I’ve been usually installed python packages through pip.

For Google App Engine, I need to install packages to another target directory.

I’ve tried:

pip install -I flask-restful –target ./lib

but it fails with:

must supply either home or prefix/exec-prefix — not both

How can I get this to work?

Are you using OS X and Homebrew? The Homebrew python page https://github.com/Homebrew/brew/blob/master/docs/Homebrew-and-Python.md calls out a known issue with pip and a work around.

Worked for me.

You can make this “empty prefix” the default by adding a ~/.pydistutils.cfg file with the following contents:

[install]
prefix=

Edit: Do not use this Homebrew recommended option, it will break normal pip operations.

I believe there is a simpler solution to this problem (Homebrew’s Python on macOS) that won’t break your normal pip operations.

All you have to do is to create a setup.cfg file at the root directory of your project, usually where your main __init__.py or executable py file is. So if the root folder of your project is: /path/to/my/project/, create a setup.cfg file in there and put the magic words inside:

[install]
prefix=  

OK, now you sould be able to run pip’s commands for that folder:

pip install package -t /path/to/my/project/  

This command will run gracefully for that folder only. Just copy setup.cfg to whatever other projects you might have. No need to write a .pydistutils.cfg on your home directory.

After you are done installing the modules, you may remove setup.cfg.

On OSX(mac), assuming a project folder called /var/myproject

1. cd /var/myproject
2. Create a file called setup.cfg and add [install] prefix=
3. Run pip install <packagename> -t .

Another solution* for Homebrew users is simply to use a virtualenv.

Of course, that may remove the need for the target directory anyway – but even if it doesn’t, I’ve found --target works by default (as in, without creating/modifying a config file) when in a virtual environment.

*I say solution; perhaps it’s just another motivation to meticulously use venvs…

I hit errors with the other recommendations around --install-option="--prefix=lib". The only thing I found that worked is using PYTHONUSERBASE as described here.

export PYTHONUSERBASE=lib
pip install -I flask-restful --user

this is not exactly the same as --target, but it does the trick for me in any case.

As other mentioned, this is known bug with pip & python installed with homebrew.

If you create ~/.pydistutils.cfg file with “empty prefix” instruction it will fix this problem but it will break normal pip operations.

Until this bug is officially addressed, one of the options would be to create your own bash script that would handle this case:

 #!/bin/bash

 name=''
 target=''

 while getopts 'n:t:' flag; do
     case "${flag}" in
         n) name="${OPTARG}" ;;
         t) target="${OPTARG}" ;;
     esac
 done

 if [ -z "$target" ];
 then
     echo "Target parameter must be provided"
     exit 1
 fi

 if [ -z "$name" ];
 then
     echo "Name parameter must be provided"
     exit 1
 fi

 # current workaround for homebrew bug
 file=$HOME'/.pydistutils.cfg'
 touch $file

 /bin/cat <<EOM >$file
 [install]
 prefix=
 EOM
 # end of current workaround for homebrew bug

 pip install -I $name --target $target

 # current workaround for homebrew bug
 rm -rf $file
 # end of current workaround for homebrew bug

This script wraps your command and:

1. accepts name and target parameters
2. checks if those parameters are empty
3. creates ~/.pydistutils.cfg file with “empty prefix” instruction in it
4. executes your pip command with provided parameters
5. removes ~/.pydistutils.cfg file

This script can be changed and adapted to address your needs but you get idea. And it allows you to run your command without braking pip. Hope it helps :)

If you’re using virtualenv*, it might be a good idea to double check which pip you’re using.

If you see something like /usr/local/bin/pip you’ve broken out of your environment. Reactivating your virtualenv will fix this:

VirtualEnv: $ source bin/activate

VirtualFish: $ vf activate [environ]

*: I use virtualfish, but I assume this tip is relevant to both.

I have a similar issue. I use the –system flag to avoid the error as I decribe here on other thread where I explain the specific case of my situation. I post this here expecting that can help anyone facing the same problem.