mount, umount - mount or unmount a file system

     mount [-m] -[apfnrvq] [-t type] [-o options] [device] [directory]
     umount [-u] -[afnvq] [-t type] device|directory

     Mount and umount are used to mount and unmount filesystems, or to add and
     remove swap devices.

     Mount instructs the system to extend the file system hierarchy  with  the
     files  on  device at directory.  The previous contents of the mount point
     are hidden by the device until the connection is broken by umount.

     If device is prepared for use as a swap device (with mkfs(1)), then mount
     and  umount may be used to add and remove this swap device if called with
     the option -t swap.

     Both utilities maintain a table of mounted file systems in  /etc/mtab  to
     record  mounts  and  unmounts.   Mount  will use the table /etc/fstab for
     default filesystems, mountpoints and options, except when called with the
     remount  option,  then it will use /etc/mtab like umount.  The table used
     will be referred to as "the table."  If an entry is listed in the  table,
     then  mount  need  not  be called with two arguments, one will do.  Mount
     lists /etc/mtab if called without arguments.

     Mount and umount are normally restricted to users in the  operator  group
     (group-id  0).   Normal users may be allowed to mount or unmount devices,
     floppies for instance, if the user option is placed in  the  fstab  file.
     On  mount  the device will be checked by fsck -n under the permissions of
     the user.  If the check succeeds then the device will be mounted  nosuid.
     The user option is ignored for a privileged user.


     -m   Do the actions of mount even if called as umount.  (They  are  links
          to each other.)

     -u   Do the actions of umount.

     -a   Work on  all  file  systems  in  the  table.   (Forward  for  mount,
          backwards for umount.)

     -p   Make mount give its output  in  the  same  form  as  /etc/fstab  and

     -f   Fake: Update mtab, but do not mount or unmount anything.

     -n   No update: Do the mount or unmount, but do not touch mtab.

     -r   This flag is for backwards compatibility, it is the same as  -o  ro.
          It  is  also  for backwards compatibility that options may be placed
          anywhere on the argument list, because -r was usually at the end.

     -v   Verbose: Tell what's mounted or unmounted.  This is the default  for

     -q   Quiet: Leave the user in the dark.

     -t type
          Mount only file systems of the given type.  It may be  dev  for  any
          file  system  type  (not swap), 1 for Version 1, 2 for Version 2, 1f
          for V1 flex, 2f for V2 flex, swap for a swap device,  or  lo  for  a
          loopback  mount.   If the type can't be obtained from the table then
          dev is assumed.  The type field in fstab may also be ignore with the
          obvious meaning for the entry.

     -o options
          Options is a comma separated list  (no  spaces)  of  mount  options.
          Some of these are fstab specific.

          rw, ro
               Mount the file system read-write (default) or read-only.

               Fstab: Do not use this entry automatically (i.e. -a).  This  is
               the default for the root file system.

          suid, nosuid
               Mount  the  file  system  with  set-user-id   or   set-group-id
               execution  enabled  (default)  or  disabled.   With  the nosuid
               option a user can be allowed to mount an fsck'd floppy  with  a
               limited risk to security.

          grpid, nogrpid
               Let the group-id of a new file be inherited from the directory,
               or  let  the group-id be inherited only if the set-group-id bit
               of the directory is set (default).  The group-id of a new  file
               is  normally  the  effective group-id of the process making the
               new file.

          nf, nonf
               Use a "next fit" strategy for allocating inodes and blocks,  or
               use a "first fit" strategy (default).

          swap, noswap
               The swap option lets the swap space behind the file  system  be
               added  to the system.  The noswap option (default) does not add
               swap space.  Note the difference with the swap type.  A  device
               that  is used for swap completely is of the type swap, a device
               that has both a file system and swap can have this  swap  added
               or removed by option.

               Allow mounts and unmounts by nonprivileged users.  This implies

               Remount the file system with different options,  i.e.   ro  may
               become  rw (but not vice-versa), and nosuid may become suid (or
               vice-versa).  Swap  behind  a  file  system  may  be  added  or

               Use the options found in the fstab file.  This can be used with
               remount  to  set the options of a mounted device to those found
               in the file system table.  The prime use is  in  /etc/rc  where
               you  can  find  the command mount -o remount,fstab / to remount
               the root file system from the read-only state at boot to how it
               should be according to the fstab.

               Make a file system on the  device  before  mounting  it.   This
               requires  a  type  other  than  dev.   This  option  is  highly
               dangerous and should probably only be used on /dev/ram.


     /etc/fstab     List of file systems to mount at boot time.

     /etc/mtab      List of mounted file systems.

     df(1), mkfs(1), fsck(1), mount(2), fstab(5).


     0    No errors.

     1    Errors of any kind.

     2    Root device did not match the entry in fstab.

     Only allow user mounts if your users can be trusted.   While  it  is  not
     possible  to  gain root access due to the nosuid option, it is easy for a
     user to wreck the system by removing a  mounted  floppy.   (If  they  can
     access  the floppy drive then they can also access the big red switch, so
     it is wise to humour them.)

     Kees J. Bot (