45 Essential Linux Commands (with Examples)

man — Show help (the manual)

Linux has a manual which you can read offline (yes, I know, retro!)

man lets you read the manual (sometimes called manpages or the system reference manuals).

Each command in Linux has its own page (or screen) in man.

When you want to call up the documentation for a particular command, just type man then the command name.

# Show the manual page for the `ls` command.
$ man ls

# Search for 'search'
$ man -k search

which — Find out where a command is

If a command exists on your system, which tell you!

which tells you where a command is located on your disk. That’s called the path to the command.

Alternatively, if you want to look for files, try locate.

# Shows the location of the command `ls` (all Linux systems have this!)
$ which ls

<command> --help — Find help on any command

Shows quick help on any command. It will show you the arguments, parameters that a command takes, so you can use the command in the correct way.

(Most commands recognise --help, but you might find a few commands which don’t, or prefer -h instead.)

# Show quick help for the command `ls`
$ ls --help

Ctrl+C — Stop the current program

This key combination will terminate the current command and return you to the command prompt.

It actually sends a shutdown signal to the command, so you can sometimes expect the command to do a little tidying-up first before it exits.

:q! — Quit the vi text editor without saving

vi (the text editor) is one of the commands where Ctrl+C to exit doesn’t work. So if you’re planning to use vi (and you should, it’s a life-enriching experience!), remember this key combination! This sequence of keys will let you quit the editor, without saving your changes.

Honestly I still have this command on a sticky note next to my laptop. :)

logout — Exit the current login shell

Quit your current terminal session and return back to where you came from. If you’re connected to a remote server, then it logout should return you back to your local terminal.

You can also usually use the keyboard shortcut Ctrl+D to logout.

passwd — Change your password

It’s important to change your password once in a while! Always choose a secure password, or a passphrase, which is several words joined together.

(If you want help choosing a secure password, try this free tool from Bitwarden.)

# Change your password (you'll be prompted for your current password first)
$ passwd

sudo — Execute a command as a superuser

When you want to do something that only superusers can do, use this command. For example, editing a system file or running a powerful command.

This can sometimes be a bit difficult to understand for beginners, so if you want to dive deeper into this then check out this blog from Red Hat.

# Edit the file `/etc/motd` (which only superusers have write access to)
$ sudo vi /etc/motd

ssh — Create an SSH connection (a terminal) to a server

When you connect to another server, you usually use SSH to do it.

This command creates a new session and then prompts you to log in.

# Opens an SSH connection to _example.com_ and tries to log in as user _dave_.
$ ssh dave@example.com

cd — Change the current directory (folder)

To move between different folders, use cd.

# Change directory to `mydocs`
$ cd mydocs

# Change to the parent directory (the directory above the current one)
$ cd ..

# Change to your user home directory (note it's just `cd` without any arguments!)
$ cd

ls — List files in a directory

List files and directories. You can add different options to the command, to change the output or sort it.

This is the closest equivalent to the dir command on Windows.

# List files in the current directory (to show your current directory, type [pwd](#pwd))
$ ls

# List files (including hidden files) and also show their permissions and who owns them.
$ ls -al

# List files (including hidden), ordering by most recent at the bottom.
$ ls -alrt

mkdir — Make/create a new directory

Directories work just like folders. Use this command to create a new one.

# Make a directory called `songs`
$ mkdir songs

pwd — Print current directory

This shows the your working directory (also called the current directory).

cp — Copy files and directories

This command lets you create a copy of a file or a directory and its contents. It’s mega-useful for creating backups of files when you’re editing something important and you want to keep a copy!

# Copy the contents of the file `money.txt` into a file `money.bak`
$ cp money.txt money.bak

# Copy the directory `songs` (and all of its contents) into `songs2`
$ cp -rp songs songs2

rm — Delete files and directories

There’s no recycle bin in Linux so when you use the rm command, your files will be deleted permanently! To delete all files in a folder, you can add the -r (“recursive”) option.

# Delete the file `myfile.txt`
$ rm myfile.txt

# Delete the directory `songs` and all files in it, without prompting! (warning, use this with caution!)
$ rm -rf songs

cat — Print the contents of a file

When you want to see the contents of a file, this is the simplest command to use!

The only problem is it just dumps the entire file to your terminal. So if it’s a big file and you want to navigate around it, use the less command instead.

# Print the contents of `songs.txt`
$ cat songs.txt

chmod — Change the permissions of a file or directory

Each file in Linux has permission settings for three different groups: user (owner) permission, group permission, and other permission.

This command helps you set permissions for each of those three groups.

# Grant all permissions on `myscript.sh` to the user, and execute-only to _group_ and _other_.
$ chmod 755 myscript.sh

# Allow the user to execute `myscript.sh`, and perform no other changes.
$ chmod u+x myscript.sh

chown — Change the owner and group of a file or directory

As well as permissions, a file in Linux can have an owner and be assigned to a group.

This command lets you change the owner or group of a file.

# Change the owner to _dave_ and the group to _staff_ on the file _accounts.txt_.
$ chown dave:staff accounts.txt

diff — Show the difference between two files

Sometimes you want to see which changes were made to a file, or find out if two files are exactly the same. This command helps with that!

# Print the differences between `nyc.txt` and `london.txt`
$ diff nyc.txt london.txt

file — Show the type of a file

Attempts to detect the type of a file (e.g. image, mp3, Java program). It can also detect some binary files too.

This is useful if you want to know what a file is used for, or if the file has been saved without an extension (e.g. like .mp3)

It can usually detect the correct file type, even if the filename has the wrong extension.

# Show the file type of `cilla.mp3`
$ file cilla.mp3

less — Browse the contents of a file

Shows the contents of a file as a set of pages in your terminal. You can use the arrow keys or PageUp/PageDown to scroll through the file.

Very handy for big files!

# Show and scroll the file `songs.txt`. Press `q` to exit.
$ less songs.txt

locate — Find files with names matching a pattern

Searches a database of files on disk, to find a file matching a given pattern.

The database is only updated about once per day, so this is more useful for finding system files.

This is different from which, which looks for commands.

# Find the location of any file called `httpd.conf`
$ locate httpd.conf

tail — Print the last few lines of a file

Very handy if you’re looking at log files, and you want to see the most recent lines in the log.

You can also add -f to “follow” the file, which means that any new lines will be printed to the screen too.

# Print end of file and follow new lines in file `server.log`
$ tail -f server.log

touch — Create a new file or update an existing one

This command is often used to do one of two things: either create a new, empty file, or update the “modified date” on an existing file.

Personally I find it the most useful for creating empty files.

# Create an empty file called `newfile.txt`
$ touch newfile.txt

nano — An interactive file editor

This is the easiest file editor for beginners, because you can type anywhere, and use the arrow keys to move around.

Most of the commands in nano start with ^, which is the Ctrl key. To save a file, see the example below!

# Edit the file `customers.txt` in _nano_
$ nano customers.txt

# Save a file and then exit.
$ Ctrl+O Ctrl+X

vim — An interactive file editor (Intermediate level)

vim means “vi improved”. It’s an improvement on the original “vi” editor.

Everything in vim is controlled with keyboard commands, which can take some time to learn. But once you’ve learned it, you can be very productive!

If you want an easier editor, try nano.

# Edit the file `customers.txt` in _vim_
$ vim customers.txt

dnf — Install and manage packages in RHEL/Fedora

This is the new way to install software in Red Hat Enterprise Linux (RHEL) and its related distros, like Fedora and CentOS.

Previously, in older versions of RHEL/Fedora linux, the package manager was called yum.

🔐 Note you’ll usually need to run this command with sudo.

# Search the online <i>repositories</i> for a package named `curl`
$ dnf search curl

# Install a package called `curl` from the online repositories
$ dnf install curl

# List all packages installed on your system
$ dnf list installed

# Upgrade all packages on your system to the latest compatible versions
$ dnf upgrade

apt — Install and manage packages in Ubuntu

In Ubuntu, you use this command to install and manage packages.

🔐 Note you’ll usually need to run this command with sudo.

# Install a package called `curl` from the online repositories
$ sudo apt install curl

# Uninstall the package called `curl` from your system
$ sudo apt remove curl

curl — Get a web page or API

This is an extremely powerful tool for making HTTP (web) requests. You can use it to hit APIs, fetch a web site, download files from websites and more.

Another solid alternative to this command is wget, but I prefer curl.

# Fetch the Google home page and print the contents
$ curl www.google.com

# Fetch the Google home page and save the HTML to a file
$ curl -o index.html www.google.com

dig — Look up DNS information

DNS is how you translate domain names into IP addresses, and much more.

Using dig can be really useful if you want to find out things like the IP address of a web site, how email is processed (with MX records), and lots more.

# Show the IP addresses for domain _reddit.com_
$ dig +short A reddit.com

ip addr — Show your network configuration

Prints your IP addresses. You’ll usually have multiple IP addresses on your Linux server, depending on how it’s configured.

# Prints a list of all network interfaces, their IP addresses and config
$ ip addr

ping — Check to see if a server is alive

A “ping” is something specific in networking terminology. It means sending a small packet of data to a server and waiting for it to respond.

You’ll sometimes use this if you want to see if a server is alive and responding to requests.

# Send a ping to _www.tutorialworks.com_ to see if it is responding
$ ping www.tutorialworks.com

kill — Terminate a program (process)

When you want to end a process in Linux, you send it a signal. There are different types of signals, the common ones being “TERM” and “KILL”.

“TERM” means terminate, is like a polite request for the command to stop. “KILL” is a bit more forceful - you can use this when a program really needs to terminate now.

# Terminate process number 12345
$ kill 12345

# Forcefully terminate (kill!) process number 12345
$ kill -9 12345

top — Show the top processes

A bit like Task Manager in Windows, this command shows you all of the programs that are running, their process IDs and how much resources they’re using, such as memory and CPU.

We’ve also got a full article about the top command if you want to find out more!

ps — List running processes

Prints a list of the current processes, with their IDs, and the command that was used to start each process.

A good way of finding out exactly which programs you’re currently running!

This command produces a list of processes, so you can filter the list using another tool like grep.

# List all your processes
$ ps

# List all processes matching the string `java`
$ ps -ef | grep java

Ctrl+Z — Suspend a process

This isn’t a command, but it’s a good keyboard shortcut to know.

This will pause a program, if it’s running in the foreground, so you can run something else, or perform another task.

To resume the process again, use the command fg.

fg — Resume a process

Un-pauses or resumes a process which you’ve paused using Ctrl+Z.

jobs — Lists all active jobs (processes)

Lists all of the jobs. This is primarily used when you’ve paused/suspended a few processes and you want to see a list of them.

cat /etc/redhat-release — Show Linux distribution name & version

Show the current version of your Linux distribution.

You’ll notice that this is actually a file! This file is created when you install Linux. Here we’re just using cat to show the file’s contents.

# Show the Linux distribution name and version
$ cat /etc/redhat-release

date — Show the current date and time

Your server has a date and time set. It also has a time zone too. This will be used whenever the server writes files.

So it’s good to confirm that your server is set with the correct time and timezone.

df — Show free disk space

Want to find out how much disk space you have left? This command does it.

You can change the output in a few different ways to make it more human-readable (see the example below).

# Show free disk space with human-readable sizes
$ df -h

du — Show disk space usage

This is the opposite of the df command. It shows how much space your files and folders are taking up.

It can be handy to figure out where all your space is disappearing to!

# Show disk usage (in human-readable sizes) of all top-level directories
$ du -h -d 1 /

shutdown — Halt or reboot your machine

Getting ready to shut down your server? Use this command.

Be careful that nobody else is using the server at the same time. :-)

🔐 Note you’ll usually need to run this command with sudo.

# Reboot the system now
$ shutdown -r now

uname — Print system information

Shows information about the Linux kernel.

# Show all info about the Linux kernel, including version number.
$ uname -a

uptime — Show how long the system has been running

Use this to check whether your system has been running without problems, or whether it’s been restarted at some point recently.