Command line string splitting tool

pysplit.py

#!/usr/bin/env python
"""Splits every line in STDIN using str.split. Prints
each field on STDOUT using the indices given as arguments
to the script.

Usage:
    echo 'foo bar baz' | pysplit 2 1 0
    echo 'foo,bar,baz' | pysplit , 2 1 0
"""
import sys

def is_int(string):
    try:
        int(string)
        return True
    except ValueError:
        return False

chars = None
if is_int(sys.argv[1]):
    indices = map(int, sys.argv[1:])
else: # Use the given chars for splitting
    chars = sys.argv[1]
    indices = map(int, sys.argv[2:])

for line in sys.stdin:
    line = line.strip()
    if chars:
        line_parts = line.split(chars)
    else:
        line_parts = line.split()

    for n, index in enumerate(indices):
        sys.stdout.write(line_parts[index])
        if n == len(indices) - 1:
            sys.stdout.write('\n')
        else:
            sys.stdout.write(' ')