He told me that he had a temperature measuring device, that he could not find, back in 2011
He needed something like a data logger. Easy and light, cheap, with a battery lasting over year or so, that he could install at customers' places in order to have a Log of "what happened" if any problem came up.
Say, a frozen (broken) pipe or other malfunctions in heating, AC and such. He said connectivity wasn't necessary and to log to a SD-card that could be inspected later would be sufficient.

Vor ein paar Tagen ist mein zweiter „Ledger Nano S“ – eines der Besten Hardware-Wallets zum jetzigen Zeitpunkt – im Postfach gelandet. 

In zwei Videos zeige ich euch das „Unboxing“ vom Schlüssel und eine Einführung in die Bedienung des Selbigen.

Am "einfachsten" und "schönsten" geht das Verteilen eine PUBLIC Key via Key-server. Bei Mailvelope kann man einen bevorzugten Key-server in den Einstellungen angeben und vordefiniert steht dort der Key-server von "ubuntu.com".

I always get very defensive when I hear or read that expression. "The stack" has grown much larger over the years - I've been building software since 1997 - and when someone claims to have mastered knowledge in all layers of "the stack" is no small claim.

Does that mean you have a large amount of knowledge, or are you specialized in every discipline?