Linux Commands

Command references for core Linux tools, syntax, examples, and practical one-liners.

ln command in Linux for creating symbolic links

Jul 31, 2026 • 11 min read

How to Create Symlinks in Linux with ln

The ln command creates symbolic links on Linux, giving you a stable name that points to a moving target. This guide covers creating, updating, and cleaning up symlinks, plus the -sfn pattern used for atomic deploys.

Jul 30, 2026 • 7 min read

cat Command in Linux: View, Combine, and Create Files

Display, combine, and create files with the cat command in Linux, plus line numbers, hidden characters, and when to use less instead.

Jul 28, 2026 • 7 min read

Understanding the /etc/shadow File in Linux

The /etc/shadow file stores hashed passwords and password aging data for each user on a Linux system. This guide explains the file format, hash types, field meanings, and how to query password information safely.

Jul 27, 2026 • 12 min read • series

ssh Command in Linux: Connect to Remote Servers

The ssh command connects you to a remote Linux server. This guide covers its syntax, the most useful options, key-based login, and port forwarding.

Using the ssh command to connect to a remote Linux server

Jul 27, 2026 • 6 min read • new

update-alternatives Command on Ubuntu and Debian

Use update-alternatives on Ubuntu and Debian to list, register, switch, and remove program alternatives, with automatic and manual mode examples.

Program paths converging through an update-alternatives selector to one default command

Jul 25, 2026 • 7 min read • new

How to Find Which Process Is Using a Port in Linux

Find the Linux process listening on a TCP or UDP port with ss, lsof, fuser, or netstat, then inspect and stop it safely.

Finding the process that is listening on a network port in Linux

Jul 22, 2026 • 5 min read

Linux uname Command: Print System Information

The uname command prints kernel name, version, architecture, and hostname. This guide covers all uname options with examples and practical scripting uses.

Using the uname command to print system information in Linux

Jul 21, 2026 • 8 min read

which Command in Linux: Find Executable Locations

Use the which command to locate executables in PATH, list every match, and check command availability. Compare which with command -v, type, and whereis.

Using the which command in Linux to find executable locations

Jul 21, 2026 • 6 min read

How to Set or Change the Time Zone in Linux

Check and change the Linux system time zone with timedatectl, choose the correct Region/City value, verify /etc/localtime, and handle non-systemd systems.

Globe illustration representing Linux time zone settings

Jul 21, 2026 • 5 min read

head Command in Linux: Print the First N Lines of a File

The head command prints the first lines or bytes of a file. This guide shows how to display a specific number of lines, preview files, and limit command output in pipelines.

Using the head command in Linux to display the first lines of a file

Jul 21, 2026 • 7 min read

lsusb, lspci, and lshw: List Hardware in Linux

Identify the hardware in a Linux machine: list USB devices with lsusb, find PCI cards and their drivers with lspci, and get a full inventory with lshw.

Listing PCI and USB hardware devices in a Linux terminal

Jul 20, 2026 • 6 min read

tail Command in Linux: Show Last Lines and Follow Logs

Use the Linux tail command to show the last N lines or bytes of a file, follow logs in real time with tail -f, and filter live output with grep.

Terminal window showing the tail command following a Linux log file in real time

Jul 19, 2026 • 9 min read • series

umask Command in Linux: Set Default File Permissions

The umask command sets the default permission mask for newly created files and directories. This guide explains how umask works, how to calculate its value, and how to make it permanent.

Setting default file permissions with the Linux umask command

Jul 19, 2026 • 5 min read • series

export Command in Linux: Set Bash Environment Variables

Use export to turn Bash shell variables into environment variables that child processes inherit, list exported variables, and make them permanent across sessions.

Developer using the export command in a Linux terminal beside the Tux mascot

Jul 18, 2026 • 8 min read

lsof Command in Linux: Find Open Files and What Is Using a Port

Use the lsof command to find what is using a port, identify processes holding files open, and locate deleted files that still consume disk space.

Using the lsof command to list open files and network connections in Linux

Jul 17, 2026 • 4 min read

How to Unzip a .gz File in Linux

Unzip a .gz file in Linux with gzip or gunzip, keep the original file when needed, and extract .tar.gz archives with tar.

GZ file icon beside the text unzip .gz file on a yellow background

Jul 16, 2026 • 8 min read

sha256sum and md5sum: Verify Checksums in Linux

Check a file's SHA-256 or MD5 checksum in Linux: generate digests with sha256sum and md5sum, verify SHA256SUMS lists with -c, and confirm ISO downloads.

Verifying file integrity with sha256sum and md5sum in Linux

Jul 16, 2026 • 4 min read

What Is stdin, stdout, and stderr in Linux

stdin, stdout, and stderr are Linux's three standard streams. See how file descriptors 0, 1, and 2 connect commands to terminals, files, and pipes.

Diagram of stdin entering a Linux process and stdout and stderr leaving it

Jul 14, 2026 • 5 min read

less Command in Linux: Navigate and Search Files

How to use the less command in Linux to view files page by page, search for text, follow log files in real time, and navigate with vi-style key bindings.

Jul 13, 2026 • 6 min read • series

passwd Command in Linux: Change User Passwords

Change your own, another user's, or the root password in Linux with the passwd command. Covers password expiry with chage, forcing a change at next login, and account locking.