I noticed importing an executable Python file saves a *.py[co] file, as expected, but that file also is marked executable. Randomly, I wondered if I could execute this file directly, and it worked!
Steps to duplicate:
$ echo 'print "Worked."' > testcase.py
$ chmod u+x testcase.py
$ python -c 'import testcase'
Worked.
$ ./testcase.pyc
Worked.
How did this work? Why didn't I get an error message? Is my system, Ubuntu 9.04, doing something special, or am I forgetting something on how Linux works in general?
$ python --version
Python 2.6.2
$ hd testcase.pyc
00000000 d1 f2 0d 0a a4 4f 08 4b 63 00 00 00 00 00 00 00 |.....O.Kc.......|
00000010 00 01 00 00 00 40 00 00 00 73 09 00 00 00 64 00 |[email protected].|
00000020 00 47 48 64 01 00 53 28 02 00 00 00 73 07 00 00 |.GHd..S(....s...|
00000030 00 57 6f 72 6b 65 64 2e 4e 28 00 00 00 00 28 00 |.Worked.N(....(.|
00000040 00 00 00 28 00 00 00 00 28 00 00 00 00 73 0b 00 |...(....(....s..|
00000050 00 00 74 65 73 74 63 61 73 65 2e 70 79 74 08 00 |..testcase.pyt..|
00000060 00 00 3c 6d 6f 64 75 6c 65 3e 01 00 00 00 73 00 |..<module>....s.|
00000070 00 00 00 |...|
00000073
(Including hexdump to show there's no shebang line, and reading about .pyc format, there's nothing here that isn't highly specific to Python.)