The Most Important Linux Commands (With Examples)

Linux is the operating system that powers over 90% of websites on the internet. If you’ve ever hosted a website before, then you probably have some level of experience with Linux in the form of it’s more user-friendly cousin: cPanel.

To become an expert at cloud computing, however, you’ll have to learn how to operate Linux servers without the help of a graphical user-interface such as cPanel. Although it may sound intimidating at first, getting comfortable with operating Linux servers starts with getting comfortable using the Linux Shell.

What is the Linux Shell/Terminal?

An example of an SSH terminal showing the ‘command line interface’.

The Linux shell, also commonly referred to as the ‘terminal‘ is the gateway to the back-end of your web server. It uses a ‘command-line-interface’, which doesn’t include the pretty-icons and user friendly experience found in ‘graphical user interfaces‘. From here on out, in order to make changes to your server, you’ll need to input text commands directly into the shell.

Important Linux Commands With Examples

In this tutorial, you will learn the basic Linux commands for beginners who are getting started in Cloud Computing. Each of the commands listed in this tutorial are the most commonly used commands in the WordPress on Google Cloud tutorials on onepagezen.com.

1. User Permissions

sudo

The sudo command is used to run a single command with root permissions. In the example above, the command sudo is used before the command apachectl restart in order to grant the user the level of permissions required to restart the Apache server.

In the example above, the sudo -i command is used to instill root permissions to the user for the entire duration of the SSH session. Notice how the username changes to ‘root’.

2. File and Directory Management

touch

The command touch is used to create new files. In the example above, the command touch is used to create a new file called myfile.txt in the home directory.

echo

The command echo is used to insert text into an existing file. In the example above, the command echo «Hello World» >> /home/myfile.txt is used to insert the text “Hello World” into the file called myfile.txt.

cat

The command cat is used to display the contents of a file in the terminal. In the example above, the command cat /home/myfile.txt is used to display the contents of a file called myfile.txt.

mkdir

The command mkdir is used to create new directories. In the example above, the command mkdir /home/mydirectory is used to create a directory called mydirectory inside of the home directory.

mv

The command mv is used to move files. In the example above, the command mv /home/myfile.txt /home/mydirectory is used to move the file called myfile.txt into the directory called mydirectory.

NOTE: Remember to move your myfile.txt file back to the home directory. You can do this by running mv /home/mydirectory/myfile.txt /home

ls

The command ls is used to list directory contents. In the example above, the command ls /home/mydirectory is used to list the contents of the directory called mydirectory.

wget

The command wget is used to download repositories to your Linux machine. In the example above, the command wget https://dl.eff.org/certbot-auto is used to retrieve the certbot-auto repository from eff.org and download it to my virtual machine.

find

FOR FILE: The command find is used to locate a file or directory. In the example above, the command find / -type f -name wp-config.php is used to locate the file called wp-config.php.

FOR DIRECTORY: In the example above, the command find / -type d -name etc is used to locate the directory called etc.

stat

FOR FILE: The command stat is used to retrieve information about a file or directory. In the example above, the command stat -c «%a %n» /home/myfile.txt is used to find the permission level of the file called myfile.txt.

FOR DIRECTORY: In the example above, the command stat -c «%a %n» /home/mydirectory is used to determine the permission level of the file called mydirectory.

chmod

FOR FILE: The command chmod is used to modify file and directory permissions. In the example above, the command chmod 755 /home/myfile.txt is used to change the permission level of the file called myfile.txt to 755.

FOR DIRECTORY: In the example above, the command chmod -R 755 /home/mydirectory is used to change the permission level of the directory called mydirectory to 755. By adding -R, the command becomes recursive, meaning that all of the files contained inside of the directory will inherit the permission changes.

rm

FOR FILE: The rm command is used to delete a file or directory. In the example above, the command rm /home/myfile.txt is used to delete the file called myfile.txt from the home directory.

FOR DIRECTORY: In the example above, the command rm -R /home/mydirectory is used to delete the directory called mydirectory and all of it’s contents.

3. Apache Server Management

apachectl

START APACHE: The apachectl command is used to control the behavior of your Apache server. In the example above, the command sudo apachectl start is used to start your Apache server.

STOP APACHE: In the example above, the command sudo apachectl stop is used to stop your Apache server.

RESTART APACHE: In the example above, the command sudo apachectl restart is used to restart your Apache server.

TEST APACHE: In the example above, the command sudo apachectl configtest is used to check if your Apache server is configured properly.

httpd

The httpd series of commands are used to make changes to your HTTP server, and are oftentimes used interchangeable with the apachectl commands. In the example above, the command httpd -v is used to check the current version of Apache currently running on the server.

In the example above, the command httpd status is used to check the health of your Apache server.

Bitnami Apache Server Configurations

/opt/bitnami/ctlscript.sh

START APACHE: The ctlscript is used to control the behavior of your Apache servers running Bitnami stacks, in the same way that apachectl is used in the previous examples. In the example above, the command /opt/bitnami/ctlscript.sh start apache is used to start an Apache server running a Bitnami WordPress stack.

STOP APACHE: In the example above, the command sudo /opt/bitnami/ctlscript.sh stop apache is used to stop an Apache server running a Bitnami WordPress stack.

RESTART APACHE: In the example above, the command sudo /opt/bitnami/ctlscript.sh restart apache is used to restart an Apache server running a Bitnami WordPress stack.

TEST APACHE: In the example above, the command sudo /opt/bitnami/ctlscript.sh status is used to check the health of an Apache server running a Bitnami WordPress stack.

4. Virtual Machine Management

lsb_release

The lsb_release command is used to determine the Linux distribution being used. In the example above, the command lsb_release -a is used to check the current version of the virtual machine’s Linux operating system.

df

The command df is used to check the available disk space on a machine.
man

The man command is used to show the different options available for a specific command. In the example above, the command man ls is used to view information about the options available for the ls command.

Did it Work?

This is just a small list of the most commonly used Linux commands, there are literally hundreds more!

If you thought of any important commands that were missing from the list, or if you would like to share a question or comment, please post your message below! Thanks!