ndbm(3) [ultrix man page]

ndbm(3) 						     Library Functions Manual							   ndbm(3)

Name
       dbm_open, dbm_close, dbm_fetch, dbm_store, dbm_delete, dbm_firstkey, dbm_nextkey, dbm_error, dbm_clearerr - data base subroutines

Syntax
       #include <ndbm.h>

       typedef struct {
	   char *dptr;
	   int dsize;
       } datum;

       DBM *dbm_open(file, flags, mode)
	   char *file;
	   int flags, mode;

       void dbm_close(db)
	   DBM *db;

       datum dbm_fetch(db, key)
	   DBM *db;
	   datum key;

       int dbm_store(db, key, content, flags)
	   DBM *db;
	   datum key, content;
	   int flags;

       int dbm_delete(db, key)
	   DBM *db;
	   datum key;

       datum dbm_firstkey(db)
	   DBM *db;

       datum dbm_nextkey(db)
	   DBM *db;

       int dbm_error(db)
	   DBM *db;

       int dbm_clearerr(db)
	   DBM *db;

Description
       These  functions  maintain  key/content	pairs  in a data base.	The functions will handle very large (a billion blocks) databases and will
       access a keyed item in one or two file system accesses.	This package replaces the earlier library, which managed only a single database.

       The keys and contents are described by the datum typedef.  A datum specifies a string of dsize bytes pointed to by dptr.  Arbitrary  binary
       data,  as  well	as normal ASCII strings, are allowed.  The data base is stored in two files.  One file is a directory containing a bit map
       and has .dir as its suffix.  The second file contains all data and has .pag as its suffix.

       Before a database can be accessed, it must be opened by dbm_open.  This will open and/or create the files file.dir and  file.pag  depending
       on the flags parameter (see

       Once open, the data stored under a key is accessed by dbm_fetch and data is placed under a key by dbm_store.  The flags field can be either
       DBM_INSERT or DBM_REPLACE.  DBM_INSERT will only insert new entries into the database and will not change an existing entry with  the  same
       key.   DBM_REPLACE will replace an existing entry if it has the same key.  A key (and its associated contents) is deleted by dbm_delete.  A
       linear pass through all keys in a database may be made,	in  an	(apparently)  random  order,  by  use  of  dbm_firstkey  and  dbm_nextkey.
       dbm_firstkey will return the first key in the database.	dbm_nextkey will return the next key in the database.  This code will traverse the
       data base:

	      for (key = dbm_firstkey(db); key.dptr != NULL; key = dbm_nextkey(db))

       dbm_error returns non-zero when an error has occurred reading or writing the database.  dbm_clearerr resets  the  error	condition  on  the
       named database.

Diagnostics
       All  functions that return an int indicate errors with negative values.	A zero return indicates ok.  Routines that return a datum indicate
       errors with a null (0) dptr.  If dbm_store called with a flags value of DBM_INSERT finds an existing entry with the same key it returns 1.

Restrictions
       The `.pag' file will contain holes so that its apparent size is about four times its actual content.  Older systems may	create	real  file
       blocks for these holes when touched.  These files cannot be copied by normal means ( without filling in the holes.

       dptr pointers returned by these subroutines point into static storage that is changed by subsequent calls.

       The  sum of the sizes of a key/content pair must not exceed the internal block size (currently 4096 bytes).  Moreover all key/content pairs
       that hash together must fit on a single block.  dbm_store will return an error in the event that a disk block fills with inseparable data.

       dbm_delete does not physically reclaim file space, although it does make it available for reuse.

       The order of keys presented by dbm_firstkey and dbm_nextkey depends on a hashing function, not on anything interesting.

See Also
																	   ndbm(3)

ndbm(3) 						     Library Functions Manual							   ndbm(3)

Name
       dbm_open, dbm_close, dbm_fetch, dbm_store, dbm_delete, dbm_firstkey, dbm_nextkey, dbm_error, dbm_clearerr - data base subroutines

Syntax
       #include <ndbm.h>

       typedef struct {
	   char *dptr;
	   int dsize;
       } datum;

       DBM *dbm_open(file, flags, mode)
	   char *file;
	   int flags, mode;

       void dbm_close(db)
	   DBM *db;

       datum dbm_fetch(db, key)
	   DBM *db;
	   datum key;

       int dbm_store(db, key, content, flags)
	   DBM *db;
	   datum key, content;
	   int flags;

       int dbm_delete(db, key)
	   DBM *db;
	   datum key;

       datum dbm_firstkey(db)
	   DBM *db;

       datum dbm_nextkey(db)
	   DBM *db;

       int dbm_error(db)
	   DBM *db;

       int dbm_clearerr(db)
	   DBM *db;

Description
       These  functions  maintain  key/content	pairs  in a data base.	The functions will handle very large (a billion blocks) databases and will
       access a keyed item in one or two file system accesses.	This package replaces the earlier library, which managed only a single database.

       The keys and contents are described by the datum typedef.  A datum specifies a string of dsize bytes pointed to by dptr.  Arbitrary  binary
       data,  as  well	as normal ASCII strings, are allowed.  The data base is stored in two files.  One file is a directory containing a bit map
       and has .dir as its suffix.  The second file contains all data and has .pag as its suffix.

       Before a database can be accessed, it must be opened by dbm_open.  This will open and/or create the files file.dir and  file.pag  depending
       on the flags parameter (see

       Once open, the data stored under a key is accessed by dbm_fetch and data is placed under a key by dbm_store.  The flags field can be either
       DBM_INSERT or DBM_REPLACE.  DBM_INSERT will only insert new entries into the database and will not change an existing entry with  the  same
       key.   DBM_REPLACE will replace an existing entry if it has the same key.  A key (and its associated contents) is deleted by dbm_delete.  A
       linear pass through all keys in a database may be made,	in  an	(apparently)  random  order,  by  use  of  dbm_firstkey  and  dbm_nextkey.
       dbm_firstkey will return the first key in the database.	dbm_nextkey will return the next key in the database.  This code will traverse the
       data base:

	      for (key = dbm_firstkey(db); key.dptr != NULL; key = dbm_nextkey(db))

       dbm_error returns non-zero when an error has occurred reading or writing the database.  dbm_clearerr resets  the  error	condition  on  the
       named database.

Diagnostics
       All  functions that return an int indicate errors with negative values.	A zero return indicates ok.  Routines that return a datum indicate
       errors with a null (0) dptr.  If dbm_store called with a flags value of DBM_INSERT finds an existing entry with the same key it returns 1.

Restrictions
       The `.pag' file will contain holes so that its apparent size is about four times its actual content.  Older systems may	create	real  file
       blocks for these holes when touched.  These files cannot be copied by normal means ( without filling in the holes.

       dptr pointers returned by these subroutines point into static storage that is changed by subsequent calls.

       The  sum of the sizes of a key/content pair must not exceed the internal block size (currently 4096 bytes).  Moreover all key/content pairs
       that hash together must fit on a single block.  dbm_store will return an error in the event that a disk block fills with inseparable data.

       dbm_delete does not physically reclaim file space, although it does make it available for reuse.

       The order of keys presented by dbm_firstkey and dbm_nextkey depends on a hashing function, not on anything interesting.

See Also
																	   ndbm(3)