vim and nano — Editing Files in a Terminal
Sooner or later you will SSH into a server, type vim or find yourself dropped into it by git commit, and discover that nothing you try makes it stop. This…
Disks and Mounting — lsblk, mount and fstab
Linux does not have drive letters. Every filesystem is grafted onto a single tree at a mount point — a directory that becomes the doorway to that storage. Once that…
Package Management — apt, dnf and pacman
Every distribution installs software from repositories, and every distribution family uses a different command to do it. The concepts are nearly identical; only the spelling changes. This page puts the…
curl and wget — Fetch Things Over HTTP
Both fetch things over HTTP. The difference in practice: curl is for talking to things — APIs, headers, authentication, sending data. wget is for taking things — downloading files, resuming,…
ln — Hard Links and Symbolic Links
Linux has two kinds of link and they are not variations on the same idea — they work at different levels of the filesystem. Understanding the difference takes one paragraph…
Networking Basics — ip, ss, ping and dig
“The network is broken” is four or five different problems wearing the same coat. These commands tell them apart: is there an address, is anything listening, can packets reach the…
awk — Process Text by Fields
Where grep finds lines and sed edits them, awk understands that a line has columns. That one idea is why it survives: any time your data has fields — log…
Disk Space — df, du and ncdu
Sooner or later a Linux machine tells you No space left on device and something stops working. This page is the sequence for finding out what filled up and getting…
cron — Schedule Recurring Jobs
cron runs commands on a schedule. It has done so since the 1970s, it is on every Linux system, and it fails in a small number of extremely predictable ways…
Processes — ps, top and htop
When a machine is slow, unresponsive, or something is running that should not be, these are the tools that tell you what is actually happening. ps takes a snapshot, top…