if $1x = x then
	echo 'Usage: spell file ...'
	exit
endif
while $1
	if ! -r $1 then
		echo "Can't find $1"
		shift
		continue
	endif
	deroff < $1 ^ tr "[A-Z]" "[a-z]" ^ sort -u > /tmp/sp$$$
	comm -23 /tmp/sp$$$ /usr/lib/w2006 > $1.doubt
	rm /tmp/sp$$$
	if -r $1.words then
		mv $1.doubt temp$$$
		comm -23 temp$$$ $1.words > $1.doubt
		rm temp$$$
	endif
	echo "doubtful words in $1 can be found in $1.doubt"
	shift
end
