I made a tiny utility to be able to adjust sound, brightness, gamma etc., from the terminal.

In the file ~/.adjustments, just add a name for the thing you want to control, then low high step and initial values, can be decimal, and then a line with the command you want to execute, with a single '%' being replaced with the value.

Hit 'q' to finish.

It's super handy to have ← → cursor keys to adjust a setting, rather than retyping the command in full.