Without arguments, this function does nothing. With one argument it
opens the given file as a gdbm database, if this fails for some
reason, an error will be generated. If a second argument is present,
it specifies how to open the database using one or more of the follow
flags in a string:
r | Open database for reading
|
w | Open database for writing
|
c | Create database if it does not exist
|
t | Overwrite existing database
|
f | Fast mode
|
s | Synchronous mode
|
l | Locking mode
|
|
The fast mode prevents the database from syncronizing each change
in the database immediately. This is dangerous because the database
can be left in an unusable state if Pike is terminated abnormally.
The default mode is "rwc"
.