List optional dependencies with pacman on arch linux

Question

I'm using arch linux.

Is there a way to list optional dependencies of all installed packages? And if yes, can I filter this list to see only the missing (not installed) packages?

Answer 1

You can use expac to query the pacmandatabase.

Something like:

awk 'NF>=2' <(expac "%n %O") > optdeps

will print a list of all the installed packages on your machine and the optdepends for each one (%O)¹ to a file called optdeps. You could then sort this against a list of installed optdepends packages.

See man expac for the complete list of options.

^{1. That is an upper case O, not a zero. Because we can't have a font that distinguished between the two...}

Answer 2

Though I've had to notice that @DarkHeart's solution doesn't really work, it inspired me to make a working one. (no colours, though)

I'm using package-query, a similar tool instead of expac which was suggested by @jasonwryan, because I've had it already installed (it's a dependency of yaourt). It should be trivial to change this to use expac instead.

The listing of all optional dependencies is mostly done by the call to package-query. The first for-loop removes the explanations, so just the package names for the optional dependencies remain; the second for-loop removes the already installed dependencies in its first line before printing the results in the second one.

#!/usr/bin/perl
use strict;
use warnings;

my %deps;
for (`package-query -Q -f'%n %O'`) {
    $deps{ (/^(\S+)/)[0] } = [/(\S+):/g];
}
my @pkgs = keys %deps;
for my $pkg (@pkgs) {
    my @missing_deps = grep { !($_ ~~ @pkgs) } @{ $deps{$pkg} };
    print "$pkg => @missing_deps\n" if @missing_deps;
}

Answer 3

This is not exactly efficient, but will find what you want (in COLOR!):

pacman -Q > /tmp/paccache
for pkg in $(awk '{print $1}' /tmp/paccache) ; do 
   echo -n "$pkg => "; 
   for dep in $(pacman -Qi $pkg | awk -F: '/Optional Deps/{gsub(/[\<\>=].*/,"");print $NF;}' ) ; do 
       grep -q "$dep" /tmp/paccache && COLOR=32 ; echo -en "\e[1;${COLOR:-31}m${dep}\e[0;m " ; unset COLOR ; 
   done 
   echo
done