Command Line Study Guide

This is a guide for becoming more familiar with the command line. These are some basic GNU/Linux terminal commands that are useful to know as a minimum.

Built-in Documentation

Most commands come with documentation in the form of "man[ual] pages". To read the man page for a command use the man command.

Example: to read the documentation for the ls command, type man ls in a terminal. You can also search Google for information on any command.

If the man pages are too overwheming, there is also a simpler tool called tldr.

List of Useful Commands

Click on the name of a command for more information.


  • clear -- clear the terminal. Also ctrl-l


  • man -- read the built-in documentation
  • tldr -- shorter, simpler documentation for commands

Where Am I?

  • pwd -- show your current location in the filesystem
  • cd -- change directory
  • ls -- list directory contents. Also ls -l, ls -R, and ls -al.
  • tree -- list a directory as a tree. e.g., tree -d >> outputfile.txt. You may need to install it first.

An alternative way to move around and keep track of where you've been is to use dirs.

  • dirs -- a stack of recently visited directories
  • pushd -- move to another directory with a bookmark (actually a stack of directories you've jumped from, so you can use it multiple times)
  • popd -- jump back to the place where you pushd'd from

Manipulating Files

  • cp -- copy files
  • mv -- move a file or directory. Also for renaming things
  • mkdir -- make a directory
  • rm -- remove a file. Also rm -rf, but very dangerous. See this story for a warning on how dangerous it can be.
  • rmdir --- remove a directory
  • touch -- create a new empty file

Finding Files

  • grep -- search the contents of files
  • rg -- ripgrep
  • locate -- find files
  • find -- find files. E.g., find / -name '*.desktop'
  • fd -- a find command with some improvements


  • which -- tells you where a program is located
  • apropos -- can't remember a command? Use this to find commands about a keyword, like: apropos wireless


  • ping
  • dig
  • traceroute

Reading and Editing Files

  • less -- display output with pagination
  • vim -- type vimtutor and see the [[Vim]] page.
  • nano -- simple console editor
  • cat -- display a file and/or concatenate it.
  • bat -- like cat but with syntax highlighting and other improvements
  • tee -- redirect the output to a file and the screen at the same time. E.g., ls -1 *.py | wc -l | tee count.txt which counts the number of Python files in your directory, writes it to the screen, and saves it to a file.
  • wc -- count things: lines, bytes, characters, words, etc. Example: wc -l filename.txt will count the lines in a file.
  • head -- view the first lines of a file
  • tail -- view the last lines of a file
  • diff -- compare two different files

Users, Groups, and Permissions

  • chmod
  • chown

The System

  • top -- show processes. If you like that, install htop.
  • htop
  • du
  • df
  • kill
  • ps
  • shutdown
  • reboot
  • uptime
  • date
  • sleep

Compressing and Extracting Files

  • tar
  • zip
  • gzip

Other Tips

  • tab completion
  • pipes |, >, and >>
  • aliases
  • ctrl-r -- reverse search
  • keyboard shortcuts: ctrl-u, ctrl-k, ctrl-a, ctrl-e, alt-f, alt-v, ctrl-d, alt-d (from Emacs)

For managing remote servers: ssh, scp, and rsync

And Tmux.

Additional Utilities

Some of these may need to be installed.

  • sort -- sorts items
  • uniq -- gets only unique items
  • mc -- Midnight Commander file browser
  • tr -- translate
  • fold -- wrap lines to a specified width
  • jq -- tools for JSON
  • curl -- do stuff with URLs
  • wget -- download pages and sites
  • sql2csv (npm install -g sql2csv)
  • csvkit (pip install csvkit)
  • xml2json (git clone it and add to path)
  • ImageMagick -- process and view images, e.g., display cat_pic.jpg, convert --resize 200x200 giant_hubble_photo.jpg hubble_photo_thumb.jpg
  • rename -- bulk rename files with regular expressions. Example: rename all files with the extension .GIF to .gif: rename -v 's/\.GIF$/\.gif/' *.GIF
  • lynx -- a browser in your terminal.

You will occasionally come across these:

  • sed -- stream editor for filtering and transforming text
  • awk -- pattern scanning and processing language
  • Perl one line scripts

See additional tools that you might want to investigate:

How to use the terminal for everything:

tig can be used as an alternative to git log. ranger is a file browser.


See this post for useful keyboard shortcuts:

Additional Resources

See also 7 command line tools for data science.

See also GNU Coreutils Manual.

There are additional posts here: #command-line.