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exports(4)							    exports(4)

NAME    [Toc]    [Back]

     exports - list of NFS filesystems being exported

SYNOPSIS    [Toc]    [Back]


DESCRIPTION    [Toc]    [Back]

     The file /etc/exports describes the filesystems that are being exported
     to	NFS clients.  It is created by the system administrator	using a	text
     editor It is processed by exportfs(1M) at system startup and by the mount
     request daemon, mountd(1M), each time a mount request is received.
     exportfs should be	re-executed after making changes to the	file.

     The file consists of a list of filesystems, the netgroup(4) or machine
     names allowed to remote mount each	filesystem and possibly	a list of
     options.  The filesystem names are	left justified and followed by a list
     of	names separated	by white space.	 The names are looked up in
     /etc/netgroup and then in /etc/hosts.  A hyphen indicates the start of
     the options list.	Multiple options are separated by commas.  The default
     options are rw,anon=nobody.

     ro	       Export the directory read-only.	If not specified, the
	       directory is exported read-write.

	       Export the directory read-mostly.  Read-mostly means exported
	       read-only to most machines, but read-write to those specified.
	       If no hosts are specified, the directory	is exported read-write
	       to all.

     anon=uid  If a request comes from a host for uid 0	(typically ``root'')
	       or from a host using null authentication, use uid as the
	       effective user ID.  uid can be either a name or an integer user
	       ID from /etc/passwd.  The default value for this	option is
	       ``nobody'' (uid -2).  Because uid 0 permits access to files
	       regardless of permission	and ownership, NFS servers change uid
	       0 to the	anonymous uid by default.  Use the root	option to
	       permit accesses from hosts using	uid 0.	Setting	the value of
	       uid to -1 disables accesses from	unknown	users or from root on
	       hosts not included in the root option.

	       Give root access	only to	the root (uid 0) users from a
	       specified hostname.  The	default	is for no hosts	to be granted
	       root access.

	       Give mount access to each client	listed.	 A client can either
	       be a hostname, or a netgroup (see netgroup(4)).	Each client in
	       the list	is first checked for in	the /etc/netgroup database and
	       then in the /etc/hosts database.	 The default value allows any
	       machine to mount	the given directory.

									Page 1

exports(4)							    exports(4)

     nohide    Allows a	client who mounts this entry's parent filesystem to
	       access files in this filesystem.	 This is ``off'' by default,
	       preventing a client who mounts this entry's parent filesystem
	       from accessing files in this filesystem.	 Clients who mount a
	       filesystem containing a hidden filesystem access	the directory
	       on which	the hidden child is mounted, not the child
	       filesystem's root directory.  Be	aware that using this option
	       introduces a violation of RFC 1094, RFC 1813, and the XNFS
	       specification.  Using this option may cause the server not to
	       interoperate properly with non-IRIX clients, particularly Linux

     wsync     Causes all writes to this filesystem to be performed
	       synchronously.  With this option, the server waits until
	       written data is safely stored on	a magnetic disk	or other nonvolatile
	medium before sending a	positive response to the
	       client.	Without	this option, the server	performs delayed
	       writes (it responds positively to the client, then writes the
	       data at its convenience or when a sync(2) is executed).
	       Delaying	writes provides	a great	performance boost, but also
	       introduces the risk of losing data if the server	crashes	after
	       the response but	before the data	is stored.  Use	the wsync
	       option if this risk is unacceptable.

	       Causes the server to mask off the high order 32 bits of
	       directory cookies in NFS	version	3 directory operations.	 This
	       option may be required when clients run 32-bit operating
	       systems that assume the entire cookie is	contained in 32	bits
	       and reject responses containing version 3 cookies with high
	       bits on.	 IRIX 5.3 and Solaris 2.5 are examples of 32-bit
	       operating systems with this behavior, which produces error
	       messages	like "Cannot decode response" on directory operations.
	       XFS filesystems on the server can generate cookies with high
	       bits on.	 Exporting filesystems with the	32bitclients option
	       causes these bits to be masked and prevents error messages.

     A filesystem name that is not followed by a name list is exported to
     everyone.	A ``#''	anywhere in the	file indicates a comment extending to
     the end of	the line on which it appears.  A backslash ``\'' at the	end of
     a line permits splitting long lines into shorter ones.  When splitting
     the options across	multiple lines,	the character immediately preceeding
     the backslash must	be one of ``-'', ``='',	``:'', or ``,''.  Also,	no
     whitespace	may follow the backslash nor proceed the first character of
     the next line.

EXAMPLES    [Toc]    [Back]

	  /usr/local		   # export to the world
	  /usr	    clients	   # export to my clients
	  /usr2	    bonnie clyde   # export to only these machines
	  /usr3	    -anon=guest	   # map client	root & anonymous to guest
	  /	    -ro		   # export the	root filesystem

									Page 2

exports(4)							    exports(4)

	  /usr	    -ro,nohide	   # export all	local filesystems read-only
	  /d/local/src	 \
		    -rw,anon=guest,root=bonnie	  # multi-line example

     Exporting all your	machine's local	filesystems requires enumerating all
     local mount points	and using nohide for filesystem	other than root:

	  /	    -ro
	  /usr	    -ro,nohide
	  /d	    -ro,nohide

NOTE    [Toc]    [Back]

     The nohide	and wsync options are specific to IRIX.

FILES    [Toc]    [Back]


SEE ALSO    [Toc]    [Back]

     exportfs(1M), mountd(1M), showmount(1M), netgroup(4), passwd(4).

WARNINGS    [Toc]    [Back]

     You cannot	export a directory that	is either a parent- or a sub-directory
     of	one that is currently exported and within the same filesystem.	It
     would be illegal, for example, to export both /usr	and /usr/local if both
     directories resided in the	same disk partition.

     While there is no hard-coded maximum length, extremely long export	lists
     (hundreds of hosts	or netgroups for a single exported directory) may
     cause mount requests for that exported directory to time out.

									PPPPaaaaggggeeee 3333
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 Similar pages
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getExportList IRIX get list of nfs exported directories from a remote system
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