I had this running perfectly and the blockchain was synching and at about 80% completion. I came home from work to a power outage.
I keep seeing to run bitcoin-qt, it doesn't appear that I have that. In /src/ I have bitcoin-cli, bitcoind, and bitcoin-tx. Obviously d is daemon, and -tx isn't what I want either. So I try
bitcoin-cli -datadir=/pi/home/bitcoin/ error: too few parameters (need at least command)
It seems like you simply haven't installed bitcoin-qt, if you install that then you can run it :)
I'm unsure exactly how the power outage and the datadir command at the end relate to the question though
Yes, the gui is bitcoin-qt - just copy it back in from the download if it is missing. Also, if you used the install command, have a look if it is in /usr/local/bin or similar, it should just run from the command line.
Have you followed the build instructions?
They are found here: https://github.com/bitcoin/bitcoin/blob/master/doc/build-unix.md
Make sure that you have installed all the related GUI dependences or else you will not have bitcoin-qt on your machine.
Also, bitcoin-cli is a command line tool to speak with your bitcoin node (bitcoind). You need to pass a command. The data-dir flag is just specifies a data directory. Try passing a command like getblockchaininfo
