filedict.py

#!/usr/bin/env python3

"""Interface to a dict stored as json, useful for shell scripts."""

import argparse
import json

parser = argparse.ArgumentParser(description="set/list/get dict contents")
parser.add_argument("file", metavar="FILE", nargs=1, help='Path to dict file')
parser.add_argument("command", metavar="CMD", nargs=1,
                    help='Available: set, keys, items, get, del')
parser.add_argument("args", metavar="ARGS", nargs="*")

ns = parser.parse_args()

command = ns.command[0]

def dump(obj, fp):
    json.dump(obj, fp, sort_keys=True, indent=4, separators=(',', ': '))
    print("", file=fp)

d = {}
try:
    with open(ns.file[0]) as f:
        d = json.load(f)
except FileNotFoundError:
    if command not in ("set"):
        raise

if command == "set":
    d[ns.args[0]] = ns.args[1]
    with open(ns.file[0], "w") as f:
        dump(d, f)
elif command == "keys":
    for s in sorted(d.keys()):
        print(s)
elif command == "items":
    for k, v in sorted(d.items()):
        print(k, "->", v.replace('\n', '\\n').replace('\t', '\\t'))
elif command == "get":
    print(d[ns.args[0]])
elif command == "del":
    del d[ns.args[0]]
    with open(ns.file[0], "w") as f:
        dump(d, f)
else:
    print(parser.format_help())