d2h

#!/usr/bin/env python
# (c) Copyright 2017 Jonathan Simmonds
# Little script to convert between hex and decimal. This single script performs
# both functions and may be renamed between d2h and h2d.
import sys, os

def usage(script_name, hex_to_decimal):
    src = "hex" if hex_to_decimal else "decimal"
    dst = "decimal" if hex_to_decimal else "hex"
    print "usage: %s [-h] [number]" % (script_name)
    print ""
    print "Tiny program to convert a number in %s to %s." % (src, dst)
    print ""
    print "positional arguments:"
    print "  number         %s number. May be ommitted to read from stdin." % (src)
    print ""
    print "optional arguments:"
    print "  -h, --help     Print this message and exit."
    sys.exit(1)

# Work out what functionality we are trying to provide.
script_name = os.path.basename(sys.argv[0])
hex_to_decimal = script_name[0] in ['H', 'h']
# Parse the command line.
argc = len(sys.argv)
lines = []
if argc == 1 and not sys.stdin.isatty():
    for line in sys.stdin:
        lines.append(line)
elif argc == 2:
    arg = sys.argv[1]
    if arg == "-h" or arg == "-help" or arg == "--help":
        usage(script_name, hex_to_decimal)
    lines.append(arg)
else:
    usage(script_name, hex_to_decimal)

# Actual implemetation...
for line in lines:
    if hex_to_decimal:
        print int(line, 16)
    else:
        print hex(int(line))