python -m

python -m lets you run modules as scripts. If your module is just one .py file it'll be executed (which usually means code under if __name__ == '__main__'). If your module is a directory, Python will look for __main__.py (next to __init__.py) and will run it.

One of Python's mottoes is "batteries included", and this goes for python -m as well. Here are some (all?) of the gems hidden in the standard library. Sadly not all of them have help, but I poked around in the source code to see the usage.

json.tool

This is by far the one I use most, it'll indent nicely an JSON input in the standard output and very helpful in combination with curl.

$ curl -sL http://j.mp/1IuxaLD

[{"x":1,"y":2},{"x":3,"y":4},{"x":5,"y":6}]

$ curl -sL http://j.mp/1IuxaLD | python -m json.tool

[

    {

        "x": 1,

        "y": 2

    },

    {

        "x": 3,

        "y": 4

    },

    {

        "x": 5,

        "y": 6

    }

]

zipfile

zipfile will let you view, extract and create zip files - very much like the zip and unzip. Here's the help:

$ python -m zipfile -h

Usage:

    zipfile.py -l zipfile.zip        # Show listing of a zipfile

    zipfile.py -t zipfile.zip        # Test if a zipfile is valid

    zipfile.py -e zipfile.zip target # Extract zipfile into target dir

    zipfile.py -c zipfile.zip src ... # Create zipfile from sources

gzip

Like zipfile, let's you compress and decompress .gz files, like gzip/gunzip. By default it'll compress a file but with -d will decompress.

python -m gzip wordlist.txt  # Will create wordlist.txt.gz

python -m gzip -d wordlist.txt.gz  # Will extract to wordlist.txt

filecmp

Compare two directories.

$ python -m filecmp /tmp/a /tmp/b

diff /tmp/a /tmp/b

Only in /tmp/a : ['1']

Only in /tmp/b : ['2']

Identical files : ['4']

Differing files : ['3']

Encode/Decode

Several modules lets you encode/decode in various formats:

• base64
• uu
• encodings.rot_13
• binhex
• mimify
• quopri

For example

$ echo 'secertpassword' | python -m encodings.rot_13

frpregcnffjbeq

Servers

There are several servers that you can run, the ones I know are SimpleHTTPServer, CGIHTTPServer and smtpd (mail). If you quickly want to serve some files from a directory on your machine, just run:

python -m SimpleHTTPServer

Clients

Modules that provide simple clients to various protocols are:

• ftplib
• poplib
• nttpserver
• smtplib (on localhost only)
• telnetlib

For example if you want to view Star Wars in text mode, do

$ python -m telnetlib towel.blinkenlights.nl

System Info

You can use platform to get some platform information (very much line uname -a) and locale to get locale information. Use mimetype to get the mime type of a file:

$ python -m mimetypes doc.html

type: text/html encoding: None

Python Utilties

• compileall will compile all Python files to .pyc
• dis will show bytecode for a file
• pdb will start the Python debugger on a given file (see here)
• pydoc will show documentation on a module/class/function
• site will print some site information (sys.path, USER_BASE ...)
• sysconfig will show many system related information (such as exec_prefix)
• tabnanny will tell you of you mix tabs and spaces (like starting python with -t or -tt)
• tokenize will print list of tokens in Python file

I mostly use pdb and pydoc, for example:

$ python -m pydoc os.remove

Help on built-in function remove in os:

os.remove = remove(...)

    remove(path)

    

    Remove a file (same as unlink(path)).

Profiling

There are several profiles and timers you can use from the command line:

• cProfile - Show profile information
• profile (use cProfile :)
• timeit - Time how long things run
• pstats - Print output of profiles
• trace - Show tracing information on run

Example:

$ python -m cProfile match.py

         28537 function calls (27503 primitive calls) in 0.057 seconds

   Ordered by: standard name

   ncalls  tottime  percall  cumtime  percall filename:lineno(function)

        1    0.000    0.000    0.000    0.000 :1()

        1    0.000    0.000    0.000    0.000 :1(ArgInfo)

        1    0.000    0.000    0.000    0.000 :1(ArgSpec)

   ...

$ pyton -m timeit 'import math; math.factorial(100)'

100000 loops, best of 3: 12.9 usec per loop

timeit has good help from the command line.

IDLE

You can start IDLE by running python -m idlelib.idle

ensurepip

Python 2.7.9 and 3.x comes with an easy way to install pip. Run python -m ensurepip and pypi is at your service.


That's about it ... What are you favorite python -m tools? Which ones did I miss?

EDIT: The good folks at comp.lang.python reminded me a few I forgot:

unittest

python -m unittest discover will run unittest in discovery mode. Just drop a new Python file starting with test and it'll be picked up next time you run the tests. You can also specify a specific test to run with python -m unittest test_file.py TestClass.test_method.

calendar

python -m calendar will show calendar of the current year. You can also run python -m calendar YEAR to display a specific year and python -m calendar YEAR MONTH to display a specific month.

Easter Eggs

python -m this will display the Python Zen

python -m antigravity will open XKCD comic web page (which my company is named after).