A simple python template renderer.

substitute.py

#!/usr/bin/python2.7

import sys 
import string

_usage = """ 
Please redirect stdin to the input file, redirect stdout to the output file.
./subtitute.py ARG1=XXX ARG2=YYY < path_to_input > path_to_output\n
"""

def check_input():
    if sys.stdin.isatty():
        sys.stderr.write(_usage)
        exit(-1)

def parse_command_line():
    args = {}
    for arg in sys.argv:
        kv = arg.split('=')
        if len(kv) == 2:
            args[kv[0]] = kv[1]
    return args

def main():
    check_input()
    args = parse_command_line()
    content = sys.stdin.read()
    content = string.Template(content)
    sys.stdout.write(content.safe_substitute(args))


if __name__ == '__main__':
    main()