Linux Commands
Command references for core Linux tools, syntax, examples, and practical one-liners.
Regular Expressions Explained: How Regex Patterns Work
Regular expressions explained from the ground up: how anchors, character classes, quantifiers, and groups build patterns that work in grep, sed, and awk.
zip Command in Linux: Zip Files and Directories
Create ZIP archives in Linux with the zip command. Zip directories recursively, exclude files, add a password, and split large archives.
git worktree: Work on Multiple Branches at Once
Use git worktree to check out multiple branches in separate directories, handle urgent fixes without stashing, and clean up linked worktrees safely.
git log Command: View Commit History
Browse commit history with git log: show the last commit, filter by author, date, or keyword, search by code change, track a file across renames, and read branch graphs.
whoami Command in Linux: Display the Current User Name
The whoami command shows the current effective username on Linux. This guide explains syntax, practical examples, shell script usage, and how it compares to id -un and $USER.
killall Command in Linux: Kill Processes by Name
Use the Linux killall command to stop processes by name, select signals, filter by user or age, confirm matches, and compare killall with kill and pkill.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
