How do I unlock a SQLite database?

Question

sqlite> DELETE FROM mails WHERE (`id` = 71);
SQL error: database is locked

How do I unlock the database so this will work?

Answer 1

As Seun Osewa has said, sometimes a zombie process will sit in the terminal with a lock aquired, even if you don't think it possible. Your script runs, crashes, and you go back to the prompt, but there's a zombie process spawned somewhere by a library call, and that process has the lock.

Closing the terminal you were in (on OSX) might work. Rebooting will work. You could look for "python" processes (for example) that are not doing anything, and kill them.