Lesson 2.4

Getting Help

5 minutes

One of the best things about Linux commands is that they come with built-in documentation. You never need to memorize every flag for every command — you just need to know how to look them up.

man — The Manual Pages

What it does: Opens the full manual page for any command.

Try it now: Type man ls

You’ll see a detailed page explaining everything ls can do — every flag, every option, with examples. Manual pages are organized into sections:

  • NAME — the command name and a short description
  • SYNOPSIS — how to use it (the syntax)
  • DESCRIPTION — what it does in detail
  • OPTIONS — every available flag explained

When you’re inside a man page:

Key Action
Space or Page Down Scroll down one page
b or Page Up Scroll up one page
/ then type a word Search for a word
n Jump to next search result
q Quit and return to the terminal

Try it now: Type man grep — browse the manual, then press q to exit.

man Pages vs. AI
Yes, you can ask an AI tool "what does ls -t do?" But knowing how to read man pages makes you self-sufficient. When you're on a server with no internet, or when you want to verify what an AI told you, man is always there.

–help — The Quick Reference

What it does: Shows a shorter, more concise help message.

Try it now: Type ls --help

Instead of a full manual page, you get a compact summary of all the available flags. This is faster than man when you just need to look up one flag.

Most commands support --help. Some also accept -h as a shortcut for help (though be careful — for ls, -h means “human-readable sizes,” not help).

which — Find Where a Command Lives

What it does: Shows you the full path to a command’s executable file.

Try it now: Type which ls

You’ll see something like /usr/bin/ls — that’s where the ls program actually lives on disk.

Try it: Type which cat and which mkdir to see where those commands are located.

Why which Is Useful

  • Checking if a command is installed: If which node returns nothing, Node.js isn’t installed
  • Finding which version you’re running: When you have multiple versions of a tool installed, which tells you which one your terminal is using
  • Debugging path issues: If a command isn’t working, which helps you figure out if the right version is being found
Three Ways to Get Help
man command — full manual (most detail)
command --help — quick reference (concise)
which command — where the command lives on disk

Between these three and your AI assistant, you can figure out any command.

Practice

Try looking up help for commands you’ve already learned:

  1. man cat — read the manual, then press q to quit
  2. mkdir --help — see the quick reference for mkdir
  3. which cat — find where cat lives on the system
BlueBox Terminal