executing a command

[andrea valle]

Hi to all,
I need to run a program from inside python (substantially, algorithmic  
batch processing).
I'm on mac osx 10.3.8 with python 2.3 framework and macpython.

Trying to use exec*, I checked references, Brueck & Tanner, and then   
grab this code from effbot:

 >>> program = "python"
 >>> def run(program, *args):
	os.execvp(program, (program,) +  args)
	print "ok"

 >>> run("python", "/Users/apple/Desktop/prova.py")

Traceback (most recent call last):
   File "<pyshell#50>", line 1, in -toplevel-
     run("python", "/Users/apple/Desktop/prova.py")
   File "<pyshell#49>", line 2, in run
     os.execvp(program, (program,) +  args)
   File  
"/System/Library/Frameworks/Python.framework/Versions/2.3/lib/ 
python2.3/os.py", line 336, in execvp
     _execvpe(file, args)
   File  
"/System/Library/Frameworks/Python.framework/Versions/2.3/lib/ 
python2.3/os.py", line 374, in _execvpe
     func(fullname, *argrest)
OSError: [Errno 45] Operation not supported

This OSError seems to be consistend with all exec family. What does it  
mean and how to use exec?

I also tried with. os.system. It works if I invoke python, but it fails  
(in a way I don't know) when I invoke other programs.

For example:
command = "python /Users/apple/Desktop/test.py"
 >>> os.system(command)
0
(test.py write a string in a file. It works)

But with lilypond or with latex I have no output (and in fact it  
doesn't give 0 as result):

 >>> command = "lilypond /Users/apple/Desktop/test.ly"
 >>> os.system(command)
32512
 >>> command = "latex /Users/apple/Desktop/test.tex"
 >>> os.system(command)
32512

Any help is much appreciated

Thanks a lot

-a-