We don't need these backed up, and having them in the list leads to
an error due to not having show_compatibility_56 enabled

Resolves #3

changed maintainer
mention name of git repository since it doesn't match package name

We now e.g. have a cron job on cerebro-backup which calls
these scripts, where /sbin is not on the $PATH.

For cerebro-backup where we do backups by the directory rather than the
whole server. We need to have one machine being backed up
(cerebro-filestore) but a task per directory.

The new-backup-rsnapshot script understands a 'postgres' argument, but
this set up a postgres backup in an old style that we no longer use.
This change updates it to do some of the work of setting up a new style
postgres backup and tell the user what else they might need to edit to
make it go; it varies quite a lot depending on server.

Let's not worry if we haven't backed up a machine that has been offline for 3 months (instead of 6 months)

Our backup logs are generally full of

+ ssh -p 22 -o ConnectTimeout=10 root@openvpn2020.ch.cam.ac.uk '
  umask 077
  FILELIST=`tempfile`
  CONFLIST=`tempfile`
  mkdir -p /var/adm/backup
  # Make logrotate use datestamps
  if ! grep -q dateext /etc/logrotate.conf ; then sed  -i '\''s/^include/dateext\ninclude/'\'' /etc/logrotate.conf ; fi
  # Which packages are installed?
  dpkg --get-selections | awk '\'' { print $1 ; } '\'' >/var/adm/backup/packages
  cat /var/lib/dpkg/info/*.list | while read F ; do [ -f "$F" ] && echo "$F" ; done | sort > $FILELIST
  awk '\''/Description:/ { flag = 0 } ; flag == 1 { print $1 ; }  ; /Conffiles:/ { flag = 1  } ; '\'' </var/lib/dpkg/status |  sort >$CONFLIST
  diff -u $FILELIST $CONFLIST | grep ^-/ | sed s/^-// >/var/adm/backup/package-files
  rm
 '
rm: missing operand

because we're not escaping the args to that final rm command! This means we gradually fill
up /tmp, especially on machines that are infrequently rebooted (e.g. calculon)

Previously just depended on 'postgres' which was OK until we switched to
using the Postgres provided repository for postgres packages, which
makes postgres be postgres 10. Haven't tested any of the infrastructure
for 10 and don't want to start right now.

prepare-olddebian : does not do package file excludes
prepare-database: does not do package file excludes or dump databases

These are for use on machines where we can no longer reinstate them by
quickly and easily installing a new VM from the network and then
layering the backup on top, usually because the OS is obsolete.

This seems to be used for machines with postgres. It was also updated
to put exclude and log files in the new locations.

debian-zfs doesn't exist in Ubuntu.