pipes like perl

[max(01)*]

hi.

in perl i can do this:

...
if (open (MYPIPE, "*some_system_command* |"))
   {
     ...
     *do_something*
     ...
     while ($answer = <MYPIPE>)
       {
         print $answer;
       }
     ...
     *do_something_more*
     ...
   }
else
   {
     ...
     *do_something_else*
     ...
   }
...

but i do not know how to do it in python, because "if *command*:" gives 
syntax error.

moreover, if i use

...
import os
...
try:
   MYPIPE = os.popen("*some_system_command*, "r")
   ...
   *do_something*
   ...
   for answer in MYPIPE:
     print answer,
   MYPIPE.close()
   ...
   *do_something_more*
   ...
except:
   ...
   *do_something_else*
   ...
...

it doesn't work, since "*do_something*" and *do_something_more* are 
always executed (it seems like

MYPIPE = os.popen("*some_system_command*", "r")

does not raise any exception even if *some_system_command* does not 
exist/work...

any help?

thanks a lot

max