Lab Exercise: User and Group Management

1. Add a User with useradd Command:

   • We'll create a new user named "johndoe" using the useradd command:

     sudo useradd johndoe

   • This command will add an entry for "johndoe" in the /etc/passwd file.

2. Check the Entries in Files:

   • Verify the entries in the following files:

     • /etc/passwd: Contains user account information.

     • /etc/shadow: Contains encrypted passwords and other user-specific settings.

     • /etc/group: Contains group information.

   • You can use commands like cat, grep, or less to view the contents of these files.

3. Add User with Common Options:

   • Let's create a new user named "alice" with specific options:

     sudo useradd -g developers -G admins -s /bin/bash -d /home/alice -u 1001 alice

   • This command:

     • Sets the primary group to "developers."

     • Adds "alice" to the "admins" group.

     • Sets the login shell to /bin/bash.

     • Specifies the home directory as /home/alice.

     • Assigns a custom user ID (UID) of 1001.

4. Check Shadow Entry Before and After Password:

   • Before setting a password for "alice," check the /etc/shadow entry for her.

   • Set a password for "alice" using the passwd command:

     sudo passwd alice

   • After setting the password, verify the updated /etc/shadow entry.

5. Verify Home Directory and /etc/skel:

   • Check the contents of "alice"'s home directory (/home/alice).

   • Also, explore the contents of the /etc/skel directory, which serves as a template for new user home directories.

6. Use usermod to Change Group and Login Shell:

   • Change "alice"'s primary group to "devteam":

     sudo usermod -g devteam alice

   • Change her login shell to /bin/zsh:

     sudo usermod -s /bin/zsh alice

7. Create a New Group and Add It to an Existing User as a Secondary Group:

   • Create a new group named "designers":

     sudo groupadd designers

   • Add "alice" to the "designers" group:

     sudo usermod -a -G designers alice

8. Remove the User:

   • To remove "alice" and her home directory:

     sudo userdel -r alice

9. Use finger Command:

   • The finger command provides information about users. For example:

     finger alice

10. Lab Exercise:

    • Here's a lab exercise for you:

      • Create a new user named "bob."

      • Set his password.

      • Verify the entries in /etc/passwd, /etc/shadow, and /etc/group.

      • Explore Bob's home directory.

      • Change Bob's primary group to "developers."

      • Add him to the "designers" group.

      • Remove Bob from the system.