# Linux commands: su

> Learn how the Linux su command switches your shell to another user, starting a new shell, or to root when run alone, with exit to return to your own user.

Author: [Flavio Copes](https://flaviocopes.com/about/) | Published: 2020-09-20 | Topics: [CLI](https://flaviocopes.com/tags/cli/) | Canonical: https://flaviocopes.com/linux-command-su/

While you're logged in to the terminal shell with one user, you might have the need to switch to another user.

For example you're logged in as root to perform some maintenance, but then you want to switch to a user account.

You can do so with the `su` command:

```bash
su <username>
```

For example: `su flavio`.

If you're logged in as a user, running `su` without anything else will prompt to enter the `root` user password, as that's the default behavior.

![Terminal window showing su command prompting for password after running su without arguments](https://flaviocopes.com/images/linux-command-su/Screen_Shot_2020-09-03_at_18.18.09.png)

`su` will start a new shell as another user.

When you're done, typing `exit` in the shell will close that shell, and will return back to the current user's shell.

> The `su` command works on Linux. On macOS it will not work unless you enable the root user (tip: you can use `sudo` instead)