xdotool - fake keyboard/mouse input

This tool lets you programatically (or manually) simulate keyboard input and
mouse activity, move and resize windows, etc. It does this using X11's XTEST
extension and other Xlib functions.

Example: focus the firefox url bar

WID=`xdotool search "Mozilla Firefox" | head -1`
xdotool windowfocus $WID
xdotool key ctrl+l