Checks for invalid/obsolete entries in Gentoo Portage's package.use files

check-use

#!/bin/bash
#
# Author: Gary Macindoe
# Date: May 2013

files="/etc/portage/package.use"
if [ -d "${files}" ]
  then
  files="${files}/*"
fi

for file in ${files}
  do
  echo -e "\E[1;33;40m${file}:"
  grep -Ev '^[ \t]*#|^$' ${file} | while read atom uses
    do
    packages="$(equery -q l ${atom} 2>/dev/null)"
    if [ $? -ne 0 ]
      then
      echo -e "\E[0;31;40mNo package installed matching ${atom}"
    fi
    package_uses=""
    skip=2
    for package in ${packages}
      do
      package_use="$(equery -q u ${package} 2>/dev/null)"
      if [ $? -ne 0 ]
        then
        echo -e "\E[0;31;40mUnable to find use flags for ${package} (most likely the ebuild has been removed)"
        if [ ${skip} -ne 0 ]
          then
          skip=1
        fi
      else
        package_uses="${package_uses} $(echo ${package_use} | sed -e's/^-\|+//g')"
        skip=0
      fi
    done
    if [ ${skip} -eq 0 ]
      then
      echo -ne "  \E[0;36;40m$(echo ${atom} | cut -d'/' -f1)/\E[0;32;40m$(echo ${atom} | cut -d'/' -f2)"
      for use in ${uses}
        do
        if [ ! "$(echo ${package_uses} | grep -- $(echo ${use} | sed -e's/^-\|+//g'))" ]
          then
          if [ "$(echo ${use} | cut -c1)" = "-" ]
            then
            echo -ne " \E[1;34;40m${use}"
          else
            echo -ne " \E[1;31;40m${use}"
          fi
        fi
      done
      echo
    fi
  done
done

if [ -e "/etc/portage/make.conf" ]
  then
  file="/etc/portage/make.conf"
else
  file="/etc/make.conf"
fi

if [ -e "${file}" ]
  then
  echo -e "\E[1;33;40m${file}:"
  uses="$(grep ^USE= ${file} | cut -d'"' -f2)"
  for use in ${uses}
    do
    u=$(echo ${use} | sed -e's/^-\|+//g')
    equery -q h ${u} &>/dev/null
    if [ $? -ne 0 ]
      then
      if [ "$(echo ${use} | cut -c1)" = "-" ]
        then
        echo -ne " \E[1;34;40m${use}"
      else
        echo -ne " \E[1;31;40m${use}"
      fi
    fi
  done
fi
echo -e "\E[0m"