使用 pip 从存储库安装软件包时，(s)witch、(i)gnore、(w)ipe、(b)ackup 选项是什么意思？

Question

When installing a package using pip, I get the following message:

Obtaining some-package from git+git://github.com/some-user/some-package.git@commit-hash#egg=some_package-dev (from -r requirements.txt
 (line 3))
  git clone in /Users/me/Development/some-env/src/some-package exists with
 URL https://github.com/some-user/some-package.git
  The plan is to install the git repository git://github.com/some-user/some-package.git
What to do?  (s)witch, (i)gnore, (w)ipe, (b)ackup

I see that this particular case is probably caused by a change of protocol in URL (new requirement uses git:// , while the one already installed uses https:// ).

However, I wonder what exactly happens if I choose either of the choices (switch, ignore, wipe, backup). I'm unable to find an explanation in pip documentation.

Answer 1

A patch explaining this option was merged into the PIP documentation, but it was not released until Pip 6.0 (2014-12-22). ( https://github.com/pypa/pip/commit/b5e54fc61c06268c131f1fad3bb4471e8c37bb25 ). Here is what that patch says:

--exists-action option

This option specifies default behavior when path already exists. Possible cases: downloading files or checking out repositories for installation, creating archives. If --exists-action is not defined, pip will prompt when decision is needed.

• (s)witch

  Only relevant to VCS checkout. Attempt to switch the checkout to the appropriate url and/or revision.

• (i)gnore

  Abort current operation (eg don't copy file, don't create archive, don't modify a checkout).

• (w)ipe

  Delete the file or VCS checkout before trying to create, download, or checkout a new one.

• (b)ackup

  Rename the file or checkout to {name}{'.bak' * n} , where n is some number of .bak extensions, such that the file didn't exist at some point. So the most recent backup will be the one with the largest number after .bak .

And here is a link to description of that option in the now-updated documentation: https://pip.pypa.io/en/stable/cli/pip/#exists-action-option .