exportfs(8) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | CONFIGURATION FILE | DISCUSSION | EXAMPLES | USAGE NOTES | FILES | SEE ALSO | AUTHORS | COLOPHON

exportfs(8)              System Manager's Manual             exportfs(8)

NAME         top

       exportfs - maintain table of exported NFS file systems

SYNOPSIS         top

       /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

DESCRIPTION         top

       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.

OPTIONS         top

       -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.

CONFIGURATION FILE         top

       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

DISCUSSION         top

   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.

EXAMPLES         top

       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

USAGE NOTES         top

       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.

FILES         top

       /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

SEE ALSO         top

       exports(5), nfs.conf(5), rpc.mountd(8), exportd(8), netgroup(5)

AUTHORS         top

       Olaf Kirch <okir@monad.swb.de>
       Neil Brown <neilb@cse.unsw.edu.au>

COLOPHON         top

       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
       ⟨http://git.linux-nfs.org/?p=steved/nfs-utils.git;a=summary⟩ on
       2021-06-20.  (At that time, the date of the most recent commit
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       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
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       information in this COLOPHON (which is not part of the original
       manual page), send a mail to man-pages@man7.org

                            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)