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rerun 1.0.20

Command-line executable Python script to re-run the given command every timefiles are modified in the current directory or its subdirectories.

Latest Version: 1.0.28


rerun [--help|-h] [--verbose|-v] [--ignore|-i=<file>] [--version] <command>


<command>           Command to execute as a single arg, i.e. put it inside
                    double quotes, or else spaces and other special
                    characters should be escaped.
--help|-h           Show this help message and exit.
--ignore|-i=<file>  File or directory to ignore. Any directories of the
                    given name (and their subdirs) are excluded from the
                    search for changed files. Any modification to files of
                    the given name are ignored. The given value is
                    compared to basenames, so for example, "--ignore=def"
                    will skip the contents of directory "./abc/def/" and
                    will ignore file "./ghi/def". Can be specified multiple
--verbose|-v        Display the names of changed files before the command
--version           Show version number and exit.


rerun --verbose --ignore=myoutputdir "python -m unittest mymodule"

This will run your tests whenever you save your source code in the current dir or its subdirectories, but it won’t rerun the tests a second time when .pyo files get updated as a result of executing the tests, nor when our program writes to myoutputdir.

This is handy for seeing the new test results in another console window after you hit ‘save’ in your editor, without having to change window focus.


Rerun detects changes to files by polling file modification times once per second. It looks in the current directory and all its subdirectories. On detecting any changes, it clears the terminal and reruns the given command.

It always ignores directories called .svn, .git, .hg, .bzr, build and dist. Additions to this list can be given using –ignore.

It always ignores files ending with .pyc or .pyo. This isn’t currently user-overrideable.

While polling sounds sub-optimal, I’ve yet to encounter a project large enough that rerun’s resource usage was even noticeable. (Plus, see discussion of ‘watchdog’ below.)


Tested on MacOSX, Ubuntu, WindowsXP, Windows 7.

Tested on Python 2.6, 2.7 and 3.4.

Python 2.6 requires argparse to be installed - see requirements_2.6.txt.

No other dependencies.


To run tests requires mock, tox. On Python 2.6 also requires unittest2. See requirements_dev.txt and requirements_dev_2.6.txt.

See Makefile for a cheatsheet of commonly used commands I use while hacking on this.


pip install rerun

Known Problems

See issues at


PyPI package ‘watchdog’ is a cross-platform library for handling file-system events, which includes script ‘watchmedo’, which looks like a more serious and heavy-duty version of ‘Rerun’.

However, watchmedo doesn’t seem to work for my primary use case, which is re-running tests when files are saved by Vim. This is due to the way Vim writes to temporary files and then moves the temp file to overwrite data atomically. Vim thus guarantees that the user never loses data, but also fails to generate the correct FS events that watchmedo is looking for.


The idea came from the Bash command ‘watch’, and inspiration for this implementation came from an old blog post by Jeff Winkler, whos website seems to have now died.

Thanks to Bitbucket user sgourley for reporting, chasing up and even offering to fix issue #1, an egregious bug in ignoring directories, before I finally spotted the error. Thanks for the prods!


(First release since migration to github) Fix to run under Python 3 again, specifically tested on 3.4.
Now expects commands to be a single arg (i.e. spaces etc should be escaped, or the whole command quoted) thus allowing rerun to work on composite commands, such as pipelines.
Now runs on Python 2.6, and is tested on Python 3.3.


Documentation & download:
Souce code and issues:
Contact the author:
 Jonathan Hartley, email: tartley at domain, Twitter: @tartley.
File Type Py Version Uploaded on Size
rerun-1.0.20.tar.gz (md5) Source 2014-07-27 7KB (md5) Source 2014-07-27 13KB