PWB1/root/bin/diff3

= p /bin:/usr/bin
onintr intr
goto start
: intr
	rm -f /tmp/d3a$$ /tmp/d3b$$ >/dev/null
	exit 1

: start
	= a ""
	while 1
		expr substr "$1" 1 1 | = b
		if "x$b" = "x-" then
			= a "$a $1"
			shift
		else
			break
		endif
	end
	if "x$3" = "x" -o "x$4" != "x" then
		echo "Usage: diff3 [-...] file1 file2 file3"
		exit 1
		endif
	if ! -r "$1" then
		echo "Can't open $1"
		exit 1
		endif
	if ! -r "$2" then
		echo "Can't open $2"
		exit 1
		endif
	if ! -r "$3" then
		echo "Can't open $3"
		exit 1
		endif
	diff $1 $3 >/tmp/d3a$$
	diff $2 $3 >/tmp/d3b$$
	/usr/lib/diff31 $a /tmp/d3a$$ /tmp/d3b$$ $1 $2 $3
	rm -f /tmp/d3a$$ /tmp/d3b$$ >/dev/null