How to timeout a Bash command and count the number of lines emitted to stdout?

Question

I'd like to do something like timeout 12s tail -f access.log | wc -l but I'm not seeing the output from wc. What needs to be done to be able to do this?

anubhava · Accepted Answer · 2017-04-28 20:55:16Z

5

Use --foreground option with timeout:

timeout --foreground 12s tail -f access.log | wc -l

As per man timeout:

--foreground   when not running timeout directly from a shell prompt,
               allow COMMAND to read from the TTY and get TTY signals;
               in this mode, children of COMMAND will not be timed out

answered Apr 28, 2017 at 20:55

anubhava

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Noel Yap Over a year ago

Be sure to wait long enough when initially trying this out. For example, I had first started using timeout --foreground 1s but the command took much longer than 1 second to return presumably because of the large volume that needed to be processed.

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