mount
Related articles
mount is an application used to access file systems, partition tables, and shared folders. It can mount file systems supported by the Linux kernel, but can be extended with other drivers or applications, such as ntfs-3g for mounting NTFS filesystems. See mount(8).
Contents
Usage
The fstab file may contain lines describing what devices are usually mounted where, using which options. A file system specified in /etc/fstab
will be mounted at boot time, with some exceptions. For example, any device whose line contains the noauto
option will not be mounted. This is useful for things like partitions for other OSes.
External devices that are to be mounted when present, but ignored if absent, may require the nofail
option. See external devices for more information.
When mounting a file system mentioned in fstab or mtab, it is sufficient to give only the device, or only the mount point. For example, to mount /dev/sdb1
:
# mount /dev/sdb1
The mount program does not read the /etc/fstab
file if device (or LABEL/UUID) and directory (mount point) are specified. For example:
# mount /dev/sdb1 /mnt/mydir
If the mount point does not exist, it may be necessary to create it first. For example:
# mkdir /mnt/mydir # mount /dev/sdb1 /mnt/mydir
Listing mounted file systems
Mounted file systems are visible from /etc/mtab, which is a symbolic link to /proc/self/mounts
. See also findmnt(8).
The /etc/mtab is a system-generated file created and updated by the mount application whenever any file system is mounted or unmounted.
Whenever the mount
program is executed without any arguments, this file is printed. Each line in the file represents a file system that is currently mounted and displays the following information:
- device node
- mount point
- file system type
- Mount options used while mounting the file system.
Alternatives to change the default mount options
A few examples about how to extend mount functionality and modify default options:
- By editing fstab to include the desired mount options
- By creating udev / udisks rules - mostly useful for removable devices
- Mounting manually / by using scripts
- The mount.X scripts or symbolic links, where X is the name of a file system, can be used to alter the default mount options for almost any of its supported file systems. Option
-i
is used to let the mount command ignore mount.X scripts and must also be used inside mount.X scripts for any mount command. - There are two ways to list the available scripts:
- Write mount and press a
Tab
key. - Execute
ls /usr/bin/mount.*
.
- Write mount and press a
- To change the default settings in the kernel, you will need to compile it yourself.
Some other file systems
VFAT, FAT, DOS
Here is an example of the default mount configuration in the kernel:
$ zgrep -e FAT -e DOS /proc/config.gz | sort -r
# DOS/FAT/NT Filesystems CONFIG_FAT_FS=m CONFIG_MSDOS_PARTITION=y CONFIG_FAT_FS=m CONFIG_MSDOS_FS=m CONFIG_VFAT_FS=m CONFIG_FAT_DEFAULT_CODEPAGE=437 CONFIG_FAT_DEFAULT_IOCHARSET="iso8859-1" CONFIG_NCPFS_SMALLDOS=y
A short description of the options:
- Language settings: CONFIG_FAT_DEFAULT_CODEPAGE, CONFIG_FAT_DEFAULT_IOCHARSET
- All filenames to lower letters on a FAT partitions if enabled: CONFIG_NCPFS_SMALLDOS
- Enables support of the FAT file systems: CONFIG_FAT_FS, CONFIG_MSDOS_FS, CONFIG_VFAT_FS
- Enables support of a FAT partitioned harddisks on 86x PCs: CONFIG_MSDOS_PARTITION
If the partition type detected by mount is VFAT then it will run the /usr/bin/mount.vfat
script.
/usr/bin/mount.vfat
#!/bin/bash #mount VFAT with full rw (read-write) permissions for all users #/usr/bin/mount -i -t vfat -oumask=0000,iocharset=utf8 "$@" #The above is the same as mount -i -t vfat -oiocharset=utf8,fmask=0000,dmask=0000 "$@"
See also: more details about mounting of the FAT file systems.
NTFS
The default configuration:
$ zgrep ^CONFIG_NTFS /proc/config.gz
CONFIG_NTFS_FS=m CONFIG_NTFS_RW=y
The kernel config option CONFIG_NTFS_RW=y
enables read-write support for NTFS file systems. It also means the kernel is predefined to use the ntfs-3g driver in read-write mode. The build in support of the NTFS file systems by the kernel is read-only even if read-write is activated by an option.
The default mount options can be altered when running mount.ntfs
by renaming the /usr/bin/mount.ntfs
symlink if exists and creating a script in its place with a preferred options or use the -i option (mount -i -t ntfs
) to ignore all the mount.X files and use the natively supported functionality by the kernel. This example will mount NTFS as a read-only:
/usr/bin/mount.ntfs
#!/bin/bash #mount -i -oro "$@" #mount with a read-only rights ntfs-3g -oro "$@" & disown
See man 8 ntfs-3g
for more information about the ntfs-3g driver.
You can add more actions for when an external storage device, such as a USB drive or image file (ISO, img, dd), is mounted by using scripts.
See also
- Documentation of file systems supported by kernel: kernel.org
- Wikipedia:Mount (Unix)
- Creating and using disk images mini-howto: darkdust.net