached to a specific user using the
1000 24 25 27 29 30 44 46 109 113 116
To show the group name instead of the ID, we can use the
-Gn option as:
debian cdrom floppy sudo audio dip video plugdev netdev scanner lpadmin
You can also use the
-gn to show the group of user.
Showing Real Group ID
By default, the
id command displays the effective ID instead of the real ID. To display the real ID, we can use the
Show User ID
We can print the effective User ID with the -u option:
You can show the usernames instead of the User ID with the
id -un 0
Show Security Context
We can also show the security context of a specific process using the -Z options.
id: --context (-Z) works only on an SELinux-enabled kernel
In this article, we learned how to use the
id command to get the user information about a given user such as the username, User ID and Group ID.
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