Po is a command-line-oriented package manager for Windows. While it aims to include a useful repository of open-source libraries and development tools, it is currently most useful for managing your own projects.

Po is in early development. Most notably, it does not yet manage dependencies.

• Keeps environment variables like PATH and INCLUDE in sync with installed packages. Does not modify your system-wide environment variables.

• Designed from the ground up to support several versions or build configurations per project, and to let you choose which are active.

• Downloads and installs supported third-party packages.

• Define your own local packages to be managed alongside third-party ones.

• Supports source and binary packages.

• Can detect and manage pre-installed software that wasn't installed via Po.

First, install Python 2.7. Once that is installed, open a command window and run this command:

C:\Python27\python -c "exec __import__('urllib2').urlopen('http://raw.github.com/robin-allen/po/master/Scripts/installer.py').read()"

If you didn't install Python to the default location you'll need to change the C:\Python27\python part.

The installer will ask you for two paths. I recommend you just press Enter to use the default for both. The paths are:

• Packages path: This is where Po will install itself, and any packages you install via Po.

• Site path: This is where Po will look for your own custom packages.

Once the installer has finished running, it will give you the path of your Po initialization file. You need to run this file in any command window you intend to use Po in, so you might want to change your command prompt settings to have it always run when you open a new window.

Po keeps track of its packages in its own private environment. To use your packages, you need to enter this environment by typing:

po enter

Your command prompt will change to show you're in the environment. To leave the environment, use the standard Windows command

exit

You can get a full list of commands by doing po help and help on any command with po help <command>.

Po defines a list of so-called "Standard Packages" which it knows how to download and install for you. You can install one of these packages with the command

po install <package-name>

There is currently no way to view or search the list of standard packages, and the list is very short and fairly buggy.

To see what standard packages are available, look in the Recipes subfolder inside Po's "Package Manager" folder.

Po defines a list of "System Packages" corresponding to software which it can detect on your system. Po cannot install this software itself, but it can add the relevant paths to your environment for you.

System packages are useful for managing multiple versions of tools like Python and Microsoft Visual Studio; you can select which version you want to be loaded into the command-line environment with po select and Po will do the rest.

To see what system packages are available, look in the Recipes subfolder inside Po's "Package Manager" folder.

Site packages are defined by you and placed in your Site folder. You write a package.py file and place it inside your package's folder to tell Po how to set up the enviroment for that package. Site packages can be selected and deselected like other packages, and will contribute to the enviroment, but they cannot be automatically installed or uninstalled.

Po does not try to detect when you make changes to a site package; when you do, you need to reload the environment with

po load

To see a list of all installed packages, run

po inv

Each package is shown with its package ID and its human-readable name. Packages which are selected are shown in a brighter font, and deselected packages are shown in a darker font. Only selected packages contribute to the environment.

You can select or deselect a package by giving its ID to the po select and po deselect commands. When several packages have the same ID, as in the case of multiple installed versions, you can specify which package you mean by using package attributes, for example:

po select msvs version=11.0

This would select Visual Studio 11.0 and deselect other versions, so that if you ran a VS tool like cl.exe, you'd get the VS 11.0 version.