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Edit multiple files using Python text processing modules

Project description

Implements a python mass editor class to process multiple files using Python code. The modification(s) is (are) shown on stdout as a diff output. One can then modify the target file(s) in place with the -w/–write option.


This tool is usefull as far as it goes but it does rely on the python eval() function and does not check the code being executed. It is a major security risk and one should not use this tool in a production environment.

See Ned Batchelder’s article for a thorough discussion of the dangers linked to eval() and ways to circumvent them. Note that None of the counter-measure suggested in the article are implemented at this time.


You probably will need to know the basics of the Python re module (regular expressions).

usage: [-h] [-v] [-w] [-V] [-e EXPRESSIONS] [-s STARTDIR]
                   [-m MAXDEPTH] [-o output]
                   pattern [pattern ...]

Python mass editor

positional arguments:
  pattern               file patterns to process.

optional arguments:
  -h, --help            show this help message and exit
  -v, --version         show program's version number and exit
  -w, --write           modify target file(s) in place. Shows diff otherwise.
  -V, --verbose         increases log verbosity (can be specified multiple
                        Python expressions to be applied on all files. Use the
                        line variable to reference the current line.
  -s START_DIR, --start START_DIR
                        Starting directory in which to look for the files. If
                        there is one pattern only and it includes a directory,
                        the start dir will be that directory and the max depth
                        level will be set to 1.
  -m MAX_DEPTH, --max-depth-level MAX_DEPTH
                        Maximum depth when walking subdirectories.
  -o output, --output output
                        redirect output to a file

example: -e "re.sub('failIf', 'assertFalse', line)" *.py

If massedit is installed as a package (from pypi for instance), one can interact with it as a command line tool :

python -m massedit -e "re.sub('assertEquals', 'assertEqual', line)"

Or as a library (command line option above to be passed as kewyord arguments):

>>> import massedit
>>> filenames = ['']
>>> massedit.edit_files(filenames, ["re.sub('Jerome', 'J.', line)"])

Lastly, there is a convenient massedit.bat wrapper for Windows included in the distribution.


Download from or :

pip install massedit


  • Add support for 3rd party tool (e.g. autopep8) to process the files.
  • Add support for a file of expressions as an argument to allow multiple modification at once.
  • Find a satisfactory way (ie. easy to use) to handle multiline regex as the current version works on a line by line basis.
  • Add magic variables lineno and filename in addition to line.


  • I have a hard time practicing more than a few dialects of regular expressions.
  • I need something portable to Windows without being bothered by eol.
  • I believe Python is the ideal tool to build something more powerful than simple regex based substitutions.


I have been using runsed and checksed (from Unix Power Tools) for years and did not find a good substitute under Windows until I came across Graham Fawcett python recipe 437932 on ActiveState. It inspired me to write the Python Mass Editor.

The core was fleshed up a little, and here we are. If you find it useful and enhance it please, do not forget to submit patches. Thanks!

If you are more interested in awk-like tool, you probably will find pyp a better alternative. This is certainly a more mature tool.


Licensed under the term of MIT License. See attached file LICENSE.txt.


0.61 (2012-07-06)
Added massedit.edit_files function to ease usage as library instead of as a command line tool (suggested by Maxim Veksler).
0.60 (2012-07-04)
Treats arguments as patterns rather than files to ease processing of multiple files in multiple subdirectories. Added -s (start directory) and -m (max depth) options.
0.52 (2012-06-05)
Upgraded for python 3. Still compatible with python 2.7.
0.51 (2012-05)
Initial release (Beta).

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