In operating systems, applications add their own users and groups to the system. From an administrative point of view, this makes it easier for users. Adding users to the application group is the easiest way to edit privileges. As a matter of fact, systems such as LDAP and Active Directory are also built on this method.
There are many methods of listing groups in Linux. In some methods, group information is accessed from the user, while in some methods, users are accessed from group information. We will tell you some of the most used methods with examples.
Method-1: Using groups command
When you run the groups command without any parameters, it lists the group information of the user who opened the terminal:
foc@fedora:~$ groups
foc wheel
If you type a username after the group command, the groups belonging to that user are listed:
foc@fedora:~$ groups golinux
golinux : golinux
In this method, groups are listed with user information.
Method-2: Using id command
Like the group command, the id command, when executed without parameters, lists the active user's groups. But this time group id are also displayed:
foc@fedora:~$ id
uid=1000(foc) gid=1000(foc) groups=1000(foc),10(wheel)
By typing the username after the id command, the groups belonging to that user are listed with their ids:
foc@fedora:~$ id golinux
uid=1001(golinux) gid=1001(golinux) groups=1001(golinux)
As the user's group information increases, the information displayed on the screen may not be understood. With the parameters of the ID command, the output can be made more understandable. For example, to list all group ids and names:
foc@fedora:~$ id -Gn golinux
golinux
You can get help from the --help page for all its parameters:
foc@fedora:~$ id --help Usage: id [OPTION]... [USER]... Print user and group information for each specified USER, or (when USER omitted) for the current user. -a ignore, for compatibility with other versions -Z, --context print only the security context of the process -g, --group print only the effective group ID -G, --groups print all group IDs -n, --name print a name instead of a number, for -ugG -r, --real print the real ID instead of the effective ID, with -ugG -u, --user print only the effective user ID
Again in this method, groups are listed with their user information.
Method-3: Using getent command
The getent command pulls information from the group database. If there is no central system such as LDAP, Active Directory, it will pull from the local database.
You can pull groups by typing group after getent command:
foc@fedora:~$ getent group root:x:0: bin:x:1: ... disk:x:6: lp:x:7: mem:x:8: kmem:x:9: wheel:x:10:foc cdrom:x:11: mail:x:12:
To list users in a group, you must type the group name:
foc@fedora:~$ getent group wheel
wheel:x:10:foc
To list all groups in the system without details:
foc@fedora:~$ getent group | cut -d: -f1
root
bin
disk
lp
mem
kmem
wheel
cdrom
mail
This method lists both groups and users in that group.
Method-4: Using /etc/group file
On Linux the group information is in the /etc/group file. If a user is added or removed from the group, this file changes.
When you view this file with file view commands like cat , it gives a complex output. To list group information, you can write it like this:
foc@fedora:~$ cut -d: -f1 /etc/group
root
bin
...
lp
mem
kmem
wheel
...
tape
video
ftp
For the total number of groups:
foc@fedora:~$ cat /etc/group | grep -c ""
82
Using awk command we can extract the group names from the /etc/group file using the colon (:) delimiter.
awk -F: '{ print $1 }' /etc/group
Method-5: Using compgen command
Another command you can use to list groups in Linux is compgen. You can list the groups in the system with the -g parameter:
[foc@rocky9 ~]$ compgen -g
root
bin
wheel
ftp
lock
audio
users
nobody
foc
Method-6: Using lid command
This command displays information about the specified group, including the GID, group password (if any), and members.
# lid -g nagios
nagios(uid=1001)
apache(uid=48)
snmptt(uid=974)
Method-7: Using dscl command (On MacOS)
Using the dscl command on macOS. This command displays information about the specified group on macOS.
dscl . -read /Groups/groupname
Bonus Tip
If you want to list the groups of users logged into the system, you can use the following for loop:
[foc@rocky9 ~]$ for user in $(cat /etc/passwd | grep bash | awk -F: '{print $1}');do groups $user; done
root : root
foc : foc wheel
Note: Bash was chosen as the default shell. If a different shell(zsh,sh etc) is used, it can be written after the grep command.
What is NEXT?
- 10 practical examples to add or remove user from group in Linux
- How to add user to sudo group in Ubuntu [SOLVED]
- 15 usermod command examples in Linux [Cheat Sheet]
- Learn Linux wheel group usage [With Examples]
Summary
There is always an alternative on Linux. We have explained different ways to list groups in Linux for you. The commands and methods used may vary according to habits. You can use whichever method is faster and easier for you. Of course the choice is yours.
You can get help with the -h/--help parameter for each command. For more detailed information, you can also access the man page of the commands as in the example:
foc@fedora:~$ man id
NAME
id - print real and effective user and group IDs
SYNOPSIS
id [OPTION]... [USER]...
...
References
unix.stackexchange.com - How to list groups with gid in redhat?
stackoverflow.com - Is there a command to list all Unix group names?
