7.9 whichdb -- Guess which DBM-style module created a given database.

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 (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".