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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