I am stuck in a course about computer algebra systems. We are using Singular. I searched for some minutes how to switch on the vi mode on the Singular command line, but apparently, there is none.
However, since Singular uses the GNU readline libs, you can simply switch to vi mode with Ctrl-Meta-j. – How convenient is that. I wonder if there's a possibility to configure readline to switch to vi mode by default.
Update 2015-03-25: Markus informs me that to enable
Vi mode by default, write the line set editing-mode vi into your ~/.inputrc
(or the global /etc/inputrc).