Convert SQLite3 table to JSON (using Python3)

sqlite3_to_json.py

#!/usr/bin/env python3

# I assume that the sqlite3 db file given contains one table,
# and that table has the same name as the file (w/o the extension),
# and that you only want that table.
# This is my use-case anyway; feel free to change it to suit your situation.
# License: CC0 (Public Domain)

import sqlite3
import json
import sys
import os

def die(msg):
    print(msg, file=sys.stderr)
    sys.exit(1)

if len(sys.argv) != 3: die(f'USAGE: {sys.argv[0]} input-file output-file')  # if not 2 args; yes, 2 not 3

_, infile, outfile = sys.argv

if not os.path.isfile(infile): die(f"'{infile}' doesn't exist or is not a file")
if os.path.exists(outfile):    die(f"'{outfile}' exists; please remove it and try again")

tblname = os.path.basename(infile).split('.')[0]

assert tblname.find('"') == -1

c = sqlite3.connect(infile).cursor()

cols = [ row[1] for row in c.execute(f'pragma table_info("{tblname}")') ]

content = [ dict(zip(cols, row)) for row in c.execute(f'select * from "{tblname}"') ]

with open(outfile, 'w') as f:
    json.dump(content, f, ensure_ascii=False, indent=4)