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]
       /usr/sbin/exportfs -f

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/etab 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 etab 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.

       exportfs  and  it's  partner  program 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.  If this filesystem is not mounted in 2.6, the legacy mode is used.

       In  the	new  mode, exportfs does not give any information to the kernel but only provides it to mountd through the /var/lib/nfs/etab file.
       mountd will listen to requests from the kernel and will provide information as needed.

       In the legacy mode, any export requests which identify a specific host (rather than a subnet or netgroup etc) are entered directly into the
       kernel's  export table as well as being written to /var/lib/nfs/etab.  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/etab with /etc/exports. It removes entries in /var/lib/nfs/etab 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.

       -f     In 'new' mode, flush everything out of the kernels export table. Any clients that are active will get new entries  added	by  mountd
	      when they make their next 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.

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 etab 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 override 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 etab file.

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

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

       To remove an export to a host, specify a host:/path pair. This deletes the specified entry from etab and removes the  corresponding  kernel
       entry (if any).	To remove one or more exports to several hosts, use exportfs -ua.

   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/etab and pushes the resulting export entries into the kernel:

       # exportfs -a

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

       # exportfs -o async django:/usr/tmp

       To unexport the /usr/tmp directory:

       # exportfs -u django:/usr/tmp

       To unexport all the directories listed in /etc/exports:

       # exportfs -au

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 no longer 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>

								   18 July 2003 						       exportfs(8)