USG_PG3/usr/bin/diff3

if ! "(" $1 = -e -o $1 = -x -o $1 = -3 ")" goto diff
= e $1
shift
: diff
diff $1 $3 >d3$$1
diff $2 $3 >d3$$2
/usr/lib/diff3 $e d3$$1 d3$$2 $1 $2 $3
rm d3$$1 d3$$2