python - double quote escaping in os.system on windows

Question

I want to escape '"' and all other wild chars in program name and arguments, so I try to double quote them. and I can do this in cmd.exe

C:ayestgo>"test.py" "a" "b"  "c"
hello
['C:\bay\test\go\test.py', 'a', 'b', 'c']

but what's wrong with the following code using os.sytem?

cmd = '"test.py" "a" "b" "c"'
print cmd
os.system(cmd)

its output:

C:ayestgo>test2.py
"test.py" "a" "b" "c"
'test.py" "a" "b" "c' is not recognized as an internal or external command,
operable program or batch file.

Why is the whole string '"test.py" "a" "b" "c"' recognized as a single command? But the following example isn't:

cmd = 'test.py a b c'
print cmd
os.system(cmd)

C:ayestgo>test2.py
test.py a b c
hello
['C:\bay\test\go\test.py', 'a', 'b', 'c']

Thanks!

Answer 1

Furthing google comes this page

http://ss64.com/nt/syntax-esc.html

To launch a batch script which itself requires "quotes" 
CMD /k ""c:atch filesest.cmd" "Parameter 1 with space" "Parameter2 with space"" 

cmd = '""test.py" "a" "b" "c""' does work!