My code creates a dictionary, which is then stored in a variable. I want to write each dictionary to a JSON file, but I want each dictionary to be on a new line.

My dictionary:

hostDict = {"key1": "val1", "key2": "val2", "key3": {"sub_key1": "sub_val2", "sub_key2": "sub_val2", "sub_key3": "sub_val3"}, "key4": "val4"}

Part of my code:

g = open('data.txt', 'a')
with g as outfile:
  json.dump(hostDict, outfile)

This appends each dictionary to 'data.txt' but it does so inline. I want each dictionary entry to be on new line. Any advice would be appreciated.

Your question is a little unclear. If you're generating hostDict in a loop:

with open('data.txt', 'a') as outfile:
    for hostDict in ....:
        json.dump(hostDict, outfile)
        outfile.write('
')

If you mean you want each variable within hostDict to be on a new line:

with open('data.txt', 'a') as outfile:
    json.dump(hostDict, outfile, indent=2)

When the indent keyword argument is set it automatically adds newlines.