How to uninstall non dependency packages?

Question

How do you find all packages that were manually installed which are not a dependency of any other installed packages?

Answer 1

The short answer is: use aptitude like in the following:

aptitude -F%p search '?installed?not(?automatic)

But unfortunately this command returns many packages that match the query but are not what you expect, for two reasons:

1. there are packages installed during initial installation of the system that result as non automatically installed

2. packages installed as dependencies of a metapackage also can result as non automatically installed

The solution I came to some time ago is a match between the preceding command and the dpkg logs, that at least try to remove the influence of the point 1. in the preceding problems' list:

#!/bin/bash

export LC_COLLATE=C

eval $(lesspipe)

vars=($(less $(ls -rt /var/log/dpkg.log*) | grep 'status installed grub-pc' | head -1))
date="${vars[0]}"
time="${vars[1]}"

join \
  <(aptitude -F%p search '?installed?not(?automatic)' |
    sort) \
  <(less $(ls -rt /var/log/dpkg.log*) |
    awk -v date=$date -v time=$time '(($1 == date && $2 > time) || $1 > date) && $3 == "install" { print $4, $1, $2 }' |
    sort -u) |
  awk '{ print $2, $3, $1 }' |
  sort

This assume that grub-pc is the last package installed during initial installation, and is in no way perfect, but can give you a rough information to start from.