Using pip from your program: wrong command

[ghost]

In the documentation, there is a mistake in the subprocess command at the bottom of the page.

https://pip.pypa.io/en/stable/user_guide/#using-pip-from-your-program

The first command is: subprocess.check_call([sys.executable, '-m', 'pip', 'install', 'my_package']) which works fine.

But the second is: reqs = subprocess.check_output([sys.executable, '-m', 'pip', 'freeze'])
And should be: reqs = subprocess.check_output([sys.executable, '-m', 'pip', 'install', 'freeze'])

[pfmoore]

Why? That would run pip install freeze which is installing a package freeze, whereas the current code runs pip freeze which is something you'd want to capture the output from, and so is a better example...

[pradyunsg]

Hey there @Drugong! Thanks for filing this issue.

pip has multiple commands (like install) and freeze is one such command. We have a reference list of pip's commands at https://pip.pypa.io/en/latest/reference/.

I think your suggestion stems from an understanding that pip does not have a freeze command, but as @pfmoore pointed out, it does. :)

[chrahunt]

I think the way it is currently worded one might expect the same command to be used in both examples. We might expand on the text to indicate that we did actually mean to put freeze there for the reason @pfmoore stated.

[deveshks]

Hi @chrahunt

I think we can change the current text which says

If you want to process the output further, use one of the other APIs in the module:

to

If you want to process the output further, use one of the other APIs in the module. We are using https://pip.pypa.io/en/latest/reference/pip_freeze/ here which outputs installed packages in requirements format.

If that change is something what you meant if your comment above, I can create a PR for the same.

[pfmoore]

That sounds like a reasonable clarification to add.

[deveshks]

Thanks @pfmoore for your comment. I have added a PR to add this explanation