MOUNT(8)MOUNT(8)NAME
mount, umount - mount and dismount file systems
SYNOPSISmount [ -afrwu ] [ -t nfs | ufs | external_type ]
mount [ -frwu ] special | node
mount [ -frwu ] [ -t nfs | ufs | external_type ] [ -o options ] special
node
umount [ -af ] [ -t nfs | ufs | external_type ]
umount [ -f ] special | node
DESCRIPTION
Mount announces to the system that a removable file system is present
on the block device special or the remote node ``rhost:path''. The
file node must exist already and it must be a directory. It becomes
the name of the newly mounted root. The optional arguments -r and -w
indicate that the file system is to be mounted read-only or read-write,
respectively. If either special or file are not provided, the appro‐
priate information is taken from the fstab file. The -f option causes
everything to be done except for the actual system call; if it's not
obvious, this ``fakes'' mounting the file system. This option is use‐
ful in conjunction with the -v flag to determine what the mount command
is trying to do.
The optional argument -t can be used to indicate the file system type.
The type ufs is the default. If the type is not one of the internally
known types, mount will attempt to execute a program in /sbin/mount_XXX
where XXX is replaced by the type name. The standard mount options
(see below) are parsed and passed to external program via the -F option
as a decimal number. Any additional options specific to the program
can be passed as a comma separated list; these options are distin‐
guished by starting with a - (dash). Those options that take a value
are specified using the syntax -option=value. For example, the mount
command:
mount-t mfs -o nosuid,-N,-s=4000 /dev/dk0b /tmp
causes mount to attempt to execute:
/sbin/mount_mfs -F 8 -N -s 4000 /dev/dk0b /tmp
Options are specified by a -o argument followed by a comma separated
string of options. The following options apply to any file system that
is being mounted:
noexec Do not allow execution of any binaries on the mounted file
system. This options is useful for a server that has file
systems containing binaries for architectures other than
its own.
nosuid Do not allow set-user-identifier or set-group-identifier
bits to take effect.
nodev Do not interpret character or block special devices on the
file system. This options is useful for a server that has
file systems containing special devices for architectures
other than its own.
synchronous All I/O to the file system should be done synchronously.
The -u flag indicates that the status of an already mounted file system
should be changed. Any of the options above may be changed; also a
file system can be changed from read-only to read-write. The set of
options is determined by first extracting the options for the file sys‐
tem from the fstab table, then applying any options specified by the -o
argument, and finally applying the -r or -w option.
The following list can be used to override the defaults for an nfs
mount:
hard I/O system calls will retry until the server responds
(default)
soft I/O system calls will fail and return errno after retrans
request retransmissions
spongy Soft semantics for the stat, lookup, fsstat, readlink and
readdir filesystem operations and hard semantics for the
others. This option is meant to be similar to hard, except
that processes will not be hung forever when they trip over
mount points to dead servers.
bg If the first mount request times out, do retries in back‐
ground
intr I/O system calls can be interrupted.
noconn Do not connect the socket. Used for UDP servers that send
replies from a socket other than the nfs server socket.
tcp Use TCP transport instead of UDP.
rsize=# Set read size to # bytes.
wsize=# Set write size to # bytes.
retry=# Set mount retry count to #.
retrans=# Set retransmission count for nfs rpc's to #.
timeo=# Set initial nfs timeout to # in 0.1 sec intervals.
Umount announces to the system that the removable file system node or
whatever removable file system was previously mounted on device special
should be removed. If the -f option is specified for umount, the file
system is forcibly unmounted. Active special devices continue to work,
but all other files return errors if further accesses are attempted.
The root file system cannot be forcibly unmounted.
If the -a option is present for either mount or umount, all of the file
systems described in fstab are mounted or unmounted. The optional
argument -t can be used to indicate that the actions should only be
taken on filesystems of the specified type. More than one type may be
specified in a comma separated list. The list of filesystem types can
be prefixed with ``no'' to specify the filesystem types on which no
action should be taken. For example, the mount command:
mount-a -t nonfs,mfs
mounts all filesystems except those of type NFS and MFS.
The system maintains a list of currently mounted file systems. If
invoked without an argument, mount prints the list. The optional argu‐
ment -t can be used to indicate that only filesystems of the specified
type should be listed. More than one type may be specified in a comma
separated list. The list of filesystem types can be prefixed with
``no'' to indicate the types of filesystems to be excluded from the
listing.
Physically write-protected and magnetic tape file systems must be
mounted read-only or errors will occur when access times are updated,
whether or not any explicit write is attempted.
FILES
/etc/fstab file system table
SEE ALSOmount(2), unmount(2), fstab(5)BUGS
Mounting garbaged file systems will crash the system.
Mounting a root directory on a non-directory makes some apparently good
path names invalid.
4th Berkeley Distribution June 24, 1990 MOUNT(8)
