T=`mktemp -d ${TMPDIR:-/tmp}/sh-test.XXXXXXXX`
trap 'rm -rf "$T"' 0
cd "$T" || exit 3
mkfifo fifo1 || exit 3
set -T
trap "for i in 1 2 3 4; do sleep 1 & done" USR1
sleep 1 &
{ kill -USR1 "$$"; echo .; } >fifo1 &
(read dummy <fifo1)