Cheat sheet · 7 commands

Disk & memory

df answers "how full is the disk", du answers "what is filling it", and free answers the same questions for RAM. The drill-down on this sheet finds a runaway directory in under a minute.

The 3 you will use every day

Free space per filesystem

The disk-hunt drill-down

Memory: read "available", not "free"

The full sheet

Free space per filesystemguide ›
Inode usage (full disk with free bytes?)guide ›
Total size of a directoryguide ›
The disk-hunt drill-downguide ›
Memory: read "available", not "free"guide ›
Block devices and where they are mounted
What is mounted where

Practise these for real in the interactive course, or keep every sheet, chapter and fix in one book: The Linux Command Line Handbook.