Question

I have an interesting situation I am trying to script. I have a program that outputs 26,000 lines after 10 seconds when it starts successfully. Otherwise I have to kill it and start it again. I tried doing something like this:

test $(./long_program | wc -l) -eq 26000 && echo "Started successfully"

but that only works if the program finishes running. Is there a clever way to watch the output stream of a command and make decisions accordingly? I’m at a loss, not quite sure even how to start searching for this. Thanks!

Answer 1

What about

./long_program > mylogfile &
pid=$!
sleep 10

# then test on mylogfile length and kill $pid if needed