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 mount_nfs(1M)						       mount_nfs(1M)




 NAME
      mount, umount - mount and unmount an NFS file systems

 SYNOPSIS
      /usr/sbin/mount [-l] [-p|-v]

      /usr/sbin/mount -a [-F nfs] [-eQ]

      /usr/sbin/mount [-F nfs] [-eQrV] [-o specific_options]
	   {host:path|directory}

      /usr/sbin/mount [-F nfs] [-eQrV] [-o specific_options]
	   host:path directory


      /usr/sbin/umount -a [-F nfs] [-h host] [-v]

      /usr/sbin/umount [-v] [-V] {host:path|directory}

 DESCRIPTION
      The mount command mounts file systems.  Only a superuser can mount
      file systems.  Other users can use mount to list mounted file systems.

      The mount command attaches host:path to directory.  host is a remote
      system, path is a directory on this remote system and directory is a
      directory on the local file tree.	 directory must already exist, be
      given as an absolute path name and will become the name of the root of
      the newly mounted file system.  If either host:path or directory is
      omitted, mount attempts to determine the missing value from an entry
      in the /etc/fstab file.  mount can be invoked on any removable file
      system, except /.

      If mount is invoked without any arguments, it lists all of the mounted
      file systems from the file system mount table, /etc/mnttab.  The
      umount command unmounts mounted file systems.  Only a superuser can
      unmount file systems.

 OPTIONS
      -r   Mount the specified file system read-only.

      -o specific_options
	   Set file system specific options according to a comma-separated
	   list chosen from words below.

	   rw|ro	  resource is mounted read-write or read-only.	The
			  default is rw.

	   suid|nosuid	  Setuid execution allowed or disallowed.  The
			  default is suid.





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	   remount	  If a file system is mounted read-only, remounts
			  the file system read-write.

	   bg|fg	  If the first attempt fails, retry in the
			  background, or, in the foreground.  The default is
			  fg.

	   quota	  Enables quota(1M) to check whether the user is
			  over quota on this file system; if the file system
			  has quotas enabled on the server, quotas will
			  still be checked for operations on this file
			  system.  The default is quota.

	   noquota	  Prevent quota(1M) from checking whether the user
			  exceeded the quota on this file system; if the
			  file system has quotas enabled on the server,
			  quotas will still be checked	for operations on
			  this file system.

	   retry=n	  The number of times to retry the mount operation.
			  The default is 1.

	   vers=<NFS version number>
			  By default, the version of NFS protocol used
			  between the client and the server is the highest
			  one available on both systems. If the NFS server
			  does not support NFS Version 3, then the NFS mount
			  will use NFS Version 2 .

	   port=n	  Set server UDP port number to n (the default is
			  the port customarily used for NFS servers).

	   proto=<transp> Use the transport protocol <transp> for this
			  mount.  Valid values for <transp> are tcp
			  (connection-oriented) and udp (connectionless).
			  The default behavior is to attempt a tcp
			  connection.  If the tcp connection attempt fails
			  when defaulting to tcp, a udp connection will be
			  attempted.

	   grpid	  By default, the GID associated with a newly
			  created file will obey the System V semantics;
			  that is, the GID is set to the effective GID of
			  the calling process.	This behavior may be
			  overridden on a per-directory basis by setting the
			  set-GID bit of the parent directory; in this case,
			  the GID of a newly created file is set to the GID
			  of the parent directory (see open(2) and
			  mkdir(2)).  Files created on file systems that are
			  mounted with the grpid option will obey BSD
			  semantics independent of whether the set-GID bit



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			  of the parent directory is set; that is, the GID
			  is unconditionally inherited from that of the
			  parent directory.

	   rsize=n	  Set the read buffer size to n bytes.	The default
			  value is set by kernel.

	   wsize=n	  Set the write buffer size to n bytes.	 The default
			  value is set by kernel.

	   timeo=n	  Set the NFS timeout to n tenths of a second.	The
			  default value is set by kernel.

	   retrans=n	  Set the number of NFS retransmissions to n.  The
			  default value is 5.

	   soft|hard	  Return an error if the server does not respond, or
			  continue the retry request until the server
			  responds.  The default value is hard.

	   intr|nointr	  Allow (do not allow) keyboard interrupts to kill a
			  process that is hung while waiting for a response
			  on a hard-mounted file system.  The default is
			  intr.

	   noac		  Suppress attribute caching.

	   nocto	  Suppress fresh attributes when opening a file.

	   devs|nodevs	  Allow (do not allow) access to local devices.	 The
			  default is devs.

	   acdirmax=n	  Hold cached attributes for no more than n seconds
			  after directory update.  The default value is 60.

	   acdirmin=n	  Hold cached attributes for at least n seconds
			  after directory update.  The default value is 30.

	   acregmax=n	  Hold cached attributes for no more than n seconds
			  after file modification.  The default value is 60.

	   acregmin=n	  Hold cached attributes for at least n seconds
			  after file modification.  The default value is 3.

	   actimeo=n	  Set min and max times for regular files and
			  directories to n seconds.  actimeo has no default;
			  it sets acregmin, acregmax, acdirmin, and acdirmax
			  to the value specified.

      -O   Overlay mount.  Allow the file system to be mounted over an
	   existing mount point, making the underlying file system



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	   inaccessible.  If a mount is attempted on a pre-existing mount
	   point without setting this flag, the mount will fail, producing
	   the error device busy.

    Options (umount)
      umount recognizes the following options:

	   -a		  Attempt to unmount all file systems described in
			  /etc/mnttab.	All optional fields in /etc/mnttab
			  must be included and supported.  If -F nfs option
			  is specified, all NFS file systems in /etc/mnttab
			  are unmounted.  File systems are not necessarily
			  unmounted in the order listed in /etc/mnttab.

	   -F nfs	  Specify the NFS file system type (see fstyp(1M)).

	   -h host	  Unmount only those file systems listed in
			  /etc/mnttab that are remote-mounted from host.

	   -v		  Verbose mode.	 Write a message to standard output
			  indicating which file system is being unmounted.

	   -V		  Echo the completed command line, but performs no
			  other action.	 The command line is generated by
			  incorporating the user-specified options and other
			  information derived from /etc/fstab.	This option
			  allows the user to verify the command line.

    NFS File Systems
      Background vs. Foreground
	   File systems mounted with the bg option indicate that mount is to
	   retry in the background if the server's mount daemon (mountd(1M))
	   does not respond.  mount retries the request up to the count
	   specified in the retry=n option.  Once the file system is
	   mounted, each NFS request made in the kernel waits timeo=n tenths
	   of a second for a response.	If no response arrives, the time-out
	   is multiplied by 2 and the request is retransmitted.	 When the
	   number of retransmissions has reached the number specified in the
	   retrans=n option, a file system mounted with the soft option
	   returns an error on the request; one mounted with the hard option
	   prints a warning message and continues to retry the request.

      Hard vs. Soft
	   File systems that are mounted read-write or that contain
	   executable files should always be mounted with the hard option.
	   Applications using soft mounted file systems may incur unexpected
	   I/O errors.

	   To improve NFS read performance, files and file attributes are
	   cached.  File modification times get updated whenever a write
	   occurs.  However, file access times may be temporarily out-of-



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	   date until the cache gets refreshed.	 The attribute cache retains
	   file attributes on the client.  Attributes for a file are
	   assigned a time to be flushed.  If the file is modified before
	   the flush time, then the flush time is extended by the time since
	   the last modification (under the assumption that files that
	   changed recently are likely to change soon).	 There is a minimum
	   and maximum flush time extension for regular files and for
	   directories.	 Setting actimeo=n sets flush time to n seconds for
	   both regular files and directories.

 EXAMPLES
      To mount an NFS file system:

	   mount serv:/usr/src /usr/src

      To mount an NFS file system readonly with no suid privileges:

	   mount -r -o nosuid serv:/usr/src /usr/src

      To mount an NFS file system over Version 3:

	   mount -o vers=3 serv:/usr/src /usr/src

      To unmount all file systems imported from a given host, enter the
      following command as root:

	   umount -h mysystem.home.work.com -a

      The hostname must match what is in /etc/mnttab exactly (as shown by
      the bdf command). For example, if bdf shows:

	   mysystem:/projects,

      the umount command would be

	   umount -h mysystem -a.

 FILES
      /etc/mnttab	  table of mounted file systems.
      /etc/fstab	  list of default parameters for each file system.

 SEE ALSO
      fsclean(1M), mount(1M), quotaon(1M), mount(2), fstab(4), mnttab(4),
      fs_wrapper(5), quota(5).

 STANDARDS COMPLIANCE
      mount: SVID3

      umount: SVID3





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