MOUNT(8) UNIX Programmer's Manual MOUNT(8)
NAME
mount, umount - mount and dismount filesystems
SYNOPSIS
/usr/etc/mount [ -p ]
/usr/etc/mount -a [ vd [ f | n ]] [ -t type ]
/usr/etc/mount [ -rvd [ f | n ]] [ -t type ] [ -o options ]
fsname dir
/usr/etc/mount [ -vd [ f | n ]] [ -o options ] fsname | dir
/usr/etc/umount [ -t type ] [ -h host ]
/usr/etc/umount -a[v]
/usr/etc/umount [ -v ] fsname | dir
DESCRIPTION
The mount command attaches a filesystem fsname to the file
tree at the directory dir. The directory dir may or may not
already exist. If dir already exists, its contents are hid-
den until the filesystem is unmounted, and dir becomes the
name of the newly mounted root. If fsname is of the form
host:path the filesystem type is assumed to be nfs.
The umount command detaches the filesystem fsname previously
mounted on directory dir. Either the filesystem name or the
mounted-on directory may be used.
The mount and umount commands maintain a table of mounted
filesystems in /etc/mtab, described in mtab(5). The mount
command mounts entries onto the filesystem from data it
finds in one of two places. If NetInfo is running, it comes
from netinfo(5). Otherwise, the entries are stored in
/etc/fstab(5). Note that boot time mounts of type "4.3"
filesystems always occur before NetInfo is running, and so
must be stored in /etc/fstab to be seen by the system. If
invoked without an argument, mount displays the table from
/etc/mtab. If invoked with only one of fsname or dir mount
searches the filesystem table for an entry whose dir or
fsname field matches the given argument. For example, if
this line is in /etc/fstab:
/dev/sd1a /usr 4.3 rw 1 1
then the commands mount /usr and mount /dev/sd1a are short
for mount /dev/sd1a /usr
MOUNT OPTIONS
-p Print the list of mounted filesystems in a format suit-
able for use in /etc/fstab.
-a Attempt to mount all the filesystems described in the
filesystem table. (In this case, fsname and dir are
taken from the filesystem table.) If a type is
specified all of the filesystems in the filesystem
table with that type are mounted. Filesystems are not
necessarily mounted in the order listed in the table.
-f Fake a new /etc/mtab entry, but do not actually mount
any filesystems.
-n Mount the filesystems without updating /etc/mtab.
(This can be useful for recovering from an overly full
disk.)
-v Verbose - mount displays a message indicating the
filesystem being mounted.
-d Don't check if NFS mount appears to be mounting a
directory on top of itself. Otherwise, mount ignores
such requests. Since the NFS daemon on a machine might
not have the same filesystem root as the mount process,
this option may be necessary in a chroot'ed environ-
ment.
-t The next argument is the filesystem type. The accepted
types are 4.3, nfs, dos, macintosh, nucfs (NetWare UNIX
Client file system), and cfs (CD-ROM file system). See
fstab(5) for a description of these filesystem types.
-r Mount the specified filesystem read-only. This is
short for:
mount -o ro fsname dir
Physically write-protected and magnetic tape filesys-
tems must be mounted read-only, or errors occur when
access times are updated whether or not any explicit
write is attempted.
-o Specify options, a list of comma-separated words from
the list below. Some options are valid for all
filesystem types, while others apply to a specific type
only.
The following is a list of options valid on all file
systems (the default is rw,suid if the filesystem is
mounted by root and rw,nosuid if the filesystem is not
mounted by root):
rw read/write.
ro read-only.
suid set-uid execution allowed (cannot be specified;
default if root mounts the filesystem).
nosuid set-uid execution not allowed.
noauto do not mount this file system automatically
(mount -a).
remountchange the mount options on this file system
without unmounting it first.
options specific to nfs (NFS) file systems. The
defaults are:
fg,mnttimeo=20,retry=1,timeo=7,retrans=3,port=NFS_PORT,hard
The defaults for rsize and wsize set by the kernel.
bg if the first mount attempt fails, retry in the
background.
fg retry in foreground.
mnttimeo=n
set mount timeout to n seconds.
retry=nset number times to retry mount to n.
rsize=nset read buffer size to n bytes.
wsize=nset write buffer size to n bytes.
timeo=nset NFS timeout to n tenths of a second.
retrans=n
set number of NFS retransmissions to n.
port=n set server IP port number to n.
soft return error if server doesn't respond. Do not
use this option with the rw option.
hard retry request until server responds.
intr allow keyboard interrupts on hard mounts.
net Tell the NFS automounter to recognize this as a
"network" mount. The mount command will ignore
these entries and allow the autonfsmount(8) to
take care of them. This option allows one to
create a uniform view of the network from all
machines. Typically, the mount point specified
is "/Net". A mount of the form "mount -o net
MACHINE:PATH /Net" translates to "mount
MACHINE:PATH /Net/MACHINE/PATH". If the mount
is performed on the machine serving the file
system, then no actual mount occurs. Instead, a
symbolic link is created from "/Net/MACHINE" to
"/".
acregmin=n
set minimum time interval (in seconds) for file
entry caching
acregmax=n
set maximum time interval (in seconds) for file
entry caching
acdirmin=n
set minimum time interval for directory entry
caching
acdirmax=n
set maximum time interval for directory entry
caching
noac set no file attribute caching
The bg option causes mount to run in the background if
the server's mountd(8) does not respond. mount attempts
each request retry=n times before giving up. Once the
filesystem 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 retrans=n
retransmissions have been sent with no reply a soft
mounted filesystem returns an error on the request and
a hard mounted filesystem prints a message and retries
the request. Filesystems that are mounted rw (read-
write) should use the hard option. The intr option
allows keyboard interrupts to kill a process that is
hung waiting for a response on a hard mounted filesys-
tem. The number of bytes in a read or write request
can be set with the rsize and wsize options.
The attribute caching options can be used to defeat or
modify client-side caching of attributes relating to objects
accessed via NFS from a server. Changing these options can
have a severe impact on the client-side performance of an
NFS filesystem. A typical scenario where changing the
parameters is beneficial is a multi-workstation development
environment, where multiple clients are performing
read/write file access to a common source file set.
UMOUNT OPTIONS
-h host
Unmount all filesystems listed in /etc/mtab that are
remote-mounted from host.
-a Attempt to unmount all the filesystems currently
mounted (listed in /etc/mtab). In this case, fsname is
taken from /etc/mtab.
-v Verbose - umount displays a message indicating the
filesystem being unmounted.
EXAMPLES
mount /dev/sd1a /usr mount a local disk
mount -ft 4.3 /dev/nd0 / fake an entry for nd root
mount -at 4.3 mount all 4.3 filesystems
mount -t nfs serv:/usr/src /usr/src mount remote filesystem
mount serv:/usr/src /usr/src same as above
mount -o hard serv:/usr/src /usr/src same as above but hard mount
mount -p > /etc/fstab save current mount state
FILES
/etc/mtab table of mounted filesystems
/etc/fstab table of filesystems mounted at boot
SEE ALSO
mount(2), unmount(2), fstab(5), mountd(8C), nfsd(8C),
netinfo(5)
BUGS
Mounting filesystems full of garbage crashes the system.
If the directory on which a filesystem is to be mounted is a
symbolic link, the filesystem is mounted on the directory to
which the symbolic link refers, rather than being mounted on
top of the symbolic link itself.