20170107: It's not "group name" it's "Group ID." I don't know how to find that yet.
The communications program Signal by Open Whisper Systems is unique in several respects. Firstly, its barrier to entry is minimal. You can search for it in the Google Play online store or Apple iOS appstore and it's waiting there for you at no cost. Second, it's designed for security by default, i.e., you don't have to mess around with it to make it work, and it does does the right thing automatically and enforces strong encryption by default (unlike a lot of personal security software). It interoperates seamlessly with people who don't use Signal but you have the option to invite them to install it with a single tap. Its protocol is an open standard that multiple companies have implemented, so theoretically anyone can write their own implementation of the client (Android, iOS) or server, or compile it for themselves. It's an SMS/MMS application, so you can use it as your default text messaging client on your mobile, plus it can do text message conferencing with multiple people automatically (it's a great way to keep in touch with friends if you're at the same con). There's even a desktop Signal client that runs inside of Google Chrome or Chromium (source code for the interested and curious).
So, why, exactly am I posting about Signal?
There is a little-known command-line implementation of Signal that I've been experimenting with because I eventually plan on writing a bot for my exocortex. In playing around with it, I've come to realize that it's not particularly friendly to use at all, and I might have to break down and use the dbus interface to do anything useful with it. Which I don't look forward to, but that's not the point. The point is, I've compiled some notes about how to use the command line version of Signal and I wanted to put them online in case somebody will find them helpful.