|
HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
|
|
NAME | SYNOPSIS | DESCRIPTION | OPTIONS | CONFIGURATION FILE | DISCUSSION | EXAMPLES | USAGE NOTES | FILES | SEE ALSO | AUTHORS | COLOPHON |
|
|
|
exportfs(8) System Manager's Manual exportfs(8)
exportfs - maintain table of exported NFS file systems
/usr/sbin/exportfs [-avi] [-o options,..] [client:/path ..]
/usr/sbin/exportfs -r [-v]
/usr/sbin/exportfs [-av] -u [client:/path ..]
/usr/sbin/exportfs [-v]
/usr/sbin/exportfs -f
/usr/sbin/exportfs -s
An NFS server maintains a table of local physical file systems
that are accessible to NFS clients. Each file system in this
table is referred to as an exported file system, or export, for
short.
The exportfs command maintains the current table of exports for
the NFS server. The master export table is kept in a file named
/var/lib/nfs/etab. This file is read by rpc.mountd when a client
sends an NFS MOUNT request.
Normally the master export table is initialized with the contents
of /etc/exports and files under /etc/exports.d by invoking
exportfs -a. However, a system administrator can choose to add or
delete exports without modifying /etc/exports or files under
/etc/exports.d by using the exportfs command.
exportfs and its partner program rpc.mountd work in one of two
modes: a legacy mode which applies to 2.4 and earlier versions of
the Linux kernel, and a new mode which applies to 2.6 and later
versions, providing the nfsd virtual filesystem has been mounted
at /proc/fs/nfsd or /proc/fs/nfs. On 2.6 kernels, if this
filesystem is not mounted, the legacy mode is used.
In the new mode, exportfs does not give any information to the
kernel, but provides it only to rpc.mountd through the
/var/lib/nfs/etab file. rpc.mountd then manages kernel requests
for information about exports, as needed.
In the legacy mode, exports which identify a specific host, rather
than a subnet or netgroup, are entered directly into the kernel's
export table, as well as being written to /var/lib/nfs/etab.
Further, exports listed in /var/lib/nfs/rmtab which match a non
host-specific export request will cause an appropriate export
entry for the host given in rmtab to be added to the kernel's
export table.
-d kind or --debug kind
Turn on debugging. Valid kinds are: all, auth, call,
general and parse. Debugging can also be turned on by
setting debug= in the [exportfs] section of /etc/nfs.conf.
-a Export or unexport all directories.
-o options,...
Specify a list of export options in the same manner as in
exports(5).
-i Ignore the /etc/exports file and files under /etc/exports.d
directory. Only default options and options given on the
command line are used.
-r Reexport all directories, synchronizing /var/lib/nfs/etab
with /etc/exports and files under /etc/exports.d. This
option removes entries in /var/lib/nfs/etab which have been
deleted from /etc/exports or files under /etc/exports.d,
and removes any entries from the kernel export table which
are no longer valid.
-u Unexport one or more directories.
-f If /proc/fs/nfsd or /proc/fs/nfs is mounted, flush
everything out of the kernel's export table. Fresh entries
for active clients are added to the kernel's export table
by rpc.mountd when they make their next NFS mount request.
-v Be verbose. When exporting or unexporting, show what's
going on. When displaying the current export list, also
display the list of export options.
-s Display the current export list suitable for /etc/exports.
The [exportfs] section of the /etc/nfs.conf configuration file can
contain a debug value, which can be one or more from the list
general, call, auth, parse, all. When a list is given, the
members should be comma-separated.
exportfs will also recognize the state-directory-path value from
both the [mountd] section and the [exportd] section
Exporting Directories
The first synopsis shows how to invoke exportfs when adding new
entries to the export table. When using exportfs -a, all exports
listed in /etc/exports and files under /etc/exports.d are added to
/var/lib/nfs/etab. The kernel's export table is also updated as
needed.
The host:/path argument specifies a local directory to export,
along with the client or clients who are permitted to access it.
See exports(5) for a description of supported options and access
list formats.
IPv6 presentation addresses contain colons, which are already used
to separate the "host" and "path" command line arguments. When
specifying a client using a raw IPv6 address, enclose the address
in square brackets. For IPv6 network addresses, place the prefix
just after the closing bracket.
To export a directory to the world, simply specify :/path.
The export options for a particular host/directory pair derive
from several sources. The default export options are
sync,ro,root_squash,wdelay. These can be overridden by entries in
/etc/exports or files under /etc/exports.d.
A system administrator may override options from these sources
using the -o command-line option on exportfs. This option takes a
comma-separated list of options in the same fashion as one would
specify them in /etc/exports. In this way exportfs can be used to
modify the export options of an already exported directory.
Unexporting Directories
The third synopsis shows how to unexport a currently exported
directory. When using exportfs -ua, all entries listed in
/var/lib/nfs/etab are removed from the kernel export tables, and
the file is cleared. This effectively shuts down all NFS activity.
To remove an export, specify a host:/path pair. This deletes the
specified entry from /var/lib/nfs/etab and removes the
corresponding kernel entry (if any).
Dumping the Export Table
Invoking exportfs without options shows the current list of
exported file systems. Adding the -v option causes exportfs to
display the export options for each export.
The following adds all directories listed in /etc/exports and
files under /etc/exports.d to /var/lib/nfs/etab and pushes the
resulting export entries into the kernel:
# exportfs -a
To export the /usr/tmp directory to host django, allowing insecure
file locking requests from clients:
# exportfs -o insecure_locks django:/usr/tmp
To unexport the /usr/tmp directory:
# exportfs -u django:/usr/tmp
To unexport all exports listed in /etc/exports and files under
/etc/exports.d:
# exportfs -au
To export the /usr/tmp directory to IPv6 link-local clients:
# exportfs [fe80::]/64:/usr/tmp
Exporting to IP networks or DNS and NIS domains does not enable
clients from these groups to access NFS immediately. Rather,
these sorts of exports are hints to rpc.mountd(8) to grant any
mount requests from these clients. This is usually not a problem,
because any existing mounts are preserved in rmtab across reboots.
When unexporting a network or domain entry, any current exports to
members of this group will be checked against the remaining valid
exports and if they themselves are no longer valid they will be
removed.
/etc/exports
input file listing exports, export options, and access
control lists
/etc/exports.d
directory where extra input files are stored. Note: only
files that end with .exports are used.
/var/lib/nfs/etab
master table of exports
/var/lib/nfs/rmtab
table of clients accessing server's exports
exports(5), nfs.conf(5), rpc.mountd(8), exportd(8), netgroup(5)
Olaf Kirch <[email protected]>
Neil Brown <[email protected]>
This page is part of the nfs-utils (NFS utilities) project.
Information about the project can be found at
⟨http://linux-nfs.org/wiki/index.php/Main_Page⟩. If you have a bug
report for this manual page, see
⟨http://linux-nfs.org/wiki/index.php/Main_Page⟩. This page was
obtained from the project's upstream Git repository
⟨git://git.linux-nfs.org/projects/steved/nfs-utils.git⟩ on
2025-08-11. (At that time, the date of the most recent commit
that was found in the repository was 2025-06-27.) If you discover
any rendering problems in this HTML version of the page, or you
believe there is a better or more up-to-date source for the page,
or you have corrections or improvements to the information in this
COLOPHON (which is not part of the original manual page), send a
mail to [email protected]
30 September 2013 exportfs(8)
Pages that refer to this page: exports(5), nfs.conf(5), nfsd(7), exportd(8), mountd(8), nfsconf(8), nfsd(8), nfsdclnts(8)
|
HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
|