8 Different Use Cases for the `doas` Command (with examples)

Run a command as root

Code: doas command

Motivation: Sometimes, certain commands require root privileges to run properly. By using doas, you can easily execute commands as the superuser.

Explanation: The doas command allows you to execute a specific command with root privileges. Simply replace command with the command you intend to run as root.

Example usage: doas apt-get update

Example output: The system will update the package lists as it would when the command is run with sudo.

Run a command as another user

Code: doas -u user command

Motivation: In some cases, you may need to execute a command as a different user to perform specific tasks that require their permissions, such as accessing files or starting applications.

Explanation: By using the -u flag followed by the desired username, you can execute a command as that user. Replace user with the desired username and command with the command you want to run.

Example usage: doas -u bob touch /home/bob/test.txt

Example output: The file test.txt will be created in Bob’s home directory.

Launch the default shell as root

Code: doas -s

Motivation: Launching a default shell as root can be handy when you need to perform multiple administrative tasks without repeatedly using doas.

Explanation: The -s flag allows you to launch the default shell as root, providing you with a shell with elevated privileges.

Example usage: doas -s

Example output: An interactive shell with root privileges will be launched.

Parse a config file and check if the execution of a command as another user is allowed

Code: doas -C config_file command

Motivation: Parsing a config file helps verify if the execution of a command as another user is permitted, which aids in managing security and access control.

Explanation: By using the -C flag followed by the path to the config file and command, you can check if the execution of the command as another user is allowed according to the configuration file.

Example usage: doas -C /etc/doas.conf touch /root/test.txt

Example output: The command will only execute if the doas.conf file allows “touch” to be run as another user.

Make doas request a password even after it was supplied earlier

Code: doas -L

Motivation: In certain scenarios, you may want to enforce reauthentication before executing a command, even if a password was entered earlier.

Explanation: The -L flag causes doas to request the user’s password even if authentication succeeded earlier. This can be useful when a certain time has passed since the initial authentication, adding an extra layer of security.

Example usage: doas -L apt-get install package

Example output: The system will prompt for password input, even if the user has previously entered a password for authentication.