ref: 7bfd5b6e701b9a7c2b9d772820f66cacadc0ded9
dir: /sys/src/libc/port/reduce/
O=$1
shift
objtype=$1
shift
ls -p ../$objtype/*.[cs] >[2]/dev/null | sed 's/..$//;s/^/^/' > /tmp/reduce.$pid
#
# if empty directory, just return the input files
#
if (! ~ $status '|') {
echo $*
rm /tmp/reduce.$pid
exit 0
}
echo $* | tr ' ' \012 | grep -v -f /tmp/reduce.$pid | tr \012 ' '
rm /tmp/reduce.$pid