[Pythonmac-SIG] interaction with OS X commands

[eichin at metacarta.com]

Mmm, looks like subprocess.call() does what os.system should have done
all along, namely what perl does - if you give it an array, it doesn't
do any unsafe string or shell manipulation, it just slots the
arguments into the relevant underlying syscall.  (On the other hand,
spawnv already did that...)

None of the PEP 324 examples deal with actual pipelines, though, so I
can't tell yet if it'll help with my pipeline class (which does
explicit pipe/fork/exec/wait and returns a list of the exit statuses
of the entire pipe - and works with lists, not strings, so it's again
argument-safe.)

I actually use commands.getoutput on ifconfig in some code because
it's a lot more *portable* than doing the GIFCONF ioctls, and if I'm
not allowing any user specified arguments the call is safe enough (I
can tell if it failed simply because the output is verbose enough that
if the parser fails, Something Went Wrong and I can just report that.)
For shell-script-equivalent stuff, it is actually *far* more readable
than any of the Popen.communicate examples in the PEP, and that's
worth a great deal in some contexts.  If anything, I'd like to see the
stuff in commands implemented using subprocess, and then extended to
handle list-arguments; ifconfoutput = commands.getoutput(["ifconfig", "en0"])
would be readable *and* safe, if it were implemented :-)