# for the docs ... quoting of the filename when you call mailcap.findmatch()

f=";xterm;#.txt" # Shell Command Demo ... xterm will run if quote() fails

import mailcap
import random
try:
  from shlex import quote
except ImportError:
  from pipes import quote
d=mailcap.getcaps()
PY=''.join(random.choice('PYTHON') for i in range(100))
cmd,MIMEtype=mailcap.findmatch(d, 'text/plain', filename=PY)
while "'"+PY+"'" in cmd:
   cmd=cmd.replace("'"+PY+"'",quote(f))
while PY in cmd:
   cmd=cmd.replace(PY,quote(f))
print(cmd)  
# less ';xterm;#.txt'