If you just need "switch using keyboard", not necessarily "switch using shell", some KVM switches allow input switching using keypresses. For mine, it's <SROLLLOCK> <SCROLLOCK> <1-4> <ENTER>, though I think that can be customized.
Well, what I actually want to do is switch via my DIY macropad. My keyboard switch goes through that, without relying on any of the main computers. I had a cheap HDMI switch that worked the same way, but it just stopped working reliably after a month.
I sometimes want independent control of the keyboard switch and the monitor switch, so I'm not sure if a KVM is the best option for me.
