xmodmap -version (return code: 0)
xmodmap 1.0.9
xmodmap -h (return code: 0)
usage: xmodmap [-options ...] [filename]
where options include:
-display host:dpy X server to use
-verbose, -quiet turn logging on or off
-n don't execute changes, just show like make
-e expression execute string
-pm print modifier map
-pk print keymap table
-pke print keymap table as expressions
-pp print pointer map
-help print this usage message
-grammar print out short help on allowable input
-version print program version
- read standard input