Linux which groups exist

How to list all groups a user is a member of

Before delving into the 5 ways, let’s first understand some basics:

Adding a user to an existing group is one of the typical tasks of a Linux administrator.

A group is a collection of users. The main purpose of the group is to define a set of privileges to their members within the group.

It can be a difficult task if you want to assign a set of privileges to multiple users without a group. This is where the group comes in handy.

All system users are listed in the /etc/passwd file, the groups are listed in the /etc/group file, and the actual password is stored in the /etc/shadow file.

No matter what command we use, it will fetch information from these files.

There are two types of groups in Linux:

What is primary group?

The primary group is the main group associated with the user account. Each user must be a member of a single primary group.

What is secondary group?

The secondary or supplementary group is used to grant additional rights to the user. Each user can become a member of multiple secondary groups.

What is /etc/passwd file

“/etc/passwd” is a text file containing every user information that is required to login to the Linux system. It maintains useful information about users such as username, password, user ID, group ID, user information, home directory and shell.

Each user profile in the password file is a single line with seven fields as shown below:

$ grep "daygeek" /etc/passwd daygeek:x:1000:1000:daygeek. /home/daygeek:/bin/bash

What is /etc/group file

“/etc/group” is a text file that defines which groups a user belongs to. We can add multiple users in the same group.

Linux has three permission levels which define how users can access it. These levels are user, group and others, which controls a users access to other users’ files and folders.

/etc/group file maintains useful information about the group such as group name, group password, group ID (GIT) and membership list. Each group details is shown in a single line with four fields as shown in the ‘method #5’ listed below.

The following seven commands will help you find out which groups a user belongs to in Linux.

• groups: Show All Members of a Group.
• id: Print user and group information for the specified username.
• lid or libuser-lid: It display user’s groups or group’s users.
• getent: Get entries from Name Service Switch libraries.
• compgen: compgen is bash built-in command and it will show all available commands for the user.
• members: List members of a group.
• /etc/group file: Also, we can grep the corresponding user’s groups from the /etc/group file.

Now let’s delve into the 5 methods which can be used to find the list of groups a user is part of in Linux:

Method-1: Using groups command

The ‘groups’ command is widely used by Linux admin to list all groups a user is a member of. It prints the information of the given user’s primary and supplementary groups as shown below:

$ groups daygeek daygeek : daygeek adm cdrom sudo dip plugdev lpadmin sambashare

Run ‘groups’ command without any arguments to display the list of groups associated with the current user as shown below:

$ groups daygeek adm cdrom sudo dip plugdev lpadmin sambashare

Method-2: Using id command

The id command stands for identity. It prints real and effective user, group, and supplementary group information such as username, UID, group names and GUID as shown below:

$ id daygeek uid=1000(daygeek) gid=1000(daygeek) groups=1000(daygeek),4(adm),24(cdrom),27(sudo),30(dip),46(plugdev),118(lpadmin),128(sambashare)

Just run the ‘id’ command to view group information about the current user as shown below:

$ id uid=1000(daygeek) gid=1000(daygeek) groups=1000(daygeek),4(adm),24(cdrom),27(sudo),30(dip),46(plugdev),118(lpadmin),128(sambashare)

Method-3: Using lid command

The lid or libuser-lid command displays information about groups containing user name, which requires sudo privileges.

You should run the libuser-lid command instead of the lid on newer systems.

$ sudo libuser-lid daygeek adm(gid=4) cdrom(gid=24) sudo(gid=27) dip(gid=30) plugdev(gid=46) lpadmin(gid=116) daygeek(gid=1000) sambashare(gid=126)

Method-4: Using the getent command

The getent command displays entries from databases supported by the Name Service Switch libraries, which are configured in ‘/etc/nsswitch.conf’:

$ getent group | grep daygeek adm:x:4:syslog,daygeek cdrom:x:24:daygeek sudo:x:27:daygeek,2gadmin dip:x:30:daygeek plugdev:x:46:daygeek lpadmin:x:116:daygeek daygeek:x:1000: sambashare:x:126:daygeek

The above command shows the group name and all other members associated with that group. Use the below customized command format to print only groups for a given user:

$ getent group | grep daygeek | awk -F: '' adm cdrom sudo dip plugdev lpadmin daygeek sambashare

Run the below command to print only the primary group information of the user:

$ getent group daygeek daygeek:x:1000:

Method-5: Using the ‘/etc/group’ file

User groups information can be filtered from the ‘/etc/group’ file using grep command as shown below:

$ grep daygeek /etc/group adm:x:4:syslog,daygeek cdrom:x:24:daygeek sudo:x:27:daygeek,2gadmin dip:x:30:daygeek plugdev:x:46:daygeek lpadmin:x:116:daygeek daygeek:x:1000: sambashare:x:126:daygeek

Use the below customized command format to print only groups for a given user:

$ grep daygeek /etc/group | awk -F: '' adm cdrom sudo dip plugdev lpadmin daygeek sambashare

Bonus Tip-1: Find out all groups using compgen command

Compgen is a bash built-in command that displays all groups in the Linux system:

$ compgen -g root daemon bin sys adm . . daygeek thanu renu sudha admin u1 u2

Bonus Tip-2: Listing members of a group using member command

The member command allows you to list members of a group in Linux:

$ members sudo daygeek 2gadmin

Closing Notes

In this guide, we have shown you several commands to list all groups a user is a member of in Linux.

If you have any questions or feedback, feel free to comment below.

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How to Easily Find Which Groups a User Belongs to in Linux

Learn how to manage users and groups in Linux and determine access to devices and files using command line options like id, getent, and groups.

• Using the “id” command to print user and group information
• Using the “getent” command to list all members of a group
• Using the “groups” command to display the groups a user is in on Ubuntu Linux
• Understanding the /etc/group and /etc/passwd files
• Managing users and groups in Linux
• Other code samples for finding which groups a user belongs to in Linux
• Conclusion
• How do you list what groups a user is in Linux?
• How do I see existing groups in Linux?
• How do I find out what group a user is in Unix?
• Which command displays the list of groups to which a user belongs?

As a Linux user, it’s essential to know which groups a user belongs to determine their access to files and devices on the system. Linux provides several command-line options to find out which groups a user belongs to. In this article, we’ll take a look at some of the most commonly used methods to find out which groups a user belongs to in Linux.

Using the “id” command to print user and group information

The “id” command is a simple and easy-to-use command-line tool that displays the user and group information for the specified username. It can display both the real and effective user and group IDs. To use the “id” command, simply type the following command in the terminal:

Where [username] is the name of the user you want to find the groups for. For example, if you want to find the groups for the user “john,” you would type:

This will display the user ID, group ID, and all the groups that the user “john” belongs to in the following format:

uid=1000(john) gid=1000(john) groups=1000(john),4(adm),24(cdrom),27(sudo),30(dip),46(plugdev),119(lpadmin),120(lxd),131(sambashare) 

Using the “getent” command to list all members of a group

The “getent” command can be used to list all members of a group. To use the “getent” command, simply type the following command in the terminal:

Where [groupname] is the name of the group you want to list the members for. For example, if you want to list all the members of the “sudo” group, you would type:

This will display the group ID and all the members of the “sudo” group in the following format:

Using the “groups” command to display the groups a user is in on Ubuntu Linux

The “groups” command is another simple and easy-to-use command-line tool that can be used to display the groups a user is in on Ubuntu Linux. To use the “groups” command, simply type the following command in the terminal:

Where [username] is the name of the user you want to find the groups for. For example, if you want to find the groups for the user “john,” you would type:

This will display all the groups that the user “john” belongs to in the following format:

john : john adm cdrom sudo dip plugdev lpadmin lxd sambashare 

Understanding the /etc/group and /etc/passwd files

The group information is contained in the file /etc/group . The /etc/passwd file contains user account information, including the account name, home directory location, and default shell. The /etc/group file can be sliced with the cut command to display user and group information. The “passwd” command can be used to list primary groups. To display user and group information using the /etc/group file, type the following command in the terminal:

This will display the list of groups and their corresponding group IDs in the following format:

root:0 daemon:1 bin:2 sys:3 adm:4 tty:5 disk:6 lp:7 mail:8 news:9 uucp:10 man:12 proxy:13 kmem:15 dialout:20 fax:21 voice:22 cdrom:24 floppy:25 tape:26 sudo:27 audio:29 dip:30 www-data:33 backup:34 operator:37 list:38 irc:39 src:40 gnats:41 shadow:42 utmp:43 video:44 sasl:45 plugdev:46 staff:50 games:60 users:100 nogroup:65534 libuuid:101 netdev:102 crontab:103 syslog:104 messagebus:105 ttygrp:106 mlocate:107 ssh:108 lpadmin:119 lxd:120 sambashare:131 

Managing users and groups in Linux

In Linux, the groupadd, groupdel, and groupmod commands are used to add, delete, and modify groups, respectively. The root user or superuser is the most important user on a Linux system. Fedora uses a user private group (UPG) scheme, which makes UNIX groups. To add a new group, type the following command in the terminal:

Where [groupname] is the name of the group you want to add. For example:

To delete a group, type the following command in the terminal:

Where [groupname] is the name of the group you want to delete. For example:

To modify a group, use the groupmod command followed by the options and the group name. For example, to rename a group, type the following command in the terminal:

groupmod -n newname oldname 

Where newname is the new name of the group, and oldname is the old name of the group.

Other code samples for finding which groups a user belongs to in Linux

In Shell , for example, see what groups a user is in linux code sample

# this will display what groups the active user is in groups

In Shell as proof, linux list user groups code example

In Shell , in particular, linux user groups code example

Conclusion

In conclusion, Linux provides several command-line options for finding out which groups a user belongs to. Understanding the /etc/group and /etc/passwd files is important for managing users and groups in linux . Adding, deleting, and modifying groups can be useful for managing user access and permissions in Linux. By using the simple and easy-to-use command-line tools and commands mentioned in this article, you can easily find out which groups a user belongs to and manage users and groups in linux .

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