postinst is in gup 0.5.15build1.
This file is a maintainer script. It is executed when installing (*inst) or removing (*rm) the package.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48  | #!/bin/sh -e
create_uid_and_files() {
if ! getent passwd gup >/dev/null; then
  adduser --system --home /var/lib/gup/ --ingroup news \
    --disabled-password --gecos "Group Update Program" gup
elif [ ! -d /var/lib/gup/ ]; then
  mkdir /var/lib/gup/
  chown gup:news /var/lib/gup/
fi
if [ ! -d /var/lib/gup/default ]; then
  cd /var/lib/gup/
  echo '| /usr/lib/gup/process' > .forward
  ln -s /etc/gup.conf config
  mkdir default sites
  printf 'HOST\\\n  :!*,\\\n' > default/header
  echo '  :Tf,Wfb,B4096/1024:' > default/trailer
  ln -s /etc/news/newsfeeds.header default/global.header
  chown --recursive gup:news .
fi
if [ ! -f /etc/gup.conf ]; then
  printf '#site\tpassword\tuser@example.com\n' > /etc/gup.conf
  chown gup:news /etc/gup.conf
  chmod 700 /etc/gup.conf
fi
if [ ! -d /var/log/gup ]; then
  install --directory --owner=gup /var/log/gup
fi
}
case "$1" in
    configure)
    create_uid_and_files
    ;;
    abort-upgrade|abort-remove|abort-deconfigure)
    ;;
    *)
    echo "postinst called with unknown argument '$1'" >&2
    exit 1
esac
	    
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