How to Allow a User to Run Commands as Another User in Ubuntu

Managing user privileges is essential for system administration in Ubuntu. This article details the methods for permitting one user to execute commands under the identity of another. We will explore the standard switch user command, the sudo utility, and how to safely modify configuration files to grant persistent permissions.

Using the su Command

The su (switch user) command allows you to log in as another user directly. You must know the password of the target account. To switch to a user named “exampleuser” and load their environment variables, run:

su - exampleuser

To exit the session and return to your original user, type exit.

Using sudo to Execute Specific Commands

The sudo command allows authorized users to run specific commands as another user without switching the entire shell session. You will be prompted for your own password, not the target user’s password. The syntax is:

sudo -u exampleuser command

For example, to list the home directory contents as “exampleuser”:

sudo -u exampleuser ls /home/exampleuser

Configuring Permanent Sudoers Access

To allow a user to run commands as another user repeatedly without editing command lines manually, you must configure the sudoers file. Always use the visudo command to edit this file, as it checks for syntax errors before saving.

1. Open the sudoers file:

   sudo visudo

2. Add a rule granting permission. To allow “adminuser” to run commands as “exampleuser”, add this line:

   adminuser ALL=(exampleuser) ALL

3. Save and exit the editor.

Once configured, “adminuser” can run any command as “exampleuser” using the sudo -u exampleuser syntax described earlier.