#action

Trigger action X from thing Y.

For example, bind the F11 key to action -t f11 (-t for trigger) in your favorite window manager and run (-b for bind):

while action -b f11; do screenshot; done

in your favorite terminal emulator when you're working with something you want to screenshot. Note that the f11 string is arbitrary, i.e. go crazy, what about volume_up, fix_wifi, call_mom?