Creating User Groups Automatically with Useradd Command

The useradd command in Unix-like operating systems is used to create new user accounts. One of the options available with this command is -U or --user-group. This option instructs useradd to create a new group with the same name as the user, and add the user to this group by default. This is particularly useful for ensuring that each user has their own dedicated group without the need for manual group creation.

Here are several examples demonstrating the usage of useradd with the -U option:

Example 1: Creating a user ‘john’ and automatically creating a group ‘john’.

    $ sudo useradd -U john
    

Output: No output indicates success. To verify, check the existence of user ‘john’ and group ‘john’.

Example 2: Creating a user ‘alice’ and automatically creating a group ‘alice’.

    $ sudo useradd -U alice
    

Output: No output on success. Verify by checking user ‘alice’ and group ‘alice’.

Example 3: Creating a user ‘mark’ with the --user-group option.

    $ sudo useradd --user-group mark
    

Output: No output if successful. Check user ‘mark’ and group ‘mark’ for verification.

Example 4: Specifying additional options while using -U, such as setting a home directory.

    $ sudo useradd -U -d /home/sam sam
    

Output: No output upon success. Verify the user ‘sam’ and group ‘sam’ existence.

Example 5: Creating a user ‘testuser’ with a specified UID and automatically creating group ‘testuser’.

    $ sudo useradd -U -u 2001 testuser
    

Output: No output if successful. Verify the presence of ‘testuser’ and its corresponding group.

Example 6: Creating a user ‘demo’ with -U and specifying a different shell.

    $ sudo useradd -U -s /bin/bash demo
    

Output: No output if user ‘demo’ and group ‘demo’ are created successfully. Verify both ‘demo’ user and group.

Example 7: Creating a user ‘backup’ with -U and specifying supplementary groups.

    $ sudo useradd -U -G adm,users backup
    

Output: No output upon success. Verify user ‘backup’ and its supplementary groups ‘adm’ and ‘users’.

Example 8: Creating a user ‘newuser’ with -U and specifying a comment.

    $ sudo useradd -U -c "New User Account" newuser
    

Output: No output if the command executes successfully. Verify user ‘newuser’ and its corresponding group.

Example 9: Creating a user ‘dev’ with -U and specifying an expiration date.

    $ sudo useradd -U -e 2025-12-31 dev
    

Output: No output if successful. Verify the presence of ‘dev’ user and ‘dev’ group before the expiration date.

Example 10: Creating a user ‘webadmin’ with -U and setting a password expiry date.

    $ sudo useradd -U -f 30 webadmin
    

Output: No output upon success. Verify user ‘webadmin’ and ‘webadmin’ group for the changes.