How to reinstall a pip package even if it exists

Question

I want to run a pip install -r requirements.txt command;

I want to run the same command over and over again;

The issue is that requirement

Answer 1

With --force-reinstall, existing packages (and dependencies) are uninstalled first, while with --ignore-installed, they are not.

So --force-reinstall is the preferred choice and --ignore-installed is more of an emergency option.

Here's a sample output:

> pip install --force-reinstall ipdb
Collecting ipdb
Collecting ipython<6.0.0,>=5.0.0; python_version == "2.7" (from ipdb)
  Using cached https://<...>/ipython-5.8.0-py2-none-any.whl
Collecting setuptools (from ipdb)
<...>
Installing collected packages: six, wcwidth, prompt-toolkit, decorator, setuptools, <...>
  Found existing installation: six 1.11.0
    Uninstalling six-1.11.0:
      Successfully uninstalled six-1.11.0
  Found existing installation: wcwidth 0.1.7
    Uninstalling wcwidth-0.1.7:
      Successfully uninstalled wcwidth-0.1.7
<...>
Successfully installed backports.shutil-get-terminal-size-1.0.0 colorama-0.4.0 <...>


> pip install --ignore-installed ipdb
Collecting ipdb
Collecting ipython<6.0.0,>=5.0.0; python_version == "2.7" (from ipdb)
<...>
Collecting setuptools (from ipdb)
<...>
Installing collected packages: six, wcwidth, prompt-toolkit, decorator, setuptools, <...>
Successfully installed <...>