man nbd server Command

Man page for apt-get nbd server Command

Man Page for nbd server in Linux

Ubuntu Man Command : man nbd server

Man Nbd Server  Command

This tutorial shows the man page for man nbd server in linux.

Open terminal with 'su' access and type the command as shown below:
man nbd server

Result of the Command Execution shown below:

NBD SERVER(1)                                                                                                                                          NBD SERVER(1)

nbd server serve a file as a block device to other computers running the GNU/Linux(tm) or GNU/Hurd Operating System

nbd server [ip:]port filename [ size ] [ r ] [ m ] [ c ] [ l host list filename ] [ o section name ] [ C config file ]

nbd server is the server for the Linux Network Block Device (NBD). With NBD, a client can use a file, exported over the network from a server, as a block
device. It can then be used for whatever purpose a normal block device (harddisk, CD ROM, ...) can be used for.

NBD can be useful for diskless clients that need swapspace, but you can also create a filesystem on it and use it as though it were a local filesystem.

nbd server implements some security through a file called "nbd_server.allow" in the current directory (by default; a different file can be chosen with the
' l' option). This file must list the IP addresses of clients that are allowed to connect. If it does not exist, all clients are able to connect. If the
file is empty, no clients can connect.

ip The ip address the server should listen on. If omitted, (aka "any address") is used.

port The port the server should listen to. A valid port is any number between 1 and 65536; if 0 is used, nbd server will listen on stdin (so that nbd
server can be ran from inetd)

The filename of the file that should be exported. This can be any file, including "real" blockdevices (i.e. a file from /dev). If the filename
includes the literal string "%s", then this %s will be substituded with the IP address of the client trying to connect.

size The size of the block device at the client side. This is especially usefull in conjunction with the m option

Can optionally be followed by one of K,k,M or m, in which case the size will be multiplied by 1024 (K or k) or 1048576 (M or m)

r Export the file read only. If a client tries to write to a read only exported file, it will receive an error, but the connection will stay up.

m Work with multiple files. This can be used to export blockdevices that are larger than the maximum allowed filesize on a given filesystem; i.e. when
the filesystem does not allow files larger than 2GB (which is true for Linux 2.2 and below), you can use this option to store the data in multiple
files and export a larger filesystem, if needed.

To use this option, you must create a number of files with names in the format "name.X", where "name" is given as the filename argument to nbd server,
and "X" is a number starting by 0 and going up for each file.

Allowing more flexibility for this option is planned for future versions.

c Copy on write. When this option is provided, write operations are not done to the exported file, but to a separate file. This separate file is removed
when the connection is closed, which means that serving this way will make nbd server slow down (especially on large block devices with lots of
writes), and that after disconnecting and reconnecting the client or the server, all changes are lost.

C Specify configuration file. The default configuration file, if this parameter is not specified, is /etc/nbd server/config.

Note that the configuration file is always parsed and the entries in the file used, even if an extra server is specified on the command line. To dis Äê
able the configuration file entirely, either move it away or use the C option to point nbd server(1) to a non existing or empty configuration file.

Also note that if an empty, incomplete, or invalid configuration file is specified, nbd server will produce a warning about failure to parse the con Äê
fig file. If the command line contains a fully specified configuration, this warning is harmless and may be ignored.

host list filename
This argument should contain a list of IP addresses for hosts that may connect to the server. Wildcards are not allowed. If the file does not exist,
it is ignored (and any host can connect); If the file does exist, but is empty, no host can connect. By default, the name 'nbd_server.allow' is used,
and looked for in the current directory, unless nbd server is compiled as a daemon, in which case it is looked for in the root directory.

section name
If the o argument is given on the command line, then nbd server will output a configuration file section with this as the header that is functionally
equivalent to the other options specified on the command line, and exit. This is useful for migrating pre 2.9 nbd server initscript configuration
files to the new format.

Some examples of nbd server usage:

¬" To export a file /export/nbd/exp bl dev on port 2000:

nbd server 2000 /export/nbd/exp bl dev

¬" To export a the same file read only:

nbd server 2000 /export/nbd/exp bl dev r

¬" To export the same file read write, but make sure changes are lost after restarting the client or the server:

nbd server 2000 /export/nbd/exp bl dev c

nbd client (8), nbd server (5),

The NBD kernel module and the NBD tools were originally written by Pavel Machek (

The Linux kernel module is now maintained by Paul Clements (, while the userland tools are maintained by Wouter Verhelst

On The Hurd there is a regular translator available to perform the client side of the protocol, and the use of nbd client is not required. Please see the
relevant documentation for more information.

This manual page was written by Wouter Verhelst (<>) for the Debian GNU/Linux system (but may be used by others). Permission is granted to
copy, distribute and/or modify this document under the terms of the GNU General Public License, version 2, as published by the Free Software Foundation.

04 August 2009 NBD SERVER(1)-

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