Hi,
thanks for your comment.

The sed pipe was not correctly displayed because this blog software does not transform to HTML entities automatically -- I corrected it.

With the variable $tmpfile you where right, I also corrected it. I am wondering why it worked without the $ sign?

You're right that the mktemp command does not clean up automatically but therefor I do a rm at the end of the script.

Kannte ich noch gar nicht. Vielen Dank für den Hinweis :-)

Do you mean damaging by falling of the bike? I will protect it with an additional rubberband.