r"""Command-line tool to validate and pretty-print JSON

Usage::

$ echo '{"json":"obj"}' | python -mjson.tool

{

"json": "obj"

}

$ echo '{ 1.2:3.4}' | python -mjson.tool

Expecting property name: line 1 column 2 (char 2)

"""

import sys

import json

def main():

if len(sys.argv) == 1:

infile = sys.stdin

outfile = sys.stdout

elif len(sys.argv) == 2:

infile = open(sys.argv[1], 'rb')

outfile = sys.stdout

elif len(sys.argv) == 3:

infile = open(sys.argv[1], 'rb')

outfile = open(sys.argv[2], 'wb')

else:

raise SystemExit("{0} [infile [outfile]]".format(sys.argv[0]))

try:

obj = json.load(infile)

except ValueError as e:

raise SystemExit(e)

json.dump(obj, outfile, sort_keys=True, indent=4)

outfile.write('\n')

if __name__ == '__main__':

main()