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 the
       [mountd] 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), 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
       2017-09-15.  If you discover any rendering problems in this HTML ver‐
       sion 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 man‐
       ual 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)mountd(8)nfsd(8)