Lecture # 17 - User Management

Creating a new User:

There are two commands that can add a user.

• useradd:

  useradd is a low level utility. This command is written as sudo useradd [options] [user-name] .

• 

  adduser:

  adduser is a high level utility. This command is written as sudo adduser [options] [user-name] .

  

Deleting a User:

There are two commands to delete a user.

• userdel:

  userdel is a low level utility. This command is written as sudo deluser [options] [user-name] .

  

  By using this command the directory of the user will not be deleted.

• 

  Delete the user and also its directory:

  To delete the user and its directory in one command sudo userdel --remove [user-name] is used.

• 

  deluser:

  deluser is a high level utility. This command is written as sudo deluser [options] [user-name] .

  

Set a password for a user:

To set a password for a user sudo passwd [user-name] is used.

Create a Service Account:

To create a service account sudo useradd --system [service-name] is used.

Change the username of a user:

To change the username of a user account sudo usermod --login [new-name] [old-name] is used.

Change the shell for a user:

To change the shell for a user sudo usermod --shell /bin/bash [user-name] is used. When you make a user account sh shell is set by default for the user.

Switch User:

To switch the user sudo su [user-name-to-be-switched] is used. By entering exit command you can exit from the new user and move back to the main user.

Lock/Disable User:

• usermod:

  To lock or disable a user account using usermod sudo usermod -L [user-name] is used.

• 

  passwd:

  To lock or disable a user account using passwd sudo passwd -l [user-name] is used.

  

Unlock/Enable User:

• usermod:

  To unlock or enable a user account using usermod sudo usermod -U [user-name] is used.

• 

  passwd:

  To unlock or enable a user account using passwd sudo passwd -u [user-name] is used.