GNOMEバージョンを取得する

#!/usr/bin/env python

import os.path
import subprocess
import re

def _splitLines(string):
    ptn = re.compile('\n')
    return ptn.split(string)

def _ptnextract(string):
    ptn = re.compile('^.+(\d+).(\d+).(\d+).*$')
    (ver, rev1, rev2) = ptn.split(string)[1:4]
    return ver

gnomesessions='/usr/bin/gnome-session'
if os.path.exists(gnomesessions):
    print _ptnextract(subprocess.Popen([gnomesessions,'--version'], stdout=subprocess.PIPE).communicate()[0])

gnomeabout='/usr/bin/gnome-about'
if os.path.exists(gnomeabout):
    print _ptnextract(_splitLines(subprocess.Popen([gnomeabout,'--gnome-version'], stdout=subprocess.PIPE).communicate()[0])[0])