Check all group linux

How to List All Existing Groups in Linux System

Being able to manage users and groups in a Linux operating system environment is an important milestone in terms of Linux administration and security. Under Linux, each user account is automatically associated with a single primary group. A Linux user cannot be a member of two or more primary groups, only one.

However, when it comes to secondary groups, it’s a different case. A single Linux user account can be associated with more than one secondary group (up to 15).

In summary, a primary group is OS-assigned to each Linux user account and is linked to user-created files whereas secondary groups can be associated with multiple Linux user accounts and are not always automatically assigned.

This article will walk us through viable approaches to listing all existing groups within a Linux operating system distribution.

1. Reading the /etc/group File

By default, all defined groups in Linux are listed inside the /etc/group file. The entries in this file are represented in the following format:

group_name:password:GID:group_members

All the password entries are encrypted and GID stands for Group ID.

The entries in the /etc/group file are in plain text making it easier to output its content via a simple cat command.

We can therefore list all groups stored inside the /etc/group file in the following manner:

The above command outputs all groups present in a Linux system as the first column entry followed by the password, GID, and group_members fields if any.

What if we only wanted to output the group_name field? To achieve this objective, we will implement and use the cut command to only extract and output the group_name field from the /etc/group file entries.

• -d tells the cut command to use field delimiters as TABs replacement.
• -f1 tells the cut command to print the content of the first field (field 1) inside the /etc/group file.

2. Using getent Command

As per its manual page, the getent command is effective in accessing Name Service Switch libraries’ entries. The entries in the /etc/group file are supported by databases easily read by the getent command.

The getent command’s reference syntax is as follows:

$ getent [option]. database key.

In our case, its implementation in listing all groups in Linux is straightforward and simple as depicted below:

The first entry in each line represents the group names.

Listing All Groups of a Specific User in Linux

We can now comfortably identify and audit the existence of all groups in our Linux OS environment. What if we wanted to list all groups associated with a particular Linux user?

For the currently logged-in user, all you need to do is execute the following single command:

If you want to audit the groups assigned to other Linux users on the system, reference the following syntax:

For example, we can implement the above command syntax in the following manner:

Have any other ideas on listing all groups in Linux? Feel free to leave a comment or feedback.

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How to List All User Groups on Linux

Get better at user management by learning more about the existing user groups on your Linux computer.

Readers like you help support MUO. When you make a purchase using links on our site, we may earn an affiliate commission. Read More.

User groups on Linux help you define a set of permissions that you can then impose on other users. Unix and Linux come with some pre-configured user groups, and as an administrator, it’s easy to create additional groups to further categorize and manage users.

But before creating a new group, you’d want to know more about the existing ones. Luckily, there are several ways to list all user groups present on Linux, and you can even view the list of groups a specific user is a part of. Let’s get started.

Using the /etc/group File

The /etc/group file contains information on all local user groups configured on a Linux machine. With the /etc/group file, you can view group names, passwords, group IDs, and members associated with each group.

View the contents of the file using the cat command:

The output might be confusing at first. Where are the group names? And what are these «x»s and colons in the output?

The first column (the text before the first colon) is what you’re looking for. You can view a prettified version of the file and display only the group names using the cut command:

This simple list is both easier on the eyes and perfect for use in scripts.

You can also count the total number of local groups on your machine using wc:

To make things interesting, create a new group using the groupadd command and then view the total number of user groups on your system. As obvious, the count will increase by one and you’ll be able to see the group name listed in the output.

List Groups Using the getent Command

getent, short for «get entries,» is a Linux command for viewing the contents of system information files, also known as databases, on Linux. /etc/group, /etc/passwd, and /etc/shadow files are good examples of such databases.

Using the getent command to view user group information on Linux is straightforward. All you need to do is type getent followed by the file you want to view. In this case, it’s the group file.

The output of «getent group» will be slightly different from the cat /etc/group command. This is because getent pulls group information from other similar databases on your system (LDAP, for example).

Use the cut command to parse the output and display only group names:

The getent command is versatile. You can list the names of all users on Linux by getting all the entries from the /etc/passwd file and then parsing the output for user names.

View Group List for a Specific User Using groups

It’s hard to visually match user names with their groups using the previous methods. If you only want to list groups a particular user is a part of, consider using the groups command instead.

The basic syntax for the command is:

If you don’t specify a username, the output will display all groups for the current user. But for the sake of clarity, it’s best to supply a username as an argument.

To get a list of groups for a user named «testuser», run:

Groups Simplify User Access Control on Linux

Technically, the root user is the owner of the entire system and has permissions no other user possesses. Groups are a way for the superuser to categorize users, grant them authorizations, and impose restrictions to prevent them from performing undesirable operations.

Instead of granting permissions to each user, you can create a group and add all the users to it. Then, all you need to do is manage the permissions for the said group and the rules will be imposed upon the members automatically. This is one of the many ways to manage users on Linux and other Unix-related operating systems.

Deepesh has a degree in Computer Applications and has been writing about technology since 2018. When not penning down informational guides on Linux, Windows, or Gaming, you can find him secluded in a corner reading books, playing FPS games, or searching for new hobbies to take up, only to quit and find a new one again.

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How to List All Groups in Linux?

Linux groups are a collection of users. They are meant to easily provide privileges to a group of users. In this tutorial, we will look at various ways to list all groups in Linux.

2 Ways to List All Groups in Linux

1. /etc/group file

The /etc/group file contains all the local groups. So, we can open this file and look at all the groups.

root@localhost:~# cat /etc/group root:x:0: daemon:x:1: bin:x:2: sys:x:3: adm:x:4:syslog tty:x:5: disk:x:6: lp:x:7: mail:x:8: news:x:9: .

If you are looking for a specific group, then use the grep command to filter it out.

root@localhost:~# cat /etc/group | grep sudo sudo:x:27:journaldev,test root@localhost:~#

2. getent command

Linux getent command fetch entries from databases supported by the Name Service Switch libraries. We can use it to get all the groups information from the group database.

root@localhost:~# getent group root:x:0: daemon:x:1: bin:x:2: sys:x:3: adm:x:4:syslog tty:x:5: .

Let’s look at some more examples of listing all the groups in Linux.

Linux List All Group Names

We can use cut command to print only the group names. This is useful when we are looking for a specific group name presence in a shell script.

root@localhost:~# cut -d: -f1 /etc/group root daemon bin sys adm tty .

We can use cut command with the getent command too.

root@localhost:~# getent group | cut -d: -f1 root daemon bin sys adm tty disk .

The cut command is splitting every line using the colon (:) delimiter. Then the first field, which is the group name, is selected using the -f1 option.

Listing All Group Names in Alphabetical Order

The above commands output can be passed to the sort command to print the output in natural sorting order.

root@localhost:~# getent group | cut -d: -f1 | sort adm audio backup bin cdrom crontab daemon .

Count of All the Linux Groups

If you are interested in the count of the linux groups, use the following commands.

root@localhost:~# cat /etc/group | grep -c "" 68 root@localhost:~# getent group | grep -c "" 68 root@localhost:~#

List All Groups of a User

We can use the groups command to get all the groups of a user.

root@localhost:~# groups journaldev journaldev : journaldev sudo test_users test_users_pwd root@localhost:~# root@localhost:~# groups root root : root root@localhost:~#

List Groups of the Current User

If you run the groups command without any user input, it will print the groups of the current user.

root@localhost:~# groups root root@localhost:~# su - journaldev journaldev@localhost:~$ groups journaldev sudo test_users test_users_pwd journaldev@localhost:~$

List User Groups Along with Group ID

We can use id command to print the user information. This command lists all the groups along with their group id.

root@localhost:~# id journaldev uid=1002(journaldev) gid=1003(journaldev) groups=1003(journaldev),27(sudo),1004(test_users),1007(test_users_pwd) root@localhost:~# root@localhost:~# id root uid=0(root) gid=0(root) groups=0(root) root@localhost:~#

List All Users of a Group

We can use the getent command or the /etc/groups file to get all the users that belongs to a group.

root@localhost:~# getent group sudo sudo:x:27:journaldev,test root@localhost:~# root@localhost:~# getent group sudo | cut -d: -f4 journaldev,test root@localhost:~#

Conclusion

The getent command and /etc/group file can be used to get all the Linux groups details. We can use them alongside cut and sort command to present the output in a better way.

References

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