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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 functions

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 treated as O_RDWR 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_close() function normally returns zero.

     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                              July 7, 1999                              BSD