running multiple commands in parallel in bash

Question

I want to run multiple scripts/commands in parallel in bash. Here is the bash script :

python test_script.py &
docker stop process &
docker stop process1 &
sleep(1)
wait

docker start process1 &
docker start process &
wait

Here, im running multiple dockers and want to start/stop docker when my script python test_script.py is running.

for ex: python script is running and on parallel i want to stop process & process1 docker. python script is still in-progress and then say wait or sleep for 1 min and start the process again.

How can i achieve it ?

Does this answer your question? [How do you run multiple programs in parallel from a bash script?](https://stackoverflow.com/questions/3004811/how-do-you-run-multiple-programs-in-parallel-from-a-bash-script) — Michael Freidgeim, Oct 30 '20 at 12:36

score 1 · Answer 1 · answered Nov 17 '17 at 09:36

1

You can combine the following rules:

X; Y Run X and then Y, regardless of success of X

X && Y Run Y if X succeeded

X || Y Run Y if X failed

X & Run X in background.

answered Nov 17 '17 at 09:36

Alex Dragnea

174
1
6

Thanks Alex for answering. I'm looking to run these commands in parallel in script. In the mentioned bash script python test-script is running and then in parallel after some seconds i want to start/stop docker images. – Pooja Nov 17 '17 at 10:07

score 1 · Answer 2 · answered Nov 17 '17 at 11:57

1

From your original description, it seems that we can organize the problem into two scripts

A main python script test_script.py
A docker restart script say restart_docker.sh which contains all the docker related commands that will be executed in sequence
```
docker stop process
sleep 1m
docker start process
```

With GNU parallel, you can provide these two scripts as arguments to be executed in parallel

parallel ::: 'python test_script.py' 'bash restart_docker.sh'

answered Nov 17 '17 at 11:57

etopylight

1,239
1
10
15

Thanks, this helped. But the output of test_script.py is not getting listed in the console / CLI. Is there a way to display the script execution output with parallel command ? – Pooja Nov 19 '17 at 13:04
What is the difference between executing the above shared command by you and parallel 'python test_script.py' ::: 'bash restart_docker.sh' – Pooja Nov 19 '17 at 13:10
@Pooja Hmm that's odd, `parallel` should forward all the messages generated from each command to stdout, maybe you accidentally added a `&`? – etopylight Nov 19 '17 at 14:05
@Pooja For the detail usage of the `parallel` syntax, you can always refer to its manual page. In short, by using `parallel ::: A B`, this means that A and B will run as separate commands while `parallel A ::: B` means that A is a command and B is an argument for A – etopylight Nov 19 '17 at 14:05

running multiple commands in parallel in bash

2 Answers2