dbm — Simple “database” interface
Platforms: Unix
Note
The dbm module has been renamed to dbm.ndbm in Python 3.0. The
2to3 tool will automatically adapt imports when converting your
sources to 3.0.
The dbm module provides an interface to the Unix “(n)dbm” library. Dbm
objects behave like mappings (dictionaries), except that keys and values are
always strings. Printing a dbm object doesn’t print the keys and values, and the
items() and values() methods are not supported.
This module can be used with the “classic” ndbm interface, the BSD DB
compatibility interface, or the GNU GDBM compatibility interface. On Unix, the
configure script will attempt to locate the appropriate header file
to simplify building this module.
The module defines the following:
-
exception dbm.error
- Raised on dbm-specific errors, such as I/O errors. KeyError is raised for
general mapping errors like specifying an incorrect key.
-
dbm.library
- Name of the ndbm implementation library used.
-
dbm.open(filename[, flag[, mode]])
Open a dbm database and return a dbm object. The filename argument is the
name of the database file (without the .dir or .pag extensions;
note that the BSD DB implementation of the interface will append the extension
.db and only create one file).
The optional flag argument must be one of these values:
Value |
Meaning |
'r' |
Open existing database for reading only
(default) |
'w' |
Open existing database for reading and
writing |
'c' |
Open database for reading and writing,
creating it if it doesn’t exist |
'n' |
Always create a new, empty database, open
for reading and writing |
The optional mode argument is the Unix mode of the file, used only when the
database has to be created. It defaults to octal 0666 (and will be
modified by the prevailing umask).
See also
- Module anydbm
- Generic interface to dbm-style databases.
- Module gdbm
- Similar interface to the GNU GDBM library.
- Module whichdb
- Utility module used to determine the type of an existing database.