.TH MDB_DUMP 1 "2017/07/31" "LMDB 0.9.70"
.\" Copyright 2014-2021 Howard Chu, Symas Corp. All Rights Reserved.
.\" Copying restrictions apply.  See COPYRIGHT/LICENSE.
.SH NAME
mdb_dump \- LMDB environment export tool
.SH SYNOPSIS
.B mdb_dump
[\c
.BR \-V ]
[\c
.BI \-f \ file\fR]
[\c
.BR \-l ]
[\c
.BR \-n ]
[\c
.BR \-v ]
[\c
.BR \-p ]
[\c
.BR \-a \ |
.BI \-s \ subdb\fR]
.BR \ envpath
.SH DESCRIPTION
The
.B mdb_dump
utility reads a database and writes its contents to the
standard output using a portable flat-text format
understood by the
.BR mdb_load (1)
utility.
.SH OPTIONS
.TP
.BR \-V
Write the library version number to the standard output, and exit.
.TP
.BR \-f \ file
Write to the specified file instead of to the standard output.
.TP
.BR \-l
List the databases stored in the environment. Just the
names will be listed, no data will be output.
.TP
.BR \-n
Dump an LMDB database which does not use subdirectories.
.TP
.BR \-v
Use the previous environment state instead of the latest state.
This may be useful if the latest state has been corrupted.
.TP
.BR \-p
If characters in either the key or data items are printing characters (as
defined by isprint(3)), output them directly. This option permits users to
use standard text editors and tools to modify the contents of databases.

Note: different systems may have different notions about what characters
are considered printing characters, and databases dumped in this manner may
be less portable to external systems. 
.TP
.BR \-a
Dump all of the subdatabases in the environment.
.TP
.BR \-s \ subdb
Dump a specific subdatabase. If no database is specified, only the main database is dumped.
.SH DIAGNOSTICS
Exit status is zero if no errors occur.
Errors result in a non-zero exit status and
a diagnostic message being written to standard error.

Dumping databases that use user-defined comparison functions will output
records with the ordering imposed by those comparison functions. If
.B mdb_load
is invoked without including the
.B -a
option when reloading those records, the new databases will likely be
damaged beyond repair, permitting neither record storage nor retrieval.

.SH "SEE ALSO"
.BR mdb_load (1)
.SH AUTHOR
Howard Chu of Symas Corporation <http://www.symas.com>