check for GTFS update automatically

[osm-ToniE]

check periodically all GTFS-feeds for updates.
Do this in dedicated shell-scripts which may also do the download on demand (manually)

Example:

curl -sI https://www.vag-freiburg.de/fileadmin/gtfs/VAGFR.zip | grep "last-modified" | sed -e s/last-modified:\ // | date +"%Y-%m-%d" -f -

Of course, this is an easy example, the link to the source is always the same.

maybe create an empty DB (if DB does not exist already) indicating that updates are available at the owner

[osm-ToniE]

Done via three scripts

• get_release_date.sh which prints out the date of the latest GTFS feed

• get_release_url which prints out the URL to retrieve the latest GTFS feed

• cleanup.sh which deletes temporary files

These shell scripts will be used bei 'gtfs-feed.sh' in the 'gtfs' repository