udisks(8) - Disk Manager



  • UDISKS(8)		     System Administration		     UDISKS(8)
    
    NAME
           udisks - Disk Manager
    
    DESCRIPTION
           udisks provides interfaces to enumerate and perform operations on disks
           and storage devices. Any application (including unprivileged ones) can
           access the udisksd(8) daemon via the name org.freedesktop.UDisks2 on
           the system message bus[1]. In addition to the D-Bus API, a library,
           libudisks2 is also provided. This library can be used from C/C++ and
           any high-level language with GObjectIntrospection[2] support such as
           Javascript and Python. udisks is only indirectly involved in what
           devices and objects are shown in the user interface. See these notes[3]
           for what is shown in GNOME 3.
    
    ACCESS CONTROL
           By default, logged-in users in active log-in sessions are permitted to
           perform operations (for example, mounting, unlocking or modifying) on
           devices attached to the seat their session is on. Access-control is
           fine-grained and based on polkit(8), see the “Authorization Checks”
           chapter in the udisks documentation for more information. Note that the
           x-udisks-auth option can be used in the /etc/fstab and /etc/crypttab
           files to specify that additional authorization is required to mount
           resp. unlock the device (typically requiring the user to authenticate
           as an administrator).
    
    DRIVE CONFIGURATION
           At start-up and when a drive is connected, udisksd(8) will apply
           configuration stored in the file /etc/udisks2/IDENTIFIER.conf where
           IDENTIFIER is the value of the Drive:Id property for the drive. If the
           file changes on disk its new contents will also be applied to the
           drive. Typically, users or administrators will never need to edit drive
           configuration files as they are effectively managed through graphical
           applications such as gnome-disks(1). Manually editing configuration
           files is however supported — the file format is a simple .ini-like
           format (see the Desktop Entry Specification[4] for the exact syntax).
           New groups and keys may be added in the future.
    
       ATA group
           The ATA group is for settings that apply to drives using the ATA
           command-set. The following keys are supported:
    
           StandbyTimeout
    	   The standby timeout. A value of zero means "timeouts are disabled":
    	   the device will not automatically enter standby mode. Values from 1
    	   to 240 specify multiples of 5 seconds, yielding timeouts from 5
    	   seconds to 20 minutes. Values from 241 to 251 specify from 1 to 11
    	   units of 30 minutes, yielding timeouts from 30 minutes to 5.5
    	   hours. A value of 252 signifies a timeout of 21 minutes. A value of
    	   253 sets a vendor-defined timeout period between 8 and 12 hours,
    	   and the value 254 is reserved. 255 is interpreted as 21 minutes
    	   plus 15 seconds. Note that some older drives may have very
    	   different interpretations of these values. This is similar to the
    	   -S option in hdparm(8).
    
           APMLevel
    	   The Advanced Power Management level. A low value means aggressive
    	   power management and a high value means better performance.
    	   Possible settings range from values 1 through 127 (which permit
    	   spin-down), and values 128 through 254 (which do not permit
    	   spin-down). The highest degree of power management is attained with
    	   a setting of 1, and the highest I/O performance with a setting of
    	   254. A value of 255 can be used to disable Advanced Power
    	   Management altogether on the drive (not all drives support
    	   disabling it, but most do). This is similar to the -B option in
    	   hdparm(8).
    
           AAMLevel
    	   The Automatic Acoustic Management level. Most modern harddisk
    	   drives have the ability to speed down the head movements to reduce
    	   their noise output. The possible values are between 0 and 254. 128
    	   is the most quiet (and therefore slowest) setting and 254 the
    	   fastest (and loudest). Some drives have only two levels (quiet /
    	   fast), while others may have different levels between 128 and 254.
    	   At the moment, most drives only support 3 options, off, quiet, and
    	   fast. These have been assigned the values 0, 128, and 254 at
    	   present, respectively, but integer space has been incorporated for
    	   future expansion, should this change. This is similar to the -M
    	   option in hdparm(8).
    
           WriteCacheEnabled
    	   A boolean specifying whether to enable or disable the Write Cache.
    	   Valid values for this key are “true” and “false”. This is similar
    	   to the -W option in hdparm(8). This key was added in 2.1.
    
           ReadLookaheadEnabled
    	   A boolean specifying whether to enable or disable the Read
    	   Look-ahead. Valid values for this key are “true” and “false”. This
    	   is similar to the -A option in hdparm(8). This key was added in
    	   2.1.7.
    
    DEVICE INFORMATION
           udisks relies on recent versions of udev(7) and the Linux kernel.
           Influential device properties in the udev database include:
    
           UDISKS_SYSTEM
    	   If set, this overrides the value of the HintSystem property.
    
           UDISKS_IGNORE
    	   If set, this overrides the value of the HintIgnore property.
    
           UDISKS_AUTO
    	   If set, this overrides the value of the HintAuto property.
    
           UDISKS_CAN_POWER_OFF
    	   If set, this overrides the value of the CanPowerOff property.
    
           UDISKS_NAME
    	   The name to use for the device when presenting it in an user
    	   interface. This corresponds to the HintName property.
    
           UDISKS_ICON_NAME
    	   The icon to use for the device when presenting it in an user
    	   interface. If set, the name must adhere to the freedesktop.org icon
    	   theme specification[5]. This corresponds to the HintIconName
    	   property.
    
           UDISKS_SYMBOLIC_ICON_NAME
    	   The icon to use for the device when presenting it in an user
    	   interface using a symbolic icon. If set, the name must adhere to
    	   the freedesktop.org icon theme specification[5]. This corresponds
    	   to the HintSymbolicIconName property.
    
           UDISKS_FILESYSTEM_SHARED
    	   If set to 1, the filesystem on the device will be mounted in a
    	   shared directory (e.g.  /media/VolumeName) instead of a private
    	   directory (e.g.  /run/media/$USER/VolumeName) when the
    	   Filesystem.Mount() method is handled.
    
           ID_SEAT
    	   The physical seat the device is attached to. If unset or set to the
    	   empty string, “seat0” (the first seat) is assumed.
    
    API STABILITY
           udisks guarantees a stable D-Bus API within the same major version and
           this guarantee also extends to the client-side library libudisks2.
           Additionally, several major versions of udisks can be installed and
           operate at the same time although interoperability may be limited - for
           example, a device mounted using the udisks N.x API may require
           additional authorization if attempting to unmount it through the the
           (N-1).x API.
    
           The udisks developers do not anticipate breaking API but does reserve
           the right to do so and if it happens, promises to bump the major
           version and ensure the new major version of udisks is
           parallel-installable with any older major version. However, note that
           programs, man pages and other artifacts may change name (for example,
           adopt a “2” suffix) to make room for the next major version. Therefore,
           applications can not rely on tools like e.g.  udisksctl(1) to be
           available. Additionally, there is no guarantee that the options,
           command-line switches etc. of command-line tools or similar will remain
           stable.
    
           Instead, applications should only use the D-Bus API, the libudisks2
           library or tools such as dbus-send(1) or gdbus(1) to interact with
           udisksd(8).
    
    AUDIENCE
           The intended audience of udisks include operating system developers
           working on the higher-level parts of the operating system, for example
           the desktop shell (such as GNOME[6]) and disk management applications
           (e.g. GNOME's Disks[7] application). Software on this level typically
           depend on a specific (major) version of udisks and may even have
           support for previous versions of udisks or alternative interfaces
           performing the same role as udisks.
    
           While udisks indeed provides a stable API and a clear upgrade path, it
           may not be an appropriate dependency for third party applications. For
           example, if the operating system switches to udisks version N.x and an
           application is still using the udisks (N-1).x API, the application will
           not work unless udisks (N-1).x is installed. While this situation is
           still workable (since both udisks N.x and udisks (N-1).x can be
           installed) it may not be desirable to ask the user to install the old
           version - in fact, the operating system vendor may not even provide a
           packaged version of the old version. Hence, if an application does not
           want to tie itself to a specific version of the operating system, it
           should not use udisks.
    
           Viable alternatives to udisks are APIs that are guaranteed to be around
           for longer time-frames, including:
    
           ·   Low-level APIs and commands such as e.g.  sysfs[8], libudev[9],
    	   /proc/self/mountinfo[10] and util-linux[11].
    
           ·   High-level APIs such as GVolumeMonitor[12].
    
           In particular, for desktop applications it is a much better idea to use
           something like GVolumeMonitor since it will make the application show
           the same devices as the desktop shell (e.g. file manager, file chooser
           and so on) is showing.
    
    AUTHOR
           Written by David Zeuthen <[email protected]> with a lot of help from
           many others.
    
    BUGS
           Please send bug reports to either the distribution bug tracker or the
           upstream bug tracker at
           http://bugs.freedesktop.org/enter_bug.cgi?product=udisks.
    
    SEE ALSO
           udev(7), polkit(8), udisksd(8), udisksctl(1), umount.udisks2(8), gnome-
           disks(1)
    
    NOTES
    	1. system message bus
    	   http://www.freedesktop.org/wiki/Software/dbus
    
    	2. GObjectIntrospection
    	   https://live.gnome.org/GObjectIntrospection
    
    	3. notes
    	   http://git.gnome.org/browse/gvfs/tree/monitor/udisks2/what-is-shown.txt
    
    	4. Desktop Entry Specification
    	   http://freedesktop.org/wiki/Specifications/desktop-entry-spec
    
    	5. freedesktop.org icon theme specification
    	   http://www.freedesktop.org/wiki/Specifications/icon-theme-spec
    
    	6. GNOME
    	   http://www.gnome.org
    
    	7. Disks
    	   https://live.gnome.org/Design/Apps/Disks
    
    	8. sysfs
    	   http://en.wikipedia.org/wiki/Sysfs
    
    	9. libudev
    	   http://www.freedesktop.org/software/systemd/libudev/
    
           10. /proc/self/mountinfo
    	   http://www.kernel.org/doc/Documentation/filesystems/proc.txt
    
           11. util-linux
    	   http://en.wikipedia.org/wiki/Util-linux
    
           12. GVolumeMonitor
    	   http://developer.gnome.org/gio/stable/volume_mon.html
    
    udisks 2.1.7			  March 2013			     UDISKS(8)
    


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