Can a bash script run simultaneous commands then wait for them to complete?

Question

I want to write a bash script where I run two commands simultaneously, then continue when they both complete.

Here's something that doesn't work, but I'll put it here to illustrate what I'm trying to do:

#!/bin/bash
./job1 &
./job2
./dostuffwithresults

The script will run both job1 and job2 at the same time, but will only wait for job2 to finish before continuing. If job1 takes longer, then the results might not be ready for the final command.

score 64 · Accepted Answer · answered Jan 24 '12 at 20:31

64

j1 &
j2 &
j3 &
wait $(jobs -p)
dostuffwithresults

answered Jan 24 '12 at 20:31

Michael Krelin - hacker

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11

+1, but the argument to wait is not required in this case as it's the default. – Johan Lundberg Jan 25 '12 at 10:35
@JohanLundberg, indeed, I had no idea ;-) – Michael Krelin - hacker Jan 25 '12 at 18:17
2

Reason to add the argument to wait is if you wish to collect status from the jobs. Unfortunately, only returns the status of the last process in list, so would have to iterate to check/gather all status' – libjack Oct 21 '14 at 22:13
some explanation how and why this works would be great – Xanlantos Aug 08 '19 at 07:26

score 1 · Answer 2 · answered Jan 24 '12 at 20:40

1

something like this should work

    #!/bin/bash
    while [ `pgrep job*` ]
    do 
    echo 'waiting'
    done

    ./dostuffwithresults

answered Jan 24 '12 at 20:40

Harry Forbess

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Can a bash script run simultaneous commands then wait for them to complete?

2 Answers2

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