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

NAME
       mount, umount - mount and unmount file systems

SYNOPSIS
       /usr/etc/mount [	-p ]
       /usr/etc/mount -a [ fnv ] [ -t type ]
       /usr/etc/mount  [  -fnrv	] [ -t type ] [	-o options ] filesystem	direc-
       tory
       /usr/etc/mount [	-vfn ] [ -o options ] filesystem | directory
       /usr/etc/mount -d [ fnvr	] [ -o options ] RFS-resource |	directory

       /usr/etc/umount [ -t type ] [ -h	host ]
       /usr/etc/umount -a [ v ]
       /usr/etc/umount [ -v ] filesystem|directory  ...
       /usr/etc/umount [ -d ] RFS-resource | directory

DESCRIPTION
       mount attaches a	named filesystem to the	file system hierarchy  at  the
       pathname	 location  directory,  which must already exist.  If directory
       has any contents	prior to the mount operation, these remain hidden  un-
       til  the	 filesystem  is	once again unmounted.  If filesystem is	of the
       form host:pathname, it is assumed to be an NFS file system (type	nfs).

       umount unmounts a currently mounted file	system,	which can be specified
       either as a directory or	a filesystem.

       mount and umount	maintain a table of mounted file systems in /etc/mtab,
       described in fstab(5).  If invoked without an argument, mount  displays
       the contents of this table.  If invoked with either a filesystem	or di-
       rectory only, mount searches the	file /etc/fstab	for a matching	entry,
       and mounts the file system indicated in that entry on the indicated di-
       rectory.

       mount also allows the creation of new, virtual file systems using loop-
       back  mounts.   Loopback	 file systems provide access to	existing files
       using alternate pathnames.  Once	a  virtual  file  system  is  created,
       other file systems can be mounted within	it without affecting the orig-
       inal file system.  File systems that are	subsequently mounted onto  the
       original	 file system, however, are visible to the virtual file system,
       unless or until the corresponding mount point in	the virtual file  sys-
       tem is covered by a file	system mounted there.

       Recursive  traversal of loopback	mount points is	not allowed; after the
       loopback	mount of /tmp/newroot, the file	/tmp/newroot/tmp/newroot  does
       not contain yet another file system hierarchy.  Rather, it appears just
       as /tmp/newroot did before the loopback mount was performed (say, as an
       empty directory).

       The standard RC files first perform 4.2 mounts, then nfs	mounts,	during
       booting.	 On Sun386i systems, lo	(loopback) mounts are  performed  just
       after 4.2 mounts.  /etc/fstab files depending on	alternate mount	orders
       at boot time will fail to work as  expected.   Manual  modification  of
       /etc/rc.local will be needed to make such mount orders work.

       See lofs(4S) and	fstab(5) for more information and WARNINGS about loop-
       back mounts.

OPTIONS
   mount
       -p     Print the	list of	mounted	file systems in	a format suitable  for
	      use in /etc/fstab.

       -a     All.   Attempt  to  mount	 all  the  file	 systems  described in
	      /etc/fstab.  If a	type argument is specified with	-t, mount  all
	      file  systems of that type.  Using -a, mount builds a dependency
	      tree of mount points in /etc/fstab.  mount will correctly	 mount
	      these  file systems regardless of	their order in /etc/fstab (ex-
	      cept loopback mounts; see	WARNINGS below).

       -f     Fake an /etc/mtab	entry, but do not actually mount any file sys-
	      tems.

       -n     Mount the	file system without making an entry in /etc/mtab.

       -v     Verbose.	 Display  a  message indicating	each file system being
	      mounted.

       -t type
	      Specify a	file system type.  The accepted	types  are  4.2,  nfs,
	      rfs,  lo,	hsfs, and tmp.	See fstab(5) for a description of 4.2,
	      hsfs, and	nfs; see lofs(4S) for a	description  of	 lo;  and  see
	      tmpfs(4) for a description of tmp.  See for details on rfs.

       -r     Mount  the specified file	system read-only, even if the entry in
	      /etc/fstab specifies that	it is to be mounted read-write.

	      Physically write-protected and magnetic-tape file	 systems  must
	      be mounted read-only. Otherwise errors occur when	the system at-
	      tempts to	update access times, even if no	write operation	is at-
	      tempted.

       -d     Mount  an	 RFS  file  system. This option	provides compatibility
	      with the System V, Release 3 syntax  for	RFS  mounts.  Alterna-
	      tively, the equivalent Sun syntax, -t rfs, may be	used.

       -o options
	      Specify  file  system  options,  a comma-separated list of words
	      from the list below.  Some options are valid for all file	system
	      types, while others apply	to a specific type only.

	      options valid on all file	systems:

		     rw|ro	   Read/write or read-only.
		     suid|nosuid   Setuid execution allowed or disallowed.
		     grpid	   Create  files  with	BSD  semantics for the
				   propagation of the group  ID.   Under  this
				   option, files inherit the GID of the	direc-
				   tory	in which they are created,  regardless
				   of the directory's set-GID bit.
		     noauto	   Do  not mount this file system that is cur-
				   rently mounted read-only.  If the file sys-
				   tem	is not currently mounted, an error re-
				   sults.
		     remount	   If the file system  is  currently  mounted,
				   and	if  the	 entry in /etc/fstab specifies
				   that	it is to be mounted read-write	or  rw
				   was	specified  along with remount, remount
				   the file system making it  read-write.   If
				   the	entry  in /etc/fstab specifies that it
				   is to be mounted read-only and rw  was  not
				   specified,  the  file  system  is  not  re-
				   mounted.  If	the file system	 is  currently
				   mounted  read-write,	 specifying  ro	 along
				   with	remount	results	in an error.   If  the
				   file	 system	 is  not currently mounted, an
				   error results.

		     The default is `rw,suid'.

	      options specific to 4.2 file systems:

		     quota|noquota  Usage limits are enforced, or are not  en-
				    forced.  The default is noquota.

	      options specific to nfs (NFS) file systems:

		     bg|fg	   If  the  first  attempt fails, retry	in the
				   background, or, in the foreground.
		     noquota	   Prevent quota(1) from checking 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.
		     retry=n	   The number of times to retry	the mount  op-
				   eration.
		     rsize=n	   Set the read	buffer size to n bytes.
		     wsize=n	   Set the write buffer	size to	n bytes.
		     timeo=n	   Set	the  NFS timeout to n tenths of	a sec-
				   ond.
		     retrans=n	   The number of NFS retransmissions.
		     port=n	   The server IP port number.
		     soft|hard	   Return an error if the server does not  re-
				   spond,  or continue the retry request until
				   the server responds.
		     intr	   Allow keyboard interrupts on	hard mounts.
		     secure	   Use a more secure protocol for NFS transac-
				   tions.
		     posix	   Request POSIX.1 semantics for the file sys-
				   tem.	 Requires a mount version 2 mountd(8C)
				   on the server.
		     acregmin=n	   Hold	 cached	attributes for at least	n sec-
				   onds	after file modification.
		     acregmax=n	   Hold	cached attributes for no more  than  n
				   seconds after file modification.
		     acdirmin=n	   Hold	 cached	attributes for at least	n sec-
				   onds	after directory	update.
		     acdirmax=n	   Hold	cached attributes for no more  than  n
				   seconds after directory update.
		     actimeo=n	   Set min and max times for regular files and
				   directories to n seconds.
		     nocto	   Suppress fresh attributes  when  opening  a
				   file.
		     noac	   Suppress   attribute	  and	name  (lookup)
				   caching.

		     Regular defaults are:
			    fg,retry=10000,timeo=7,retrans=3,port=NFS_PORT,hard,\
			    acregmin=3,acregmax=60,acdirmin=30,acdirmax=60

		     actimeo has  no  default;	it  sets  acregmin,  acregmax,
		     acdirmin and acdirmax

		     Defaults  for  rsize  and wsize are set internally	by the
		     system kernel.

	      options specific to rfs (RFS) file systems:

		     bg|fg	   If the first	attempt	fails,	retry  in  the
				   background, or, in the foreground.
		     retry=n	   The	number of times	to retry the mount op-
				   eration.

		     Defaults are the same as for NFS.

	      options specific to hsfs (HSFS) file systems:

		     norrip	   Disable processing of Rock Ridge extensions
				   for the file	system.

   umount
       -h host
	      Unmount  all  file  systems listed in /etc/mtab that are remote-
	      mounted from host.

       -t type
	      Unmount all file systems listed in /etc/mtab that	are of a given
	      type.

       -a     Unmount  all  file  systems  currently  mounted  (as  listed  in
	      /etc/mtab).

       -v     Verbose.	Display	a message indicating each  file	 system	 being
	      unmounted.

       -d     Unmount  an RFS file system.  This option	provides compatibility
	      with the System V, Release 3 syntax for unmounting an  RFS  file
	      system.

NFS FILESYSTEMS
   Background vs. Foreground
       Filesystems  mounted with the bg	option indicate	that mount is to retry
       in the background if the	server's mount daemon  (mountd(8C))  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 num-
       ber 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.

   Read-Write vs. Read-Only
       File systems that are mounted rw	(read-write) should use	the  hard  op-
       tion.

   Interrupting	Processes With Pending NFS Requests
       The  intr  option  allows keyboard interrupts to	kill a process that is
       hung while waiting for a	response on a hard-mounted file	system.

   Quotas
       Quota checking on NFS file systems is performed by the server, not  the
       client;	if  the	 file system has the quota option on the server, quota
       checking	is performed for both local requests and NFS requests.	When a
       user  logs  in, login(1)	runs the quota(1) program to check whether the
       user is over their quota	on any of the file systems mounted on the  ma-
       chine.	This check is performed	for NFS	file systems by	an RPC call to
       the rquotad(8C) server on the machine from which	 the  file  system  is
       mounted.	  This can be time-consuming, especially if the	remote machine
       is down.	 If the	noquota	option is specified for	an  NFS	 file  system,
       quota  will not check whether the user is over their quota on that file
       system, which can speed up the process of logging in.   This  does  not
       disable	quota  checking	 for operations	on that	file system; it	merely
       disables	reporting whether the user is over quota on that file system.

   Secure Filesystems
       The secure option must be given if the server requires secure  mounting
       for the file system.

   File	Attributes
       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  extends  flush  time	 by n seconds for both regular
       files and directories.

SYSTEM V COMPATIBILITY
   System V File-Creation Semantics
       Ordinarily, when	a file is created its GID is set to the	effective  GID
       of  the	calling	process.  This behavior	may be overridden on a per-di-
       rectory basis, by setting the set-GID bit of the	parent	directory;  in
       this  case,  the	 GID  is  set  to the GID of the parent	directory (see
       open(2V)	and mkdir(2V)).	  Files	 created  on  file  systems  that  are
       mounted with the	grpid option will obey BSD semantics; that is, the GID
       is unconditionally inherited from that of the parent directory.

EXAMPLES
	      To mount a local disk:
		     mount /dev/xy0g /usr
	      To fake an entry for nd root:
		     mount -ft 4.2 /dev/nd0 /
	      To mount all 4.2 file systems:
		     mount -at 4.2
	      To mount a remote	file system:
		     mount -t nfs serv:/usr/src	/usr/src
	      To mount a remote	file system:
		     mount serv:/usr/src /usr/src
	      To hard mount a remote file system:
		     mount -o hard serv:/usr/src /usr/src
	      To mount an RFS remote file system, retrying in  the  background
	      on failure:
		     mount -d -o bg SRC	/usr/src
	      To mount an RFS remote file system read-only:
		     mount -t rfs -r SRC /usr/src
	      To save current mount state:
		     mount -p >	/etc/fstab
		     Note:  this  is  not  recommended	when running the auto-
		     mounter, see automount(8).
	      To loopback mount	file systems:
		     mount -t lo /export/tmp/localhost /tmp
		     mount -t lo /export/var/localhost /var lo
		     mount -t lo /export/cluster/sun386.sunos4.0.1 /usr/cluster
		     mount -t lo /export/local/sun386 /usr/local

FILES
       /etc/mtab	   table of mounted file systems
       /etc/fstab	   table of file systems mounted at boot

WARNINGS
       mount does not understand the  mount  order  dependencies  involved  in
       loopback	mounting.  Loopback mounts may be dependent on two mounts hav-
       ing been	previously performed, while nfs	and 4.2	mounts	are  dependent
       only  on	 a  single previous mount.  As a rule of thumb,	place loopback
       mounts at the end of the	/etc/fstab file.  See lofs(4S) for a  complete
       description.

SEE ALSO
       mkdir(2V),   mount(2V),	 open(2V),  unmount(2V),  lofs(4S),  fstab(5),
       mtab(5),	automount(8), mountd(8C), nfsd(8)

BUGS
       Mounting	file systems full of garbage crashes the system.

       If the directory	on which a file	system is to be	mounted	is a  symbolic
       link, the file system is	mounted	on the directory to which the symbolic
       link refers, rather than	being mounted on top of	the symbolic link  it-
       self.

				 19 June 1991			      MOUNT(8)

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | NFS FILESYSTEMS | SYSTEM V COMPATIBILITY | EXAMPLES | FILES | WARNINGS | SEE ALSO | BUGS

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