Infrastructure & Operations › Linux & Servers

Basic Shell Commands

ls, cd, cp, mv, rm, cat, less and find.

Also known as: shell commands, terminal commands, ls cd cp mv rm, command line basics, bash commands

A handful of commands cover most of what you’ll do in a terminal.

Moving around

pwd                    # print the working directory (where am I?)
ls                     # list files        ls -l: details      ls -a: include hidden (.dotfiles)
cd projects/app        # change directory   cd ..: up one level   cd: go home   cd -: previous directory

Paths can be absolute (start at /: /home/ana/app) or relative to where you are (./app, ../other). ~ means your home directory.

Working with files

mkdir -p a/b/c         # create directories (-p: make parents too)
touch notes.txt        # create an empty file (or update its timestamp)
cp a.txt b.txt         # copy               cp -r dir1 dir2: copy a directory
mv a.txt docs/         # move or rename     mv old.txt new.txt
rm file.txt            # delete a file      rm -r dir: delete a directory and its contents

rm does not use a trash can. Deleted means gone. Be extra careful with rm -rf (recursive and forced) and with wildcards. A stray space (rm -rf / tmp) or a variable that turned out empty (rm -rf "$DIR"/*) can delete far more than you meant. Run ls with the same pattern first to see what matches.

Reading files

cat file.txt           # print the whole file
less file.txt          # page through it (q to quit, / to search)
head -n 20 file.txt    # first 20 lines
tail -n 50 app.log     # last 50 lines      tail -f app.log: follow as it grows

Finding things

find . -name "*.py"            # files by name, recursively
grep -rn "TODO" src/           # text inside files (see grep/ripgrep)
which python                   # where is this command?

Habits that save time

• Tab completion: press Tab to finish names. It also prevents typos.
• Up arrow / Ctrl+R to bring back and search previous commands.
• man ls or ls --help for documentation (man pages).
• Ctrl+C stops a running command. Ctrl+L clears the screen.
• Quote paths that contain spaces.
• Combine commands with pipes, ls | wc -l (pipes and redirection).

Flags differ slightly between Linux, macOS and other systems, so check the manual if something behaves differently from a tutorial.