How do I display the disk space purging a package would free under Debian?

Question

I would like to remove unneeded packages. I have already removed large files (using k4dirstat) and the only left bit is a few hundreds of packages I installed but I do not use most of them (the install, without /home, takes 15GB).

It is possible to remove a package with dependencies individually using 'apt-get purge', and to see space that would be freed. However, this way to see space a package occupies is slow and manual, which is a problem.

How do I display packages with the disk space purging them would free under Debian?

Answer 1

This was definitely an interesting question. It seems that the only thing I've ever seen give me the "XX will be freed" output is "apt-get remove". Even more oddly, it doesn't give you that line with the -s ("dry run") command line option.

WARNING[0]: That means that using apt-get to determine the output needs to run as root. So, for the love of Bob, MAKE SURE to test it on an expendable VM first!

WARNING[1]: Make sure you know what you're doing before you start removing packages. This will go through EVERY package on the system and see how much space would be recovered (as reported by apt-get) if it were removed. This doesn't mean they are SAFE to remove. I disclaim all responsibility!

Also worth mentioning: This will likely be very, very slow. Hopefully, this is something you're looking to run situationally, as the need arises, rather than repeatedly.

That said, I offer you my final kluge of 2013. Hopefully it helps.

#!/bin/bash 
for I in `dpkg --get-selections | grep install | grep -v adduser | grep -v apt | awk '{print $1}'`; 
do
    echo -n "$I : "
    apt-get --assume-no --purge remove $I | grep "will be freed" | awk '{print $4, $5}' >> ~/package_script.out
done

I wrote and tested it under ubuntu, so it should work fine for debian et al.

Update: I added a filter to remove the adduser and apt packages from consideration. The former is too "core" to remove and takes forever, the latter locks seemingly permanently. A There are probably more packages like that...

Answer 2

You can also follow the same basic idea as suggested by @GeminiDomino but only for the packages you specify:

sudo apt-get --assume-no --purge remove PACKAGE | grep "will be freed" | 
  awk '{print $4, $5}' 

You can turn this into a function by adding these lines to your ~/.bashrc:

space_freed(){
    sudo apt-get --assume-no --purge remove "$@" | grep "freed.$" | 
      awk '{print $4, $5}' 
}

And then you can give multiple package names from the commandline:

$ space_freed thunderbird firefox chromium
239 MB

---

I had kind of assumed you would know the package names since otherwise this will take quite a while. Still, you could use my approach to list the sizes of all packages. This command will print the names of all installed packages:

$ dpkg -l | awk '($1=="ii"){print $2}'

If you run space_freed on each line output by that command, you will get a list of all installed packages and the space freed by uninstalling them:

for i in $(dpkg -l | awk '($1=="ii"){print $2}'); do  
 echo -e "$i\t"$(space_freed $i); 
done

---

The easiest way is to use wajig to list the largest installed packages:

wajig large

Answer 3

Displaying package sizes

Synaptic :

Go to "Settings>Preferences" and choose "Columns and Fonts", then tick "Installed size".

dpkg-query :

dpkg-query --showformat='${Package}\n${Description}' -W {package-names/patterns}

Displaying largest installed packages (source)

dpkg-query -Wf '${Installed-Size}\t${Package}\n' | sort -n

wajig large

dpigs

sed -ne '/^Package: \(.*\)/{s//\1/;h;};/^Installed-Size: \(.*\)/{s//\1/;G;s/\n/ /;p;}' /var/lib/dpkg/status | sort -rn

awk '{if ($1 ~ /Package/) p = $2; if ($1 ~ /Installed/) printf("%9d %s\n", $2, p)}' /var/lib/dpkg/status | sort -n | tail

Answer 4

Give aptitude a try... it's a cli based package manager with easy to use keybindgs. You can see how much space will be freed by purging a set of packages in the upper right corner of the interface.