Post History

The `pip` command accepts an option `--index-url` to specify the primary index (defaults to PyPI) and zero or more `--extra-index-url` options to specify secondary indices. So for your use case, try

```sh
pip install --index-url https://pypi.bar.com/simple --extra-index-url https://pypi.org/simple foo
```
(where I had to assume that your index uses `https://` and `/simple` for the actual index). If you want to configure this permanently and globally, add to your `pip.conf`

```none
[global]
index-url = https://pypi.bar.com/simple
extra-index-url = https://pypi.org/simple
```

If you want to switch between these two, perhaps instead define a shell function with these options for when you want to use them.

```sh
ipi () {
    local cmd=$1
    shift
    pip "$1" --index-url https://pypi.bar.com/simple \
        --extra-index-url https://pypi.org/simple "$@"
}
```
(This is for Bourne-compatible shells; if you are on Windows or using some more arcane shell, see their docs.)

See also [the `pip install` section](https://pip.pypa.io/en/stable/cli/pip_install/) and the [`pip.conf` section](https://pip.pypa.io/en/stable/topics/configuration/) of the `pip` documentation.