know when a asynchronous process is done

[Xah Lee]

How can i know a asynchronous process (started by my elisp) is done?

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detail:

i want to write a elisp program so that it runs a shell command to
render a pov-ray file. I want the process to run in the background,
but when it is done, open the generated image.

My problem is that i don't know how to code that knows when a
asynchronous process is done.

Thanks in advance.

  Xah
  xah@xahlee.org
∑ http://xahlee.org/

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