Bash Command Line Cheat Sheet

Most commands looks like this: ls -l code

The first part (ls) is the command. Different commands do different things.
The second part (-l) is an option. They change how the commands work.
The third part (code) is an argument. They specify what the command acts on.

Options are always optional. Some commands (and some options) have required arguments. In this cheat sheet, <argument> means that the argument is required; [argument] means that the argument is optional.

Getting Help

https://google.com/ - Google is your friend. Googling a command or a task will often give you multiple ways of doing what you need.
<command> --help - Calling the command with the --help option will often print out a short help message.
man <command> - Many commands have a manual you can read. It's on the verbose side and is not always easy to understand, but it's built into every system.
https://explainshell.com/ - If you see a command you want every option and argument explained, ExplainShell will match each part with its explanation from the man pages.

Stopping

exit - Log out of the command line.
ctrl+c - Most commands can be stopped by pressing CTRL+C. Note that it's still Control, not ⌘ or Option or Alt, on a Mac.
q - Some commands (notably man, less, and top) use the Q key to quit.

File Navigation

pwd - Print the present working directory (ie. the current folder) you are in.
cd [path] - Change directory to the given path. If no path is given, changes to your home directory.
ls [path] - List the contents of the given path, or the current directory if none is given. Common options include -a to show all files and -l to use the long format (ie. more details).

File Manipulation

mkdir <path> - Make a directory (the given path). Use -p to also create intermediate (prerequiste) directories as needed.
mv <file> <path> - Move a file to a directory.
cp <file> <path> - Copy a file to a directory.
rm <file> - Remove a file. This does not ask for confirmation and cannot be undone.
rmdir <path> - Remove a directory. Only works if the directory is already empty. This does not ask for confirmation and cannot be undone.
less <file> - Display a file. Press q to quit.

Text Manipulation

nano <file> - Edit a file. The available commands are listed at the bottom, with the ^ meaning CTRL (eg. CTRL+X to exit).
head <file> - Print the first 10 lines of a file. Use -n 20 to print (for example) the first 20 lines.
tail <file> - Print the last 10 lines of a file. Use -n 20 to print (for example) the last 20 lines.
wc <file> - Show a word count of a file.
sort <file> - Sort a file by lines. Use -i to ignore case and -n to treat the lines as numbers.
grep <text> <file> - Print the lines where <text> exists in <file>. Use -i to ignore case and -r to recursively search through directories.
uniq - Print the unique lines of a file. Assumes the file to be sorted first. Use -d to show duplicates instead and -c to count each unique line.

System Status

date - Print the current date.
uptime - Print how long the computer has been on.
top - Show the most active programs. Press q to quit.
df - Show the amount of space available on the hard disk. Use -h to get human-readable sizes.
du <file> - Show the amount of space taken up by the file. The current directory is used if no file is given. Use -h to get human-readable sizes, and -s to get separate sizes for each file.
uname- Print system information. Use -a to show all information.

Other Utilities

cal [[month] year] - Print a calendar, optionally specifying year and month.
diff <file1> <file2> - Find the difference between two files. Use -y to show the files side-by-side.

Advanced Topics

Pipes - Many commands can be chained together with the pipe (|), so the output of one becomes the input of the other. For example, head <file> | sort | uniq -c will count the unique items in the first ten lines of a file.
Command Substitution - In commands that have a text argument (eg. grep), the text could be the output of another command. For example, grep "$(head -n 1 <file1>)" <file2> will search file2 for the first line of file1.
Variables, Branches, Loops - Bash is a full programming language with variables, branches, and loops. Check the Advanced Bash Scripting Guide for more information.