Net2/usr/src/sbin/mount/mount.8

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.\"     @(#)mount.8	6.16 (Berkeley) 5/4/91
.\"
.Dd May 4, 1991
.Dt MOUNT 8
.Os BSD 4
.Sh NAME
.Nm mount ,
.Nm umount
.Nd mount and dismount file systems
.Sh SYNOPSIS
.Nm mount
.Op Fl afrwu
.Op Fl t Ar nfs | ufs | external_type
.Nm mount
.Op Fl frwu
.Ar special| node
.Nm mount
.Op Fl frwu
.Op Fl t Ar nfs | ufs | external_type
.Op | Ar external_type
.Op Fl o Ar options
.Ar special node
.Nm umount
.Op Fl af
.Op Fl t Ar nfs | ufs | external_type
.Nm umount
.Op Fl f
.Ar special | node
.Sh DESCRIPTION
The
.Nm mount
command
calls the
.Xr mount 2
system call to prepare and graft a
.Ar special
device or the remote node
(rhost:path)
on to the file system tree at the point
.Ar node.
If either
.Ar special
or
.Ar node
are not provided, the appropriate
information is taken from the
.Xr fstab 5
file.
.Pp
The system maintains a list of currently mounted file systems.
If no arguments are given to
.Nm mount,
this list is printed.
.Pp
Options available for the
.Nm mount
command:
.Bl -tag -width indent
.It Fl F
The standard mount options are parsed and
passed to external program via the
.Fl F
option
as a decimal number.
(See example below.)
.It Fl f
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 useful in conjunction with the
.Fl v
flag to
determine what the
.Nm mount
command is trying to do.
.It Fl o
Options are specified with a
.Fl o
flag
followed by a comma separated string of options.
The following options apply to any file system that is being mounted:
.Bl -tag -width indent
.It 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.
.It nosuid
Do not allow set-user-identifier or set-group-identifier bits to take effect.
.It 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.
.It synchronous
All I/O to the file system should be done synchronously.
.El
.It Fl r
The file system object is to be mounted read-only.
.It Fl t Ar "nfs \\*(Ba ufs \\*(Ba external type"
The argument following the
.Fl t
is used to indicate the file system type.
The type
.Ar ufs
is the default.
For example, the
.Nm mount
command:
.Bd -literal -offset indent
mount -a -t nonfs,mfs
.Ed
.Pp
mounts all filesystems except those of type
.Tn NFS
and
.Tn MFS .
.Pp
If the type is not one of the internally known types,
mount will attempt to execute a program in
.Pa /sbin/mount_ Ns Em XXX
where
.Em XXX
is replaced by the type name.
.It Fl u
The
.Fl u
flag indicates that the status of an already mounted file
system should be changed.
Any of the options discussed above (the
.Fl o
option)
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 system from the
.Xr fstab
table,
then applying any options specified by the
.Fl o
argument,
and finally applying the
.Fl r
or
.Fl w
option.
.It Fl v
Verbose mode.
.It Fl w
The file system object is to be read and write.
.It Fl
Any additional options specific to the program can
be passed as a comma separated list;
these options are distinguished by starting with a
.Fl
(dash).
.El
.Pp
Those options that take a value are specified
using the syntax -option=value.
For example, the mount command:
.Bd -literal -offset indent
mount -t mfs -o nosuid,-N,-s=4000 /dev/dk0b /tmp
.Ed
.Pp
causes mount to attempt to execute:
.Bd -literal -offset indent
/sbin/mount_mfs -F 8 -N -s 4000 /dev/dk0b /tmp
.Ed
.Pp
The following list can be used to override
the defaults for an nfs mount:
.Bl -tag -width indent
.It hard
.Tn I/O
system calls will retry until the server responds (default)
.It soft
.Tn I/O
system calls will fail and return errno after
.Em retrans
request
retransmissions
.It 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.
.It bg
If the first mount request times out, do retries in background
.It intr
.Tn I/O
system calls can be interrupted.
.It noconn
Do not connect the socket.
Used for
.Tn UDP
servers that send replies from a
socket other than the nfs server socket.
.It tcp
Use
.Tn TCP
transport instead of
.Tn UDP .
.It rsize=#
Set read size to
.Ar #
bytes.
.It wsize=#
Set write size to
.Ar #
bytes.
.It retry=#
Set mount retry count to
.Ar # .
.It retrans=#
Set retransmission count for nfs rpc's to
.Ar # .
.It timeo=#
Set initial nfs timeout to
.Ar #
in 0.1 sec intervals.
.El
.Pp
.Nm Umount
removes the
.Ar special
device
grafted
at point
.Ar node
from file system tree.
.Pp
Options for the
.Nm umount
command:
.Bl -tag -width indent
.It Fl f
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.
.It Fl a
All of the file systems described in
.Xr fstab
are unmounted.
.It Fl t
Is used to indicate 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.
(See example above for the
.Nm mount
command.)
.El
.Sh FILES
.Bl -tag -width /etc/fstab -compact
.It Pa /etc/fstab
file system table
.El
.Sh SEE ALSO
.Xr mount 2 ,
.Xr unmount 2 ,
.Xr fstab 5
.Sh BUGS
It is possible for a corrupted file system to cause a crash.
.Sh HISTORY
A
.Nm
command appeared in
.At v6 .