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    <p>The problem you have is that you cannot wait for one of multiple background processes to complete. If you observe job status (using jobs) then finished background jobs are removed from the job list. You need another mechanism to determine whether a background job has finished.</p> <p>The following example uses starts to background processes (sleeps). It then loops using ps to see if they are still running. If not it uses wait to gather the exit code and starts a new background process.</p> <pre><code>#!/bin/bash sleep 3 &amp; pid1=$! sleep 6 &amp; pid2=$! while ( true ) do running1=`ps -p $pid1 --no-headers | wc -l` if [ $running1 == 0 ] then wait $pid1 echo process 1 finished with exit code $? sleep 3 &amp; pid1=$! else echo process 1 running fi running2=`ps -p $pid2 --no-headers | wc -l` if [ $running2 == 0 ] then wait $pid2 echo process 2 finished with exit code $? sleep 6 &amp; pid2=$! else echo process 2 running fi sleep 1 done </code></pre> <p>Edit: Using SIGCHLD (without polling):</p> <pre><code>#!/bin/bash set -bm trap 'ChildFinished' SIGCHLD function ChildFinished() { running1=`ps -p $pid1 --no-headers | wc -l` if [ $running1 == 0 ] then wait $pid1 echo process 1 finished with exit code $? sleep 3 &amp; pid1=$! else echo process 1 running fi running2=`ps -p $pid2 --no-headers | wc -l` if [ $running2 == 0 ] then wait $pid2 echo process 2 finished with exit code $? sleep 6 &amp; pid2=$! else echo process 2 running fi sleep 1 } sleep 3 &amp; pid1=$! sleep 6 &amp; pid2=$! sleep 1000d </code></pre>
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    1. PORun bash commands in parallel, track results and count
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    1. COCan this be done without the polling somehow? If I consume one processor just with BASH part of the value in running in parallel is somewhat lost.
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    2. COYes, using `trap SIGCHLD`. See my edit to my answer.
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    3. COProblem here is that ChildFinished could be called before you manage to set `pid1`. Obviously not with `sleep 3` but some random process could exit quickly (particularly if it has an error at startup)
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