Rocky Linux Core Commands: Page 7

This page covers commands for managing users and groups on your Rocky Linux system.

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31. useradd - Create a New User Account

Purpose: The useradd command is used to create a new user account on the system. It creates an entry in the system account files and optionally creates a home directory and copies skeleton files.

Syntax: sudo useradd [OPTIONS] USERNAME

Key Options:

• -m: (create home directory) Creates the user's home directory if it doesn't exist.
• -s SHELL: Specifies the user's login shell (e.g., /bin/bash, /bin/sh).
• -g GROUP: Specifies the primary group for the new user.
• -G GROUP1,GROUP2: Adds the user to supplementary groups.
• -c "COMMENT": Adds a comment for the user (e.g., full name).

Examples:

sudo useradd -m newuser
sudo useradd -m -s /bin/bash -c "John Doe" johndoe
sudo useradd -m -g developers -G sudo,webdev jane

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32. passwd - Change User Password

Purpose: The passwd command is used to change a user's password. Users can change their own password, while the root user can change any user's password.

Syntax: passwd [OPTIONS] [USERNAME]

Examples:

passwd             # Change your own password
sudo passwd root   # Change the root user's password
sudo passwd newuser # Set or change password for 'newuser'

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33. usermod - Modify a User Account

Purpose: The usermod command is used to modify an existing user account. You can change a user's home directory, shell, group memberships, and more.

Syntax: sudo usermod [OPTIONS] USERNAME

Key Options:

• -l NEW_LOGIN: Change the user's login name.
• -d HOME_DIR: Change the user's home directory.
• -m: (move home directory) Moves the content of the current home directory to the new location. Used with -d.
• -s SHELL: Change the user's login shell.
• -aG GROUP: Add the user to a supplementary group (-a appends, -G specifies groups).

Examples:

sudo usermod -l newname oldname
sudo usermod -d /home/newhome -m username
sudo usermod -s /bin/zsh myuser
sudo usermod -aG admin,developers alice

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34. userdel - Delete a User Account

Purpose: The userdel command is used to delete a user account from the system.

Syntax: sudo userdel [OPTIONS] USERNAME

Key Options:

• -r: (remove home directory) Removes the user's home directory and mail spool along with the account.

Examples:

sudo userdel olduser
sudo userdel -r unusedaccount

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35. groupadd - Create a New Group

Purpose: The groupadd command is used to create a new group on the system.

Syntax: sudo groupadd [OPTIONS] GROUPNAME

Examples:

sudo groupadd developers
sudo groupadd web_admins