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A convenient way to run python modules, packages and scripts with a dynamically discovered sys.path. Particularly useful when you want to make use of packages without installing them first, or to circumvent bootstrapping issues with complicated collections of python software.

Project description

You can access the most commonly useful features of pyrun, without installing the project, by running the file directly.

For example, the following:

python  my/python/libs my/python/scripts/

Is all you need in order to run the module with a sys.path automatically discovered from directories under my/python/libs. You can list an arbitrary number of directories and paths to actual python files. The order you list them controls the order in which the path extension entries are built. The resulting path will not contain any duplicates. Each entry in the path extension will be a legitimate import path.


A file is provided - with suitable egg entry point declarations - if you prefer this.

For each argument which identifies a python file pyrun will locate the root package directory and add that to the path. The absolute dotted module name of the first python file you identify in this way is the module that will, by default, be executed as __main__. You can explicitly override this choice by using pyrun’s -m option.


root package is the parent directory of the “top most package” see distutils python terms and distutils distutils terms

The delimiter between the pyrun arguments and options and the options for the target module is the first non option argument encountered after the discovery paths. If that option is a pyrun option (see pyrun --help for the list) then pyrun takes it and passes all remaining arguments to the target module in a suitably massaged sys.argv.

If the target module takes arguments but does not naturally accept an option as its first argument (python install is the classic example) then you can artificially terminate the pyrun options with --.

For example it is possible to run the setup script of the pyrun project in the following ways

  • If you have setup tools installed:

    python bdist_egg
  • If your python distribution has not removed distutls from the python standard library:

    python sdist
  • If you have a copy of the setuptools egg in ../python/eggs:

    python ../python/eggs -m setup bdist_egg
    python ../python/eggs -- bdist_egg

If you have a directory which contains a docutils source tree or installation then adding that to the discovery path will let the script build this documentation.

If none of the non option arguments identify a python module file and you dont explicitly select one using -m then pyrun will simply print the path it has discovered and exit. You can force just print the path using -p or -P

pyrun is reasonably smart in respect of python egg distributions. When multiple egg distributions of the same project are found on the discovery path only the best version found is included in the path extension. Eggs which are not compatible with the current python interpreter are ignored. The measure of best egg for a project uses the same algorithm as used by the module distributed by the setuptools project.


The current version does not filter out incompatible platforms for eggs that contain c extensions - see pyrun.filter_best_eggs if you have time on your hands, its not to much work to add this check.

The issue tracker for this package can be found at:

When opening a ticket please assign it to the pyrun component or, at least, mention pyrun in your ticket summary.

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