From the documentation for subprocess

It is a drop in replacement with better behavior in many situations.

I don't understand the drop meaning in the paragraph. who can explain it for me?

  • Maybe, a technical jargon!
    – Maulik V
    Commented Sep 19, 2017 at 2:51

1 Answer 1


The trick here is that drop in is slightly mis-punctuated, and drop does not stand on its own. The software is not a "drop (in replacement)" but rather a "(drop-in) replacement."

It is a replacement. What type of replacement? A drop-in replacement.

Drop-in as an adjective can mean several things. Definition #4 at Dictionary.com is close in meaning to how it is being used here:

drop-in - requiring only insertion to be ready for use:>

If two pieces of software perform more or less the same task, but go about it with different approaches, interface and/or APIs, then one is a replacement for the other, but neither is a drop-in replacement for the other. Think Outlook and Gmail. Both serve essentially the same purpose, but they accomplish it very differently.

By contrast, mpg123 and mpg321 do the same thing, are about the same size, and take almost identical command line arguments. mpg321 is a drop-in replacement for mpg123

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