# 11.7. `whichdb` — Guess which DBM module created a database

Note

The `whichdb` module’s only function has been put into the `dbm` module in Python 3. The 2to3 tool will automatically adapt imports when converting your sources to Python 3.

The single function in this module attempts to guess which of the several simple database modules available—`dbm`, `gdbm`, or `dbhash`—should be used to open a given file.

`whichdb.``whichdb`(filename)

  Returns one of the following values: `None` if the file can’t be opened because it’s unreadable or doesn’t exist; the empty string (`''`) if the file’s format can’t be guessed; or a string containing the required module name, such as `'dbm'` or `'gdbm'`.