exports(4)

NAME
     exports - list of NFS filesystems being exported

SYNOPSIS
     /etc/exports

DESCRIPTION
     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.

     rw=hostname[:hostname]...
               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.

     root=hostname[:hostname]...
               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.

     access=client[:client]...
               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.
     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.

     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 non-
               volatile 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.

     32bitclients
               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.

EXAMPLES
          /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
          /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
     The nohide and wsync options are specific to IRIX.

FILES
     /etc/exports

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