Essential Linux Commands

The following outlines Essential Linux Commands that form a great foundation when starting out with Linux and other Unix-based systems.

Linux is everywhere — it powers over 70% of the world’s servers and dominates cloud infrastructure. You'll find Linux running on web servers, networking equipment, IoT devices, embedded systems, mobile phones, and more. From data centers to smart homes, Linux is at the core of modern computing.

For anyone working with Linux, having a strong command-line foundation is essential and beneficial depending on what circumstances are encountered. In this blog, I’ll share some Essential Linux Commands that are fundamental and go a long way in helping to navigate the filesystem and work confidently in a Linux terminal.

pwd

Print Working Directory

What it does: Shows where you are in the filesystem.

ls

List Files and Directories

What it does: Lists the contents of the current directory.

Running ls -l with the -l flag provides a long listing format for detailed output:

cd

Change Directory

What it does: Moves between directories.

This example changes from the /home/mt directory to the /var/log directory:

mkdir

Make Directory

What it does: Creates new directories/folders.

cp

Copy Files and Directories

What it does: Copies a file or directory to another location.

In this example, the cp command is used to copy a file from one directory to another. The file notes.txt is copied from the /home/mt/Documents directory to the /home/mt/Downloads directory. This demonstrates how cp allows you to duplicate files while keeping the original intact in its current location.

mv

Move or Rename Files

What it does: Moves or renames files or directories.

In this example, the mv command is used to move a file from one directory to another. The file notes.txt, located in the Downloads directory, is moved to the Documents directory by specifying the full source and destination paths. This demonstrates how mv can be used to relocate files across directories in the filesystem.

In this example, the mv command is used to rename a file. The original file notes.txt is renamed to notes1.txt by specifying the old name as the source and the new name as the destination. This shows how mv can be used not only to move files between directories but also to rename them within the same location.

touch

Create an Empty File

What it does: Quickly creates a new, empty file or updates the timestamp of an existing one.

In this example, the touch command creates a file named notes.txt:

In this example, the touch command is used to update the timestamp of an existing file after using the mv command to change the name to notes1.txt. The file notes1.txt already exists, and running touch notes1.txt updates its last modified time to the current time, as shown by the updated timestamp in the second ls -l output. This is useful for signaling recent activity or triggering automation tools that monitor file changes.

rm

Remove Files

What it does: Deletes files from the filesystem.

rm -r

Remove Directories Recursively

What it does: Deletes a directory and all of its contents.

Before running rm -r, multiple commands are chained together on one line to first create a directory, navigate into it, create two files, and list the contents. This is a neat feature in Linux that allows you to execute several commands in a sequence using semicolons (;), making it easier to automate or set up demo environments quickly without writing a script.

cat

Concatenate and Display File Contents

What it does: Displays the contents of files.

This example concatenates the contents of the /etc/os-release file to display the Linux distribution information:

head

View the Beginning of a File

What it does: Displays the first 10 lines of a file.

tail

View the End of a File

What it does: Displays the last 10 lines of a file.

grep

Search Inside Files

What it does: Searches for patterns in text files.

This example searches for "error" in the /var/log/syslog file:

ps

Process Status

What it does: Lists active processes running under your session.

The basic ps command shows the processes associated with the current terminal session. However, running ps aux expands the view to include:

• Processes from all users (a)
• Additional details like user, CPU usage, memory usage (u)
• Processes that are not attached to a terminal (x)

This makes ps aux especially useful for checking system-wide activity or when piping into grep to look for specific services.

top / htop

What it does: Displays a live system monitor for processes and resource usage.

The top and htop commands are essentially Task Manager (Windows), in the Linux environment.

top

Typing top into the Linux terminal and pressing Enter brings this up in the terminal output:

htop

Interactive Process Viewer

The htop command is an enhanced interactive alternative in constrast to top.

Typing htop into the Linux terminal and pressing Enter brings this up in terminal output:

chmod

Change File Permissions

What it does: Modifies read/write/execute permissions for users or groups.

In this example, the chmod command is used to remove write permissions from a file. The -w flag modifies the file's permissions by taking away the ability to write to it. This is useful when you want to protect a file from accidental edits while still allowing it to be read or executed.

In this example, the chmod command is used to make the script.sh file executable with +x:

chown

Change File Ownership

In this example, the command: sudo chown root:root script.sh does the following:

• sudo — runs the command with elevated privileges, which are required for changing ownership.
• chown — invokes the change ownership command.
• root:root — assigns ownership to the user root and the group root.
• script.sh — is the target file whose ownership is being changed.

This means that after running the command, only the root user (and root group) will own the file script.sh, which may restrict access for other users.

man

Manual Pages

What it does: Displays built-in documentation for any Linux command.

This is the best way to learn options, syntax, and usage examples for different commands.

This example shows the documentation for the grep command:

sudo

Superuser Do

What it does: Executes commands with elevated privileges. The sudo command allows a regular user to run specific commands as the root user, typically with a password prompt. In contrast, sudo su elevates the current user to a full root shell session — meaning all following commands will be executed as root until the session ends. Both are essential for system-level changes and administrative tasks.

Mastering these commands builds a solid foundation for working with Linux. They're usually the first tools you rely on when navigating the filesystem and handling everyday tasks.

What are some of your favorite Linux commands?