foo.sh

json() {
  python - $@ <<"EOS"
import json, sys
try:
  obj = json.load(open(sys.argv[1]))
  for key in sys.argv[2:]: obj = obj[key if type(obj) == dict else int(key)]
except ValueError as msg: sys.stderr.write('Invalid JSON: %s\n' % msg); exit(1)
except KeyError as msg: sys.stderr.write('Key "%s" does not exist\n' % key); exit(2)
if type(obj) == dict: print '\n'.join(obj.keys())
elif type(obj) == list: print '\n'.join(obj)
else: print obj
EOS
  return $?
}

JSON="json package.json"
for key in $($JSON engines); do
  echo $key: $($JSON engines $key)
done