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How to Create a new group in Linux | groupadd command

Last Updated : 15 Sep, 2024

In the Linux operating system, user management is a crucial aspect of system administration. One of the fundamental tasks is creating and managing user groups. Groups in Linux allow administrators to organize and control user access to various resources and files. The groupadd command is a powerful tool that facilitates the creation of new groups effortlessly. In this article, we will delve into the details of using the groupadd command to create a new group in Linux.

Groups in Linux refer to the user groups. In Linux, there can be many users of a single system, (a normal user can take uid from 1000 to 60000, and one root user (uid 0) and 999 system users (uid 1 to 999)). In a scenario where there are many users, there might be some privileges that some users have and some don't, and it becomes difficult to manage all the permissions at the individual user level. So, using groups, we can group together a number of users, and set privileges and permissions for the entire group. 

Before we dive into the practical aspects, let's briefly understand the concept of user groups in Linux. A group is a collection of users with similar permissions or access levels. Groups make it easier to manage and assign permissions to multiple users at once, enhancing security and simplifying administrative tasks.

The `groupadd` command follows a simple syntax:

groupadd [options] group_name

Here,

• 'group_name': This is the name of the group you want to create.
• '[options]': These are various flags that allow customization of the group creation process, such as specifying a Group ID (GID), setting a password, or creating system groups.

Follow these steps to create a new group in Linux using the groupadd command:

Launch a terminal on your Linux system. This can usually be done by pressing `Ctrl + Alt + T` or searching for "Terminal" in the application menu.

To create a new group, type the following command in the terminal:

Example:  

If we want to create a group named "developers", we can use the following command.

sudo groupadd developers 

Replace "mygroup" with the desired name for your new group. The sudo command is used to execute the groupadd command with administrative privileges.

Every new group created is registered in the file "/etc/group". To verify that the group has been created, enter the command. 

sudo tail /etc/group

The file shows group information in the following format:  

group_name : password : group-id : list-of-members

The 'groupadd' command provides several options to customize the group creation process. Here are some of the most commonly used options:

• This option forces the command to silently abort if the group with the given name already exists.
• If used with the -g or --gid option and the specified group id already exists, the command forcefully ignores the given group id and assigns a new and unique group id.

• This option assigns a specific numeric group id to the newly created group.
• The group id (GID) should be non-negative and unique, unless explicitly created to be non-unique using the -o or --non-unique option.
• If not specified, the command assigns a default group id greater than any existing group id.

• Displays a help message, providing information about the groupadd command and its available options.
• Useful for quickly accessing command documentation.

• Overrides the default values set in the /etc/login.defs file.
• Multiple -K options can be specified.
• Parameters like GID_MIN and GID_MAX, defined in /etc/login.defs, can be modified using this option.

• Permits adding a group with a non-unique group id (GID).
• Useful when you want to create groups with duplicate GIDs.

• Sets an encrypted password for the group.
• The password, returned by crypt(3), is visible to users and is stored in the /etc/gshadow file.
• By default, the password is disabled, and it is crucial to ensure it adheres to the system's password policy.

• Creates a system group.
• System groups have numeric identifiers chosen within the SYS_GID_MIN-SYS_GID_MAX range, as defined in the /etc/login.defs file, instead of GID_MIN and GID_MAX.

• Applies changes in the specified CHROOT_DIR directory and uses the configuration files from that directory.
• Useful when managing groups within a chroot environment.

Syntax:

groupadd -f developers

If we want to assign a specific group id to the newly created group, use the '-g' option. 

Syntax:

sudo groupadd -g 1001 developers

This command will create a new group named "developer" with a GID of 1001. Specifying group ID is useful in case where we need to maintain consistency across systems.

We can set an encrypted password for a group using the '-p' option.

Syntax:

sudo groupadd -p somepassword finance

This command creates a new group named "finance" and sets the password for the group as "somepassword"

Suppose we want to modify the 'GID_MIN' and 'GID_MAX' values for a group creation. We can achieve this using the '-K' option

Syntax:

 groupadd -K GID_MIN=500 -K GID_MAX=700 tester

This command will create a new group named "tester" and set the minimum GID to 500 and the maximum GID to 700. This allows us to have finer control over the range of valid group IDs for the created group.

Syntax:

sudo useradd -g developers new_user 

Syntax:

usermod -g developers existing_user  

In this article we have discussed `groupadd` command. By understanding and utilizing the options we have discussed in the 'groupadd' command, we can effectively manage group IDs, create system groups, set group passwords, and customize default value according to our specific requirements and security policies.

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