Articles by Dejan Panovski
How to Install Docker on Ubuntu 26.04
Install Docker on Ubuntu 26.04 from the official Docker repository. Covers repository setup, verification, running without sudo, updates, and uninstall steps.
Set up PostfixAdmin on Ubuntu 26.04
Set up PostfixAdmin on Ubuntu 26.04 with Nginx, PHP, MySQL, DNS records, and a Let's Encrypt certificate for a virtual mail server.
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 Convert MP4 to MP3 with ffmpeg
Convert MP4 video to MP3 audio from the Linux command line with ffmpeg, including quality settings, lossless extraction, trimming, and batch conversion.
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.
CIDR Notation and Subnetting Explained
CIDR notation defines IP network size with a prefix length. This guide explains subnet masks, address ranges, host counts, and practical IPv4 subnetting.
SSH Connection Refused: Causes and Fixes
Fix the SSH "Connection refused" error by checking the destination, listening port, OpenSSH service or socket, firewall rules, and port forwarding.
How to Connect to a Docker Container
This guide explains how to connect to a running Docker container using docker exec and docker attach, with examples for getting a shell, running commands, and viewing logs.
Dockerfile COPY vs ADD: Which to Use
Compare Dockerfile COPY and ADD for local files, build stages, remote URLs, Git repositories, and tar extraction, with clear guidance on when to use each.
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.
How to Comment Out Multiple Lines in Vim
Comment out multiple lines in Vim with visual block mode, line ranges, or bundled gc mappings, then remove comments with the matching commands.
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.
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.
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.
How to Check Java Version
Find out which Java version is installed on your system, check the JDK compiler version, and manage multiple Java installations from the command line.
