linux bash script running multiple python

Question

I have 2 python scripts a.py and b.py and I want to write a bash script that will load a.py and not run b.py until a.py is done doing it's thing. simplistically

#!/usr/bin/env bash
python a.py
python b.py

but this is naive, a check to see if a.py is done... how do I do that?

Answer 1

This by default will already run one after the other.

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To check that python a.py completed successfully as a required condition for running python b.py, you can do:

#!/usr/bin/env bash
python a.py && python b.py

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Conversely, attempt to run python a.py, and ONLY run 'python b.py' if python a.py did not terminate successfully:

#!/usr/bin/env bash
python a.py || python b.py

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To run them at the same time as background processes:

#!/usr/bin/env bash
python a.py &
python b.py &

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(Responding to comment) - You can chain this for several commands in a row, for example:

python a.py && python b.py && python c.py && python d.py