Issue with making python program executable

+1 on ignacio's suggestion.

however, to answer the 1st part of your question more directly, each OS/system uses a different line termination character:

POSIX (any Unix-flavor like Linux, *BSD, Mac OS X, etc.) uses \n (NEWLINE) while DOS/Win uses the combo \r\n (CR/carriage return + NEWLINE) and old Mac OS 8 or 9 uses just CR or \r.

to solve this problem, you can run a utility like ignacio has suggested, or you should be able to do it from your text editor (may not be very apparent however).

to answer the other part of your question, the reason why $ python myProgram works is because Python treats all three different line endings the same... the shebang line at the top is ignored because you told Python to load and run that script, and "#" means the first line is a comment and thus ignored.

when you tell your OS shell to run it, it needs to parse that line and execute whatever interpreter you requested, but if it can't, it pukes on you like it did.

hope this helps!

ps. on a side note, you can find out what line-termination character is being used on your operating system, just check out the os.linesep (data) attribute. for example, on my Mac (OS X), i get this:

>>> import os
>>> os.linesep
'\n'

here's a quick summary of the other related attributes that i plagiarized from my hardcore Python intro course notes:

dos2unix filename.py or inside vim issue the command :set fileformat=unix and save.