MOUNT

Section: Maintenance Commands (8)
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BSD mandoc
BSD 4

NAME

mount umount - mount and dismount file systems

SYNOPSIS

DESCRIPTION

The mount command calls the mount(2) system call to prepare and graft a special device or the remote node (rhost:path) on to the file system tree at the point node. If either special or node are not provided, the appropriate information is taken from the fstab(5) file.

The system maintains a list of currently mounted file systems. If no arguments are given to mount, this list is printed.

Options available for the mount command:

-F

The standard mount options are parsed and passed to external program via the -F option as a decimal number. (See example below.)

-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 -v flag to determine what the mount command is trying to do.

-o

Options are specified with a -o flag 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.

-r

The file system object is to be mounted read-only.

-t nfs \*(Ba ufs \*(Ba external type

The argument following the -t is used to indicate the file system type. The type ufs is the default. For example, the mount command:

mount -a -t nonfs,mfs

mounts all filesystems except those of type NFS and MFS

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.

-u

The -u flag indicates that the status of an already mounted file system should be changed. Any of the options discussed above (the -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 fstab table, then applying any options specified by the -o argument, and finally applying the -r or -w option.

-v

Verbose mode.

-w

The file system object is to be read and write.

-

Any additional options specific to the program can be passed as a comma separated list; these options are distinguished 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

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 background
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 removes the special device grafted at point node from file system tree.

Options for the umount command:

-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.
-a: All of the file systems described in fstab are unmounted.
-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 mount command.)

FILES

/etc/fstab: file system table

BUGS

It is possible for a corrupted file system to cause a crash.

HISTORY

A mount command appeared in AT&T System v6 .

This document was created by man2html, using the manual pages.
Time: 06:35:22 GMT, May 19, 2025