I have found most python modules in python source directory, under Python/Lib or Python/Modules ,but where is the sys (import sys) module ? I didn't find it .
The Answer
I find it here: ./Python/sysmodule.c
If you're on Linux or Mac OS X, and in doubt, just try find . -name 'sysmodule.c' in the Python directory.
Other Stuff
The way I found it was by searching for the string "platform" throughout the Python directory (using TextMate), as I've used e.g. sys.platform before from the sys module... something similar can be done with grep and xargs.
Another suggestion could be : for i in ./**/*.c ; do grep -H platform $i ; done
This will loop through all *.c files present in anywhere up the file tree you're currently located at, and search the file for "platform". The -H flag will ensure we get a filename path so we can trace the matches back to the files they are found in.
where is the sys module in python source code?