dbm(3) BSD Library Functions Manual dbm(3)
NAME
dbm_clearerr, dbm_close, dbm_delete, dbm_dirfno, dbm_error, dbm_fetch,
dbm_firstkey, dbm_nextkey, dbm_open, dbm_store -- database access func-
tions
SYNOPSIS
#include <ndbm.h>
int
dbm_clearerr(DBM *db);
void
dbm_close(DBM *db);
int
dbm_delete(DBM *db, datum key);
int
dbm_dirfno(DBM *db);
int
dbm_error(DBM *db);
datum
dbm_fetch(DBM *db, datum key);
datum
dbm_firstkey(DBM *db);
datum
dbm_nextkey(DBM *db);
DBM *
dbm_open(const char *file, int open_flags, mode_t file_mode);
int
dbm_store(DBM *db, datum key, datum content, int store_mode);
DESCRIPTION
Database access functions. These functions are implemented using
dbopen(3) with a hash(3) database.
datum is declared in <ndbm.h>:
typedef struct {
char *dptr;
int dsize;
} datum;
The dbm_open(file, open_flags, file_mode) function opens or creates a
database file. The file argument is the basename of the file containing
the database; the actual database has a .db suffix. I.e., if file is
"/home/me/mystuff" then the actual database is in the file
/home/me/mystuff.db. The open_flags and file_mode arguments are passed
to open(2). (O_RDWR | O_CREAT) is a typical value for open_flags; 0660
is a typical value for file_mode. O_WRONLY is not allowed in open_flags.
The pointer returned by dbm_open() identifies the database and is the db
argument to the other functions. The dbm_open() function returns NULL
and sets errno if there were any errors.
The dbm_close(db) function closes the database.
The dbm_store(db, key, content, store_mode) function inserts or replaces
an entry in the database. The store_mode argument is either DBM_INSERT
or DBM_REPLACE. If store_mode is DBM_INSERT and the database already
contains an entry for key, that entry is not replaced. Otherwise the
entry is replaced or inserted. The dbm_store() function normally returns
zero but returns 1 if the entry could not be inserted (because store_mode
is DBM_INSERT, and an entry with key already exists) or returns -1 and
sets errno if there were any errors.
The dbm_fetch(db, key) function returns NULL or the content corresponding
to key.
The dbm_delete(db, key) function deletes the entry for key. The
dbm_delete() function normally returns zero but returns 1 if there was no
entry with key in the database or returns -1 and sets errno if there were
any errors.
The dbm_firstkey(db) function returns the first key in the database. The
dbm_nextkey(db) function returns subsequent keys. The db_firstkey()
function must be called before dbm_nextkey(). The order in which keys
are returned is unspecified and may appear random. The dbm_nextkey()
function returns NULL after all keys have been returned.
The dbm_error(db) function returns the errno value of the most recent
error. The dbm_clearerr(db) function resets this value to 0 and returns
0.
The dbm_dirfno(db) function returns the file descriptor to the database.
LEGACY SYNOPSIS
#include <fcntl.h>
#include <ndbm.h>
The include file <ndbm.h> is necessary for all functions.
DBM *
dbm_open(const char *file, int open_flags, int file_mode);
file_mode has type int.
SEE ALSO
open(2), dbopen(3), hash(3), compat(5)
STANDARDS
These functions (except dbm_dirfno()) are included in the Version 2 of
the Single UNIX Specification (``SUSv2'').
BSD April 16, 2006 BSD
Mac OS X 10.8 - Generated Mon Aug 27 15:59:47 CDT 2012