postinst is in libreoffice-core 1:3.5.7-0ubuntu13.
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 | #!/bin/sh
set -e
PLATFORMID=linux_x86_64
validate_extensions() {
	/usr/lib/libreoffice/program/unopkg validate -v --shared
}
sync_extensions() {
  INSTDIR=`mktemp -d`
  export PYTHONPATH="/usr/lib/libreoffice/program"
  if [ -L /usr/lib/libreoffice/basis-link ]; then
	d=/var/lib/libreoffice/`readlink /usr/lib/libreoffice/basis-link`/
  else
	d=/usr/lib/libreoffice
  fi
  if [ -e /usr/lib/libreoffice/share/prereg/bundled ] && readlink /usr/lib/libreoffice/share/prereg/bundled 2>&1 >/dev/null && [ -e /usr/lib/libreoffice/program/unopkg.bin ]; then
    /usr/lib/libreoffice/program/unopkg sync -v --shared \
      "-env:BUNDLED_EXTENSIONS_USER=file:///usr/lib/libreoffice/share/prereg/bundled" \
      "-env:UserInstallation=file://$INSTDIR" \
      "-env:UNO_JAVA_JFW_INSTALL_DATA=file://$d/share/config/javasettingsunopkginstall.xml" \
      "-env:JFW_PLUGIN_DO_NOT_CHECK_ACCESSIBILITY=1"
  fi
}
if [ "$1" = "triggered" ]; then
	for triggername in $2; do
		case "$triggername" in
			# new "bundled" extensions (since 3.3)
			"/usr/lib/libreoffice/share/extensions")
			  sync_extensions
			;;
		esac
	done
fi
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