input from sdtin or file...

[GrelEns]

hello,

i wonder if there is a more pythonic way to do this : having input of a
script either from a file or from stdin if the file is not provided, see
below.
what do you think of it ? is there a better way ?
i have noticed some strange behaviour with stdin having sometimes to do 2 *
ctrl-z to end the input, or also stange temporizing when using os
redirection (like ./myscript.py <smallfile.txt) and script is delayed a lot,
is it a known issue ? or am i missing something ?

best wishes,

------
 file_in = None
 lines = None
 try:
  file_in = args[0]
 except IndexError:
  lines = sys.stdin
 if file_in and not lines:
  try:
   lines = open(file_in, 'r')
  except IOError:
   sys.stderr.write("%s: %s: missing or invalid file argument\n" %
(globals()['_program'], file_in))
   sys.exit(2)
 for line in lines:
  #do what i need

lines.close()