Skip to content
ohsudo, Home

Module 1: First steps

Help yourself: help, man, Tab and history

Nobody remembers every option. These are the habits that make the command line quick: asking the system itself, letting it finish your typing, and reusing what you've already run.

● Runs 100% in your browser. Nothing here can harm a real system.

Step 1 of 6

What can I run here?

In this playground, help lists every command it has. On a real system, help only covers shell built-ins, and man is what you'll use.

Your task

List the available commands.

guest@ohsudo: ~ — Ubuntu 24.04

Starting the terminal…

What you'll practice

  1. What can I run here?. In this playground, help lists every command it has. On a real system, help only covers shell built-ins, and man is what you'll use.
  2. Read the manual. man shows the manual of a command. On a real system, you scroll it as with less, and press q to leave. Search inside with /.
  3. Let Tab type for you. Press Tab while typing a name, and the shell finishes it. It also prevents typos. Press it twice to see the options if there's more than one.
  4. See what you ran. history lists your past commands. The up arrow brings back the last ones, one at a time, so you can run them again or change them.
  5. Who am I?. id shows your user and your groups. On Debian and Ubuntu, being in the sudo group is what lets you use sudo. id shows your user and your groups. On RHEL, Rocky and AlmaLinux, being in the wheel group is what lets you use sudo.
  6. Where is this command?. which shows the file that runs when you type a command. It helps when a command isn't found, or when the wrong version runs.

See also