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So I have a small script that I run as source (for those interested, I do this so that I can attain the correct $SECONDS value of the person running the script), as well as place the program in the background. Inside of this script there is an infinite loop that runs to update a temp file every second.

So my question, how do I attain the PID of the loop inside the script that needs to be terminated to kill the updating of the temp file/the script?

  • In the second script, record the PID of the background process in a variable (e.g., pid=$!). Since you're using source, the variable will be visible in the first script. – larsks Aug 3 '16 at 23:39
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  1. If you source it, it's not really a separate script. It is as if you had all those lines you source present in the place/script you source/call it from.

  2. A loop doesn't have a PID. If it's in the foreground, it works under the current PID. But if you send it to the background, then the job get's it's own PID, which you can attain this way:

    do-something-in-a-loop & pid=$!

  3. You can also use the job spec of the task if you know it. If you have only 1 job, you can do kill %1.

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The short answer is that the loop doesn't have its own PID since it doesn't run in a separate process, i.e. the PID of the loop is the PID of the script.

For a more useful answer, post actual code.

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