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Linux Survival Basics

Read-only

Find the Largest Installed Packages

A Debian or Ubuntu system is low on disk and you need to see which installed packages occupy the most space.

Command

dpkg-query -W -f='${Installed-Size}\t${Package}\n' | sort -nr | head -20

Before you run this

System impact: Read-only. Low when scoped to the shown target.

When not to use it: Do not remove large packages just because they are large; kernels, runtimes, and databases may be required.

Expected output

A size-sorted list of installed packages by KiB.

System impact

Read-only. Nothing changes. dpkg-query prints installed package sizes from metadata and sorts the largest first.

Recovery / rollback: no state is changed.

When to use it

Use before cleanup conversations, image slimming, or deciding which package families deserve review.

When not to use it

Do not remove large packages just because they are large; kernels, runtimes, and databases may be required.

Watch this command run

Command transcript

This sanitized transcript shows the commands and output shape without exposing host details.

demo@lab:~$

$ dpkg-query -W -f='${Installed-Size}\t${Package}\n' | sort -nr | head -20

132904	linux-image-6.8.0-60-generic
52288	python3
18320	nginx
8420	openssl
7488	curl
7240	libc6
6800	bash
980	base-files
256	zlib1g
250	zlib1g:i386

$ dpkg-query -W -f='${Installed-Size}\t${Package}\n' | sort -nr | head -5

132904	linux-image-6.8.0-60-generic
52288	python3
18320	nginx
8420	openssl
7488	curl
View commands shown

These are the commands shown in the sanitized transcript.

Commands shown

  1. dpkg-query -W -f='${Installed-Size}\t${Package}\n' | sort -nr | head -20
  2. dpkg-query -W -f='${Installed-Size}\t${Package}\n' | sort -nr | head -5

next steps

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Find Broken or Leftover dpkg States

Not every package row is cleanly installed.

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Find the Largest CI Logs

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find logs/ -type f -printf '%s %p\n' | sort -nr | head -10
Study mapping

Use this as independent command practice: read the notes, predict the output, then compare it with the example before using a real shell.

  • lpic1:102-package-management
  • lpic1:103-gnu-unix-commands
  • lfcs:essential-commands
  • lfcs:operations-deployment
  • linuxplus:automation-scripting
  • linuxplus:provisional
  • linuxplus:system-management
  • risk:read-only

Useful for

  • LPIC-1 style command-line practice
  • LFCS style performance tasks
  • Linux+ style troubleshooting review

Independent study support only. No affiliation, endorsement, exam dumps, or real exam questions.