Linux Survival Basics

Find Which Folder Is Filling the Disk

A server is low on disk and you need a quick folder-level view before drilling into files.

Command

du -sh /var/* 2>/dev/null | sort -h

What changed

Nothing changes. The command prints human-readable folder sizes and sorts them.

Danger

safe

When to use it

Use this before deeper `find` searches or cleanup decisions.

When not to use it

Avoid assuming the largest folder is safe to delete; size is not ownership or importance.

Undo or recovery

No state is changed.

Expected output

A sorted list of directory sizes under `/var`.

demo script

Disposable terminal steps

df -h
du -sh /var/* 2>/dev/null | sort -h
du -sh /var/log /var/cache /var/backups 2>/dev/null

Terminal transcript Demo JSON

simulated output

What it looks like

disposable vessel

::fixture-ready::
$ df -h
Filesystem      Size  Used Avail Use% Mounted on
overlay         3.6T  1.2T  2.3T  35% /
tmpfs            64M     0   64M   0% /dev
shm              64M     0   64M   0% /dev/shm
tmpfs            64M     0   64M   0% /tmp
tmpfs            64M  352K   64M   1% /var
/dev/nvme0n1p2  3.6T  1.2T  2.3T  35% /lab/demo.sh
tmpfs            63G     0   63G   0% /proc/asound
tmpfs            63G     0   63G   0% /proc/acpi
tmpfs            63G     0   63G   0% /proc/scsi
tmpfs            63G     0   63G   0% /sys/firmware
tmpfs            63G     0   63G   0% /sys/devices/virtual/powercap
::exit-code::0
$ du -sh /var/* 2>/dev/null | sort -h
64K	/var/backups
96K	/var/log
192K	/var/cache
::exit-code::0
$ du -sh /var/log /var/cache /var/backups 2>/dev/null
96K	/var/log
192K	/var/cache
64K	/var/backups
::exit-code::0

YouTube Short

Find the folder filling your disk.

Start broad. Find the folder that is growing before you chase individual files.

experiments

A/B tests to run

Metric: search_click_rate

A: Find which folder is filling the disk.

B: Start disk cleanup with this broad check.