du
Reading the systemPackage: coreutils
The space a directory and its contents actually take. df says how much is missing; du -sh /* | sort -h says where it went.
What its options do in the lessons
From the same glossary the lessons render under their commands, so the two cannot disagree.
du -h- Human-readable sizes.
du -s- One total per argument, without listing what is inside.
du --max-depth- Limits how deep the report goes.
--max-depth=1gives one total per subdirectory: that is how you find what is filling a disk.
Lessons that teach it
- What the panel limits, and what its backups do not coverISPConfig: hosting several sites on one server
- Files, retention and off-site copiesBackups and restores
- Disk, memory and load: reading them correctlyMonitoring a server
- What an output proves, and what "success" does notDiagnosing a failure: what each output proves
- pg_wal fills, and something is holding itAdministering PostgreSQL: access, connections and growth