mount(1M)

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | DIAGNOSTICS | FILES | ATTRIBUTES | SEE ALSO | BUGS | CAVEATS

NAME

mount- mount file systems

SYNOPSIS

mount [-adfpruvw] [[-t ufs ]| [lfs]| [external_type]]
mount [-dfpruvw] [[special]| [node]]
mount [-dfpruvw] [-o options] [[-t ufs]| [lfs]| [external_type]] [special node]

DESCRIPTION

The mount command is available as a C_INIT(1M) built-in command. In this case, the configuration of the ADMIN_MOUNT feature is required. The mount command calls the mount(2POSIX) system call to prepare and graft a remote node (rhost:path) or special_device onto the file system tree at the point node. If either special or node are not provided, the appropriate information is taken from the fstab(4CC) file.

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

OPTIONS

The options are as follows:

-a

All the filesystems described in fstab(4CC) are mounted. Exceptions are those marked as ``noauto'', excluded by the -t flag (see below), or if they are already mounted (except the root filesystem which is always remounted to preserve traditional single user mode behavior).

-d

Causes everything to be done except for the actual system call. This option is useful in conjunction with the -v flag to determine what the mount command is trying to do.

-f

Forces the revocation of write access when trying to downgrade a filesystem mount status from read-write to read-only. Also forces the R/W mount of an unclean filesystem (dangerous; use with caution).

-o

Options are specified with a -o flag followed by a comma separated string of options. In case of conflicting options being specified, the rightmost option takes effect. The following options are available:

async

All I/O to the file system should be done asynchronously. This is a dangerous option to use, and should not be used unless you are prepared to recreate the file system in the event of a system crash.

current

When used with the -u flag, this is the same as specifying the options currently in effect for the mounted filesystem.

force

The same as -f; forces the revocation of write access when trying to downgrade a filesystem mount status from read-write to read-only. Also forces the R/W mount of an unclean filesystem (dangerous; use with caution.

fstab

When used with the -u flag, this is the same as specify ing all the options listed in the fstab(4CC) file for the filesystem.

noasync

Metadata I/O should be done synchronously, while data I/O should be done asynchronously. This is the default.

noatime

Do not update the file access time when reading from a file. This option is useful on filesystems where there are large numbers of files and performance is more critical than updating the file access time (which is rarely important. This option is currently only supported on local filesystems.

noauto

This filesystem should be skipped when mount is run with the -a flag.

noclusterr

Disable read clustering.

noclusterw

Disable write clustering.

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 effect. Note: This option is worthless if a publicly available suid or sgid wrapper like suidperl is installed on your system.

nosymfollow

Do not follow symlinks on the mounted file system.

rdonly

The same as -r; mount the file system read-only (even the superuser may not write it).

sync

All I/O to the file system should be done synchronously.

suiddr

A directory on the mounted filesystem will respond to the SUID bit being set, by setting the owner of any new files to be the same as the owner of the directory. New directories will inherit the bit from their parents. Execute bits are removed from the file, and it will not be given to root.

This feature is designed for use on fileservers serving PC users via ftp, SAMBA, or netatalk. It provides security holes for shell users and as such should not be used on shell machines, especially on home directories. This option requires the SUIDDIR option in the microkernel to work. Only UFS filesystems support this option. See chmod(2POSIX) for more information.

update

Indicates 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-existent 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 internally 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 mfs -o nosuid,-N,-s=4000 /dev/dk0b /tmp

causes mount to execute the equivalent of:

/sbin/mount_mfs -o nosuid -N -s 4000 /dev/dk0b /tmp

p

Print mount information in fstab(4CC) format. Implies also the -v option.

r

The file system is to be mounted read-only. Mount the file system read-only (even the superuser may not write it). The same as the "rdonly" argument to the -o option.

-t ufs | lfs | external_type

The argument following the -t option 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 specified 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,nomfs

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. For example, NFS filesystems are mounted by the program /sbin/mount_nfs.

Most filesystems will be dynamically loaded by their mount programs if not already present in the microkernel. Because this mechanism requires writable temporary space, the filesystem type containing /tmp must be compiled into the microkernel, and the filesystems containing /tmp and /usr/bin/ld must be listed in /etc/fstab before any filesystems which might be dynamically loaded.

-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) can 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 file system are currently open for writing unless the -f flag is also specified. The set of options is determined by applying the options specified in the argument to -o 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(1M) manual page.

DIAGNOSTICS

Various, most of them are self-explanatory.

---

XXXXXfilesystem not available

---

The microkernel does not support the respective filesystem type. Note that support for a particular filesystem might be provided either on a static (kernel compile-time), or dynamic basis. Normally, mount or its subprocesses attempt to dynamically load a filesystem module if it has not been configured statically In this case, the above error message can also mean that you did not have permission to load the module.

FILES

/etc/fstab file system table

ATTRIBUTES

See attributes(5) for descriptions of the following attributes:

ATTRIBUTE TYPE	ATTRIBUTE VALUE
Interface Stability	Evolving

SEE ALSO

mount(2POSIX), fstab(4CC), mount_msdos(1M), mount_nfs(1M), umount(1M), chmod(2POSIX)

BUGS

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

CAVEATS

After a successful mount, the permissions on the original mount point determine if .. is accessible from the mounted file system. The minimum permissions for the mount point for traversal across the mount point in both directions to be possible for all users is 0111 (execute for all).

ChorusOS 5.0  Last Revised December 2001

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | DIAGNOSTICS | FILES | ATTRIBUTES | SEE ALSO | BUGS | CAVEATS