#!/bin/bash -x

OUTPUTPREFIX="/raid/backup/backup-$(hostname)-$(date +%F).cpio.gz."

mkdir -p "$(dirname "$OUTPUTPREFIX")"

time comm -23 <(
      # All files on /, less a few stupid paths.  We want to back up most of these.
      find / -xdev \
               -wholename /usr/portage                  -prune \
            -o -wholename /tmp                          -prune \
            -o -wholename /var/tmp                      -prune \
            -o -wholename /usr/src                      -prune \
            -o -wholename /home/chkno/linux             -prune \
            -o -wholename /home/chkno/media             -prune \
            -o -wholename /home/bulk/.mldonkey/incoming -prune \
            -o -wholename /home/bulk/.mldonkey/temp     -prune \
            -o -wholename /lib/modules                  -prune \
            -o -wholename /var/cache/edb                -prune \
            -o -wholename /var/cache/squid              -prune \
            -o -wholename /media                        -prune \
            -o -name .ccache                            -prune \
            -o -name '*.py[co]'                                \
            -o -print                                          |
         sort
   ) <( 
      # All non-modified portage-mannaged files

      # Ideally:
      # equery files --filter=obj,-mod '=*'

      comm -23 <(
            # All files managed by portage.  We DONT want most of these.
            equery list                |
               sed 's/^/=/'            |
               xargs -n 1 equery files |
               sort
         ) <(
            # Modified files.  We DO want most of these.
            equery list                                        |
               sed 's/^/=/'                                    |
               xargs -n 1 equery check 2>&1                    |
               sed -n 's/!!! \(.*\) has incorrect md5sum/\1/p' |
               sort
         )
   )               |
   cpio -o -H newc |
   gzip -v --best  | 
   split -b $((128*1024*1024)) --verbose - "$OUTPUTPREFIX"