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229 lines
4.1 KiB
Groff
229 lines
4.1 KiB
Groff
.\" Copyright (c) 1999 Tim Singletary
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.\" No copyright is claimed.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd April 16, 2006
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.Dt DBM 3
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.Os
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.Sh NAME
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.Nm dbm_clearerr ,
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.Nm dbm_close ,
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.Nm dbm_delete ,
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.Nm dbm_dirfno ,
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.Nm dbm_error ,
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.Nm dbm_fetch ,
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.Nm dbm_firstkey ,
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.Nm dbm_nextkey ,
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.Nm dbm_open ,
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.Nm dbm_store
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.Nd database access functions
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.Sh SYNOPSIS
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.In fcntl.h
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.In ndbm.h
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.Ft DBM *
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.Fn dbm_open "const char *base" "int flags" "int mode"
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.Ft void
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.Fn dbm_close "DBM *db"
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.Ft int
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.Fn dbm_store "DBM *db" "datum key" "datum data" "int flags"
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.Ft datum
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.Fn dbm_fetch "DBM *db" "datum key"
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.Ft int
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.Fn dbm_delete "DBM *db" "datum key"
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.Ft datum
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.Fn dbm_firstkey "DBM *db"
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.Ft datum
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.Fn dbm_nextkey "DBM *db"
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.Ft int
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.Fn dbm_error "DBM *db"
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.Ft int
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.Fn dbm_clearerr "DBM *db"
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.Ft int
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.Fn dbm_dirfno "DBM *db"
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.Sh DESCRIPTION
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Database access functions.
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These functions are implemented using
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.Xr dbopen 3
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with a
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.Xr hash 3
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database.
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.Pp
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.Vt datum
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is declared in
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.In ndbm.h :
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.Bd -literal
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typedef struct {
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char *dptr;
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int dsize;
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} datum;
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.Ed
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.Pp
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The
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.Fn dbm_open base flags mode
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function
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opens or creates a database.
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The
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.Fa base
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argument
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is the basename of the file containing
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the database; the actual database has a
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.Pa .db
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suffix.
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I.e., if
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.Fa base
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is
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.Qq Li /home/me/mystuff
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then the actual database is in the file
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.Pa /home/me/mystuff.db .
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The
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.Fa flags
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and
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.Fa mode
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arguments
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are passed to
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.Xr open 2 .
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.Pq Dv O_RDWR | O_CREAT
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is a typical value for
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.Fa flags ;
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.Li 0660
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is a typical value for
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.Fa mode .
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.Dv O_WRONLY
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is not allowed in
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.Fa flags .
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The pointer returned by
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.Fn dbm_open
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identifies the database and is the
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.Fa db
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argument to the other functions.
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The
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.Fn dbm_open
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function
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returns
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.Dv NULL
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and sets
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.Va errno
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if there were any errors.
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.Pp
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The
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.Fn dbm_close db
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function
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closes the database.
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.Pp
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The
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.Fn dbm_store db key data flags
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function
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inserts or replaces an entry in the database.
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The
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.Fa flags
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argument
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is either
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.Dv DBM_INSERT
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or
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.Dv DBM_REPLACE .
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If
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.Fa flags
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is
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.Dv DBM_INSERT
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and the database already contains an entry for
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.Fa key ,
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that entry is not replaced.
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Otherwise the entry is replaced or inserted.
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The
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.Fn dbm_store
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function
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normally returns zero but returns 1 if the entry could not be
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inserted (because
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.Fa flags
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is
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.Dv DBM_INSERT ,
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and an entry with
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.Fa key
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already exists) or returns -1 and sets
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.Va errno
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if there were any errors.
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.Pp
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The
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.Fn dbm_fetch db key
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function
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returns
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.Dv NULL
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or the
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.Fa data
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corresponding to
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.Fa key .
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.Pp
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The
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.Fn dbm_delete db key
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function
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deletes the entry for
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.Fa key .
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The
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.Fn dbm_delete
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function
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normally returns zero but returns 1 if there was no entry with
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.Fa key
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in the database or returns -1 and sets
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.Va errno
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if there were any errors.
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.Pp
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The
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.Fn dbm_firstkey db
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function
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returns the first key in the database.
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The
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.Fn dbm_nextkey db
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function
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returns subsequent keys.
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The
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.Fn db_firstkey
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function
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must be called before
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.Fn dbm_nextkey .
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The order in which keys are returned is unspecified and may appear
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random.
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The
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.Fn dbm_nextkey
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function
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returns
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.Dv NULL
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after all keys have been returned.
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.Pp
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The
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.Fn dbm_error db
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function
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returns the
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.Va errno
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value of the most recent error.
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The
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.Fn dbm_clearerr db
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function
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resets this value to 0 and returns 0.
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.Pp
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The
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.Fn dbm_dirfno db
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function
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returns the file descriptor to the database.
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.Sh SEE ALSO
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.Xr open 2 ,
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.Xr dbopen 3 ,
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.Xr hash 3
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.Sh STANDARDS
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These functions (except
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.Fn dbm_dirfno )
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are included in the
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.St -susv2 .
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