Tutorials

A service that will not accept a connection can leave you checking which ports Linux is listening on. netstat shows network connections and listening ports, while nslookup queries DNS records for a hostname. This article shows how to inspect listening ports with netstat and ss, then check a hostname’s DNS answer with nslookup. TL;DR Use

A Linux account may need access to a shared directory or device that is controlled by a group. The usermod command adds an existing account to a supplementary group, an additional membership that does not change its primary group. I’ll show how to add an account to one or more groups and check its membership

A machine set to UTC may show a different local time than you expect. Its timezone applies regional rules to the system clock to produce local date and time. This article explains how to find a zone name and change the Linux timezone with timedatectl. TL;DR: Change the Linux timezone Use timedatectl to choose an

A short status message is often all a shell script needs to show while it runs. The Bash echo command writes its arguments to standard output and normally adds a newline. I’ll show how to print text and variables, then explain when echo behaves differently across shells. TL;DR: Echo command in Linux The Bash echo

Moving between folders in a terminal starts with knowing which directory the shell is working in. The cd command changes the shell’s current directory to a path or a destination such as your home directory. This article explains how to choose a path to a directory and use cd’s shortcuts to move from there. TL;DR

A Debian-based system can show apt and apt-get in package instructions, making it unclear which one to type. Both commands let you request package operations through APT, which uses repository information to resolve dependencies. I’ll explain where their commands differ and how upgrades and dpkg fit into the choice. TL;DR: apt vs apt-get Use apt

A list of numbers in a file may look out of order when Linux compares each line as text. The sort command can compare numeric values instead and write the lines in numeric order. I’ll show how to sort numbers in either direction and save or check the result. TL;DR Use sort to order text

A log file can hold more lines than you can scan by eye when you need to find an error message. grep is a command-line tool that searches text and prints the lines that match. I’ll show you how to search a file with grep and read its matches and exit status. TL;DR: Search for