Minimizes a list of debian packages by removing those implied as dependencies of the others

mindeps.py

#!/usr/bin/env python3

#######################################################################
# This program is free software; you can redistribute it and/or       #
# modify it under the terms of the GNU General Public License as      #
# published by the Free Software Foundation; either version 2 of the  #
# License, or (at your option) any later version.                     #
#                                                                     #
# This program is distributed in the hope that it will be useful, but #
# WITHOUT ANY WARRANTY; without even the implied warranty of          #
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU   #
# General Public License for more details.                            #
#                                                                     #
# Written and (c) by Francois Garillot                                #
# Contact <francois@garillot.net> for comment & bug reports           #
#######################################################################

import re
import sys
import subprocess

def getpipeoutput(cmds, *, quiet=False):
    cmd_str = " | ".join(cmds)
    if not quiet:
        print(f">> {cmd_str}", end=" ")
        sys.stdout.flush()
    output = subprocess.check_output(cmd_str, shell=True).decode().rstrip("\n")
    return output

def get_crazyformat_reqs(pack, dependtypes):
    cmd = f"apt-cache depends {pack} 2> /dev/null"
    folist = getpipeoutput([cmd], quiet=True).split("\n")
    foreqs = {}
    for req in dependtypes:
        reqlist = [s for s in folist if req in s]
        foreqs[req] = [s.rpartition(": ")[2].strip() for s in reqlist]
    return foreqs

def get_saneformat_stg(pack):
    cmd = f"apt-cache showpkg {pack} 2> /dev/null | grep -A 1 Dependencies | tail -n 1"
    fostr = getpipeoutput([cmd], quiet=True)
    fostr = fostr.partition(" - ")[2]
    return re.sub(r"\s\(\d+\s.*?\)\s", " ", fostr).split()

def build_graph(vertexes):
    wanted = {"Depends"}
    fodepends = set()
    for pack in vertexes:
        crazydepends = get_crazyformat_reqs(pack, wanted)
        sanedeps = set(get_saneformat_stg(pack))
        for d in wanted:
            sanedeps = sanedeps.intersection(set(crazydepends[d]))
        fodepends |= sanedeps
    packs = " ".join(fodepends)
    cmd = f"apt-rdepends {packs} 2> /dev/null | grep -v Depends"
    deps = getpipeoutput([cmd], quiet=True).split("\n")
    newdeps = set(deps) & set(vertexes)
    return list(newdeps)

def main(args):
    implied = set(build_graph(args))
    print(" ".join([x for x in args if x not in implied]))

if __name__ == "__main__":
    main(sys.argv[1:])