UNIX Cheatsheet

This document is NOWHERE NEAR COMPREHENSIVE. To learn more, visit Dr. Spielman’s website and see “Resources” –> “Command Line”!

Directory

• A folder on your computer which contains files. UNIX filesystems are organized as hierarchical directories.
• Forward slashes divide levels in the nested hierarchy of directories, e.g. /top_level_directory/second_level_directory
• The directory at the top of this hierarchy is called the root directory and is denoted simply as /.

Path

• The address to a directory or file on your computer. There are, generally, two types of paths:
  • Absolute/full path represents the path of a given directory/file beginning at the root directory.
  • Relative path represents the path of a given directory/file relative to the working/current directory.

Fundamental UNIX commands

Note that # are used for comments UNIX, just like in R (and python!)

Command	Description	Usage
pwd	Display the path of the current directory (aka print working directory)	pwd # yup that's it!
ls	List files and directories in current directory.	ls # yup that's it! ls -l # display long ls -a # show hidden files ls -la # display long and show hidden files
cd	Change directory	cd path/to/where/I/want/to/go # Go one directory BACK cd .. # one directory back. We move backwards with ..
cp	Copy a file or directory (use cp -r). The original file is NOT changed, like “copy and paste” (cmd+C/cmd+V)	Make a copy of oldfile.txt called newfile.txt cp oldfile.txt newfile.txt # Make a copy of the directory first_directory to be called second_directory cp -r first_directory second_directory
mv	Move or rename a file or directory. The original file is changed, like “cut and paste” (cmd+X/cmd+V)	# RENAME file from oldfile.txt to newfile.txt mv oldfile.txt newfile.txt # MOVE oldfile.txt to live in the directory into_this_directory/ cp oldfile.txt into_this_directory/ # MOVE oldfile.txt to live one directory back cp oldfile.txt ..
touch	Create an new (empty) file.	touch name-of-the-new-file-you-want-to-make.txt
mkdir	Create a new directory/folder (aka make directory)	# Create a new folder called new_directory mkdir new_directory
rm	Remove a file or directory (use rm -r). This is PERMANENT!!!	# PERMANENTLY delete a file rm file_I_dont_need.txt # PERMANENTLY delete a folder rm -r directory_I_dont_need/
clear	Clear screen (can still simply scroll up for past commands! they aren’t gone!).	clear # yup that's it!
history	View history of recent past commands	history # yup that's it!

Shortcuts and symbols

Shortcut/symbol	Description
Ctrl+C	Kills current process/command. USE THIS WHEN THINGS GET WEIRD!
tab (tab key)	autocomplete word
↑ (up arrow)	scroll back through previous commands
.	Represent the current directory you are in.
..	Represents one directory backwards. For example, the path ../.. means: two directories back.