syndaemon(1) -i 1 -K -R -d
a program that monitors keyboard activity and disables the touchpad when the keyboard is being used
-i <idle-time>
       How  many  seconds  to  wait  after  the last key press before enabling the touchpad.  (default is
-K     Like -k but also ignore Modifier+Key combos.
-R     Use the XRecord extension for detecting keyboard activity instead of polling the keyboard state.
-d     Start as a daemon, ie in the background.
source manpages: syndaemon