Git & Terminal Cheatsheet

Terminal Basics

Use this Git & Terminal reference while you build software engineering projects, review code for technical interview prep, or polish examples for a software engineer resume.

Orientation

pwd                 # print working directory (the absolute path you are in)
ls                  # list files
ls -la              # long listing, including hidden dotfiles
ls -lah             # same, with human-readable sizes (-h needs -l)
ls -lt              # newest files first
whoami              # current user
echo $SHELL         # your login shell (zsh, bash, ...)
uname -a            # OS and kernel info
clear               # clear the screen (or ctrl+l)

Getting Help

man ls              # full manual page (q to quit, / to search, n for next match)
ls --help           # built-in usage summary (GNU/Linux tools)
git --help          # same idea, works per subcommand: git commit --help
help cd             # help for a shell BUILT-IN (cd, export, alias, ...)
man -k copy         # search man pages by keyword (same as apropos)
type ls             # is it a builtin, alias, function, or binary?
which python3       # path of the binary that will run
tldr tar            # community example-first pages (brew/apt install tldr)

On macOS/BSD, ls --help does not exist, use man ls. And -h is never a help flag on classic Unix tools, for ls/du/df it means human-readable sizes.

Path Shortcuts

Symbol	Meaning
`~`	your home directory
`.`	the current directory
`..`	the parent directory (one level up)
`-`	the previous directory (`cd -` jumps back)
`/`	the filesystem root
`*`	glob: matches any characters (`*.log`)
`$VAR`	environment variable expansion (`$HOME`, `$PATH`)

Keyboard Shortcuts

Keys	Action
`ctrl+c`	interrupt (stop) the running command
`ctrl+d`	end of input / close the shell
`ctrl+l`	clear the screen
`ctrl+r`	reverse-search command history (press again for older)
`ctrl+a` / `ctrl+e`	jump to start / end of line
`ctrl+w`	delete the word before the cursor
`ctrl+u` / `ctrl+k`	delete to start / end of line
`tab`	autocomplete paths and commands
`↑` / `↓`	walk command history
`!!`	re-run the previous command (`sudo !!`)

Reading and Opening Files

cat notes.txt           # print a whole file
less app.log            # page through a big file (q quits, /text searches, G = end)
head -n 20 app.log      # first 20 lines
tail -n 20 app.log      # last 20 lines
tail -f app.log         # follow a file as it grows (live logs), ctrl+c stops
wc -l app.log           # count lines
open .                  # macOS: open the current folder in Finder
open file.pdf           # macOS: open in the default app
xdg-open .              # Linux desktop equivalent of open

Pipes and Redirection

ps aux | grep node          # pipe: output of one command into another
history | tail -20          # last 20 commands you ran
ls > files.txt              # redirect stdout to a file (overwrite)
ls >> files.txt             # append instead of overwrite
npm run build 2> errors.log # redirect stderr only
npm run build > all.log 2>&1   # stdout AND stderr to one file
sort < names.txt            # read stdin from a file
ls *.txt | xargs wc -l      # feed piped output as ARGUMENTS to a command
make 2>&1 | tee build.log   # show output AND save it to a file

Operator	Meaning
`a \| b`	stdout of `a` becomes stdin of `b`
`>` / `>>`	write / append stdout to a file
`2>`	redirect stderr
`2>&1`	merge stderr into stdout
`&&`	run next command only if the previous succeeded
`\|\|`	run next command only if the previous failed