I think I did that.
I am using Mint flavor of Ubuntu, some ubuntu instructions fail.
I tried this.
That sources.list was empty before I added that line in.
And when I went to complete the update, I got a long list of successful stuff but ended like this:
universe Translation-en_US
Fetched 379 kB in 4s (76.5 kB/s)
Reading package lists... Done
W: GPG error:
http://ftp.de.debian.org experimental InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 8B48AD6246925553
W: Ignoring Provides line with DepCompareOp for package php-psr-log-implementation
E: Could not open lock file /var/lib/dpkg/lock - open (13: Permission denied)
E: Unable to lock the administration directory (/var/lib/dpkg/), are you root?
I am hoping for a binary that I can download, as I am not so experienced in Linux.
I was doing this as sudo, but not at root. Should I have been sudo su?
Update: It worked as sudo su.
All is well.