there might be no lines which contain this flag Again, untested: #! /bin/sh timeout=5 fifo=/tmp/discover-vnc.fifo rm -f $fifo

there might be no lines which contain this flag Again, untested: #! /bin/sh timeout=5 fifo=/tmp/discover-vnc.fifo rm -f $fifo mkfifo $fifo dns-sd -B _rfb._tcp >$fifo & pid1=$! while read line; do case $line in *_rfb._tcp.*) # do something here.. then test # if flag=3 and break otherwise esac done <$fifo & pid2=$! sleep $timeout && kill $pid1 $pid2 & pid3=$! wait $pid2 kill $pid3 It's also rather ugly to create a named pipe for this purpose Because it creates a file in /tmp? Who cares? The alternative is bash voodoo magic.. the same magic that gave us shellshock.