ls_exts

#!/usr/bin/env python2.7

import os
import sys


def exts_in_dir(dir_name, report_backups=False):
  """Returns a set containing all extensions for file names in directory `dir_name`."""
  all_files = os.listdir(dir_name)
  extensions=set([])

  for fname in all_files:
    if os.path.isfile(fname):
      _, ext = os.path.splitext(fname)
      if report_backups or not ext.endswith("~"):
        extensions.add(ext)

  return extensions


if __name__ == '__main__':
  if len(sys.argv) < 2:
    sys.stderr.write("Usage: {} directory\n".format(os.path.basename(sys.argv[0])))
    sys.stderr.write("       Prints a list of all extensions for files in directory.\n")
    sys.exit(1)
  ext_set = exts_in_dir(sys.argv[1], False)
  for ext in ext_set:
    print(ext)