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

NAME

       exportfs - maintain list of NFS exported file systems

SYNOPSIS

       /usr/sbin/exportfs [-avi] [-o options,..] [client:/path ..]
       /usr/sbin/exportfs -r [-v]
       /usr/sbin/exportfs [-av] -u [client:/path ..]
       /usr/sbin/exportfs [-v]

DESCRIPTION

       The  exportfs  command  is  used to maintain the current table of exported file systems for NFS. This list is kept in a separate file named
       /var/lib/nfs/xtab which is read by mountd when a remote host requests access to mount a file tree, and parts of the list which  are  active
       are kept in the kernel's export table.

       Normally this xtab file is initialized with the list of all file systems named in /etc/exports by invoking exportfs -a.

       However, administrators can choose to add and delete individual file systems without modifying /etc/exports using exportfs.

       Any export requests which identify a specific host (rather than a subnet or netgroup etc) are entered directly into the kernel's export ta-
       ble as well as being written to /var/lib/nfs/xtab.  Further, any mount points 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 entered into the kernel's export table.

OPTIONS

       -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, so that only default options and options given on the command line are used.

       -r     Reexport	all  directories.  It  synchronizes /var/lib/nfs/xtab with /etc/exports. It removes entries in /var/lib/nfs/xtab which are
	      deleted from /etc/exports, and remove any entries from the kernel export table which are no longer valid.

       -u     Unexport one or more directories.

       -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.

DISCUSSION

   Exporting Directories
       The first synopsis shows how to invoke the command when adding new entries to the export table.	When using exportfs -a, all directories in
       exports(5) are added to xtab and the resulting list is pushed into the kernel.

       The host:/path argument specifies the directory to export along with the host or hosts to export it to. All formats described in exports(5)
       are supported; to export a directory to the world, simply specify :/path.

       The  export options for a particular host/directory pair derive from several sources.  There is a set of default options which can be over-
       ridden by entries in /etc/exports (unless the -i option is given).  In addition, the administrator  may	overide  any  options  from  these
       sources	using  the  -o argument which takes a comma-separated list of options in the same fashion as one would specify them in exports(5).
       Thus, exportfs can also be used to modify the export options of an already exported directory.

       Modifications of the kernel export table used by nfsd(8) take place immediately after parsing the command line and updating the xtab file.

       The default export options are sync,ro,root_squash,no_delay.

   Unexporting Directories
       The third synopsis shows how to unexported a currently exported directory.  When using exportfs -ua, all entries listed in xtab are removed
       from the kernel export tables, and the file is cleared. This effectively shuts down all NFS activity.

       To  remove  individial export entries, one can specify a host:/path pair. This deletes the specified entry from xtab and removes the corre-
       sponding kernel entry (if any).

   Dumping the Export Table
       Invoking exportfs without further options shows the current list of exported file systems.  When giving the -v option, the  list  of  flags
       pertaining to each export are shown in addition.

EXAMPLES

       The following adds all directories listed in /etc/exports to /var/lib/nfs/xtab and pushes the resulting export entries into the kernel:

       # exportfs -a

       To export the /usr/tmp directory to host djando, allowing asynchronous writes, one would do this:

       # exportfs -o async django:/usr/tmp

DEPENDENCIES

       Exporting  to  IP networks, DNS and NIS domains does not enable clients from these groups to access NFS immediately; rather, these sorts of
       exports are hints to mountd(8) to grant any mount requests from these clients.  This is usually not a big  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 nolonger valid they will be removed.

SEE ALSO

       exports(5), mountd(8)

AUTHORS

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

								    7 Sep 1999							       exportfs(8)