Linux Command-Line Cheat Sheet

Linux is one of the most widely used operating systems in the world, and with such a high level of usage, it has essentially become one of the most important tools for any IT professional to have. A lot of Linux’s power resides in the terminal emulator.

In this article, I will share a Linux command-line cheat sheet to help you get started with using Linux. The commands mentioned below will serve as the foundation for working across the different distributions and families of Linux, as there are many of them.

Get Started

I will start by explaining how the Linux terminal works. This is an oversimplified explanation to give you a basic understanding. The terminal is software that you use to communicate with the operating system. Anything you type into it is passed to a shell, which interprets the command and, when appropriate, executes the corresponding program.

For starters, one question that has plagued humanity for centuries: whoami.

whoami

After running this command, it will print your username, allowing you to know which user you are currently logged in as. It is also quite often used by attackers after they breach a system to determine which user they are operating as.

File Management

Let’s create a file. There are multiple ways to create a file, but one of the most common is the touch command. It is used to create an empty file or update the timestamps of an existing file.

If you want to create a file with some content, you can use the echo command. This command is used to print something to the screen, but you can redirect that output (hey, save this) to a file using >. For appending content, which means adding content to the end of an existing file, you can use >>.

Be careful, though: the single > symbol will overwrite the contents of a file if it already exists.

touch test.txt

echo "Konnichiwa, World" > test.txt

Now that you have created a file, you might want to delete it. For that, you can use the rm command. It can be used to delete both files and folders.

rm test.txt

Let’s make a folder. To create a folder, you can use the mkdir command. This command accepts the name of the folder you want to create and will create it for you.

mkdir mynicefolder

To delete the folder you just created, you can use the rmdir command. It is used to delete empty folders.

If you have multiple files inside the folder, you will need to use the previous command with a cute little flag. A flag is a special option that you use to modify how a command behaves, allowing it to perform additional functions, such as deleting a non-empty folder.

For this, you can use rm -r. The -r flag stands for recursive , which tells the command to delete the folder and everything inside it.

rmdir mynicefolder

rm -rf mynicefolder

There are two more useful commands you should know, the copy and move commands.

For copying files, you can use the cp command. It follows the syntax <file to copy> <location to copy to>.

cp test.txt /home/skipper

For moving files, you can use the mv command. It follows the same syntax as the cp command, but instead of creating a copy, it moves the file entirely to a new location.

mv test.txt /home/purpleshonen

Navigation

Before we learn to move across different directories or folders, we need to know which directory you are currently in, and for that, there is a very useful command called pwd. It stands for print working directory , and it will print the directory you are currently working in.

pwd

Linux filesystems follow a tree-like structure, and you can imagine it as an upside-down tree. You are moving towards or up the tree towards the root, and when you move to a different directory, for example /home/skipper, you are moving away and downward from the root. This will make more sense with the infographic below, and the root directory is / in Linux, unlike in Windows, where you typically have different drive letters such as C:\.

Before you can navigate around and change directories, you need to learn about the ls command, which is used for listing files and directories. If you don’t provide any <location>, it’s gonna print out the files and directories in the current directory.

ls

In order to move around, you use the cd command, which stands for change directory. In order to go back to the previous directory, you can use .., which acts somewhat like the back button in a file explorer and moves you one directory up. To change directory to another folder, you need to put the name of the directory you are trying to move into.

cd ..

cd mynicefolder

As I mentioned above, Linux has a tree-like hierarchy. It also has two types of paths, and each works to achieve the same goal but works differently. These two are absolute paths and relative paths. I will explain these in a little more detail.

An absolute path starts from the root. An example of it would be /home/skipper/test.txt; this is an absolute path.

A relative path starts from the current working directory. For example, if you are currently in /home/skipper, you can use ../purpleshonen/ to move to the purpleshonen directory under /home. This is considered a relative path because it is resolved based on your current working directory.

I hope that makes sense. It’s important to understand, as it is crucial when moving around to different directories or using any command that requires a path.

Now that you have a good understanding of how to navigate around, and if you want to go to your home directory from any directory, then you can use the ~ symbol, which represents your home directory.

cd ~/

Permissions

Linux uses discretionary access control (DAC) for its traditional file permission system, which means the owner of a file or folder can decide what permissions different users have, subject to the system’s permission rules. In Linux, to see the permissions of different files, you can use the -l flag with the ls command. It’s gonna show the permissions for the owner, then the permissions for the group, and lastly the permissions for others.

In order to change the permissions, we use the chmod command, which is short for change mode , aka changing permissions. In the example below, you will see how we can make a file or script executable by using the +x option and then the name of the filename.

chmod +x test.bin

To remove the execute permission, you can change the +x to -x. Now the file will no longer have the execute permission that was previously added.

chmod -x test.bin

There are multiple options you can use aside from the execute permission. For read permission, you can use the +r option, and for write permission, you can use +w. Being able to manipulate permissions is a very crucial part of the Linux system. You should familiarize yourself with chmod commands, as it’s a very useful yet powerful command.

Networking

Networking is also a very crucial part of Linux, and there are a few important commands you should be familiar with. Some of the important ones start with the ip command. This command is a very powerful utility that is used to manage networking, IP addresses, routing tables, and network interfaces.

To view the IP addresses configured on your system, you can use the address show argument to list and view them.

ip address show

If you specifically want to view IPv4 addresses, you can use:

ip -4 address show

In order to view the network interfaces available or check their state, you can use the link show argument, which will list and show all the available interfaces on your system.

ip link show

These were some of the common commands that would come in handy when using the Linux operating system, and below I will add a table of the most common commands used in everyday use that would be a valuable asset to learn.

Before I end this article, I have one last command.

If you don’t know what a specific command does or you want to learn more about any of the commands covered, then you can use the man <command name> command, which will open up a manual that you can read to further understand how to use that specific command and what other options it supports.

man <command>

Cheat Sheet

Below are some of the most useful Linux commands that you should familiarize yourself with. The commands covered above are intentionally left out, so this section can serve as a quick reference for commands that you haven’t seen yet.

Files & Directories

Command	What it does	Example
cat	Displays the contents of a file	cat test.txt
less	Lets you read a file one screen at a time	less test.txt
head	Displays the beginning of a file	head test.txt
tail	Displays the end of a file	tail test.txt
file	Determines the type of a file	file test.txt
find	Searches for files and directories	find /home -name "test.txt"
locate	Quickly searches for files by name	locate test.txt
tree	Displays directories in a tree structure	tree /home
ln	Creates links to files	ln -s /path/to/file link
stat	Displays detailed file information	stat test.txt

Text Processing

Command	What it does	Example
grep	Searches for text inside files or command output	grep "password" file.txt
sort	Sorts lines of text	sort names.txt
uniq	Removes or identifies repeated lines	uniq names.txt
cut	Extracts sections from lines of text	cut -d: -f1 /etc/passwd
wc	Counts lines, words, and characters	wc -l file.txt
tr	Translates or removes characters	tr 'a-z' 'A-Z'
sed	Searches and transforms text	sed 's/foo/bar/g' file.txt
awk	Processes and analyzes structured text	awk '{print $1}' file.txt
diff	Compares two files	diff file1.txt file2.txt

Processes & System

Command	What it does	Example
ps	Displays running processes	ps aux
top	Displays running processes and system activity	top
htop	Interactive process viewer	htop
kill	Sends a signal to a process	kill 1234
pkill	Sends a signal to processes by name	pkill firefox
jobs	Shows jobs running in the current shell	jobs
bg	Sends a stopped job to the background	bg
fg	Brings a background job to the foreground	fg
free	Displays memory usage	free -h
df	Displays filesystem disk usage	df -h
du	Displays the size of files and directories	du -sh /home
uptime	Shows how long the system has been running	uptime
uname	Displays system information	uname -a
hostname	Displays or changes the system hostname	hostname
lsblk	Lists block devices and storage drives	lsblk
mount	Mounts a filesystem	mount /dev/sdb1 /mnt
umount	Unmounts a filesystem	umount /mnt

Networking

Command	What it does	Example
ping	Tests network connectivity	ping 8.8.8.8
ss	Displays network sockets and connections	ss -tuln
curl	Transfers data from or to a URL	curl https://example.com
wget	Downloads files from the web	wget https://example.com/file.zip
dig	Performs DNS lookups	dig example.com
nslookup	Performs DNS queries	nslookup example.com
traceroute	Shows the route packets take to a destination	traceroute example.com
hostnamectl	Displays or manages hostname information	hostnamectl
arp	Displays or modifies ARP information	arp -a

Users & Permissions

Command	What it does	Example
id	Displays user and group information	id
groups	Shows the groups a user belongs to	groups
sudo	Executes a command with elevated privileges	sudo command
su	Switches to another user	su username
passwd	Changes a user’s password	passwd
chown	Changes the owner of a file	sudo chown user file.txt
chgrp	Changes the group ownership of a file	sudo chgrp developers file.txt
umask	Displays or changes the default permission mask	umask

Archives & Compression

Command	What it does	Example
tar	Creates or extracts archives	tar -cf archive.tar files/
gzip	Compresses files using gzip	gzip file.txt
gunzip	Decompresses gzip files	gunzip file.txt.gz
zip	Creates ZIP archives	zip archive.zip file.txt
unzip	Extracts ZIP archives	unzip archive.zip

Package Management

Package management commands depend on the Linux distribution you are using.

Command	What it does	Example
apt	Manages packages on Debian-based distributions	sudo apt install nmap
dnf	Manages packages on Fedora-based distributions	sudo dnf install nmap
pacman	Manages packages on Arch-based distributions	sudo pacman -S nmap
rpm	Works with RPM packages	rpm -qa
dpkg	Works with Debian packages	dpkg -l

Services & Logs

Command	What it does	Example
systemctl	Manages systemd services	systemctl status sshd
journalctl	Reads systemd logs	journalctl -u sshd
dmesg	Displays kernel messages	dmesg
service	Manages services on systems that support it	service ssh status

Shell & Environment

Command	What it does	Example
clear	Clears the terminal	clear
history	Displays previously executed commands	history
alias	Creates command shortcuts	alias ll='ls -la'
env	Displays environment variables	env
printenv	Prints environment variables	printenv HOME
export	Sets an environment variable	export NAME=value
which	Shows the location of a command	which python
whereis	Locates binaries, source files, and manuals	whereis python
type	Shows how the shell interprets a command	type cd
echo $PATH	Displays the command search path	echo $PATH

Useful Shortcuts

Shortcut	What it does
Ctrl + C	Stops the currently running command
Ctrl + D	Exits the current shell or sends EOF
Ctrl + L	Clears the terminal screen
Ctrl + Z	Suspends the current process
Ctrl + R	Searches through command history
Tab	Autocompletes commands, paths, and filenames
↑ / ↓	Moves through command history
!!	Repeats the previous command
&&	Runs the next command only if the previous command succeeds
|	Pipes the output of one command into another
>	Redirects output and overwrites a file
>>	Redirects output and appends to a file
2>	Redirects standard error
2>&1	Redirects standard error to standard output

This is by no means an exhaustive list of Linux commands. Linux has thousands of commands and utilities, and many of them are designed for very specific tasks. However, learning these commands will give you a much stronger foundation for working with the Linux command line.