MOUNT(8) BSD System Manager's Manual MOUNT(8)
mount -- mount file systems
mount [-adfruvw] [-t ufs | lfs | external_type]
mount [-dfruvw] special | node
mount [-dfruvw] [-o options] [-t ufs | lfs | external_type] special node
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)
The system maintains a list of currently mounted file systems. If no arguments are given to
mount, this list is printed.
The options are as follows:
-a All the filesystems described in fstab(5) are mounted. Exceptions are those marked
as ``noauto'' or are excluded by the -t flag (see below).
-d Causes everything to be done except for the actual system call. This option is use-
ful in conjunction with the -v flag to determine what the mount command is trying to
-f Forces the revocation of write access when trying to downgrade a filesystem mount
status from read-write to read-only.
-o Options are specified with a -o flag followed by a comma separated string of
options. The following options are available:
async All I/O to the file system should be done asynchronously. This can be some-
what dangerous with respect to losing data when faced with system crashes
and power outages. This is also the default. It can be avoided with the
force The same as -f; forces the revocation of write access when trying to down-
grade a filesystem mount status from read-write to read-only.
This filesystem should not force all I/O to be written asynchronously.
noauto This filesystem should be skipped when mount is run with the -a flag.
nodev Do not interpret character or block special devices on the file system.
This option is useful for a server that has file systems containing special
devices for architectures other than its own.
noexec Do not allow execution of any binaries on the mounted file system. This
option 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
rdonly The same as -r; mount the file system read-only (even the super-user may not
sync All I/O to the file system should be done synchronously.
update The same as -u; indicate that the status of an already mounted file system
should be changed.
union Causes the namespace at the mount point to appear as the union of the
mounted filesystem root and the existing directory. Lookups will be done in
the mounted filesystem first. If those operations fail due to a non-exis-
tent file the underlying directory is then accessed. All creates are done
in the mounted filesystem.
Any additional options specific to a filesystem type that is not one of the inter-
nally known types (see the -t option) may be passed as a comma separated list; these
options are distinguished by a leading ``-'' (dash). Options that take a value are
specified using the syntax -option=value. For example, the mount command:
mount -t hfs -o nosuid,-w,-m=755 /dev/disk2s9 /tmp
causes mount to execute the equivalent of:
/sbin/mount_hfs -o nosuid -w -m 755 /dev/disk2s9 /tmp
-r The file system is to be mounted read-only. Mount the file system read-only (even
the super-user may not write it). The same as the ``rdonly'' argument to the -o
-t ufs | lfs | external type
The argument following the -t is used to indicate the file system type. The type
ufs is the default. The -t option can be used to indicate that the actions should
only be taken on filesystems of the specified type. More than one type may be spec-
ified in a comma separated list. The list of filesystem types can be prefixed with
``no'' to specify the filesystem types for which action should not be taken. For
example, the mount command:
mount -a -t nonfs,hfs
mounts all filesystems except those of type NFS and HFS.
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. For example,
nfs filesystems are mounted by the program /sbin/mount_nfs.
-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 or vice versa. An attempt
to change from read-write to read-only will fail if any files on the filesystem are
currently open for writing unless the -f flag is also specified. The set of options
is determined by first extracting the options for the file system from the fstab ta-
ble, 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.
The options specific to NFS filesystems are described in the mount_nfs(8) manual
/etc/fstab file system table
mount(2), fstab(5), mount_afp(8), mount_cd9660(8), mount_cddafs(8), mount_devfs(8),
mount_fdesc(8), mount_hfs(8), mount_msdos(8), mount_nfs(8), mount_smbfs(8),
mount_synthfs(8), mount_udf(8), mount_volfs(8), mount_webdav(8), umount(8)
It is possible for a corrupted file system to cause a crash.
A mount command appeared in Version 6 AT&T UNIX.
4th Berkeley Distribution June 16, 1994 4th Berkeley Distribution