Udisks - ArchWiki

# Udisks

Related articles

- udev
- Mount
- Polkit
- File manager functionality

udisks provides a daemon udisksd, that implements D-Bus interfaces used to query and manipulate storage devices, and a command-line tool udisksctl, used to query and use the daemon.

## Installation

There are two versions of udisks called udisks and udisks2. Development of udisks has ceased in favor of udisks2. [1]

udisksd (udisks2) and udisks-daemon (udisks) are started on-demand by D-Bus, and should not be enabled explicitly (see `man udisksd` and `man udisks-daemon`). They can be controlled through the command-line with udisksctl and udisks, respectively. See `man udisksctl` and `man udisks` for more information.

## Configuration

Actions a user can perform using udisks are restricted with Policykit. If your session is not activated or present, configure policykit manually. The following file sets common udisks permissions for the `storage` group. [2]

    /etc/polkit-1/rules.d/50-udisks.rules

    polkit.addRule(function(action, subject) {
      var YES = polkit.Result.YES;
      var permission = {
        // only required for udisks1:
        "org.freedesktop.udisks.filesystem-mount": YES,
        "org.freedesktop.udisks.filesystem-mount-system-internal": YES,
        "org.freedesktop.udisks.luks-unlock": YES,
        "org.freedesktop.udisks.drive-eject": YES,
        "org.freedesktop.udisks.drive-detach": YES,
        // only required for udisks2:
        "org.freedesktop.udisks2.filesystem-mount": YES,
        "org.freedesktop.udisks2.filesystem-mount-system": YES,
        "org.freedesktop.udisks2.encrypted-unlock": YES,
        "org.freedesktop.udisks2.eject-media": YES,
        "org.freedesktop.udisks2.power-off-drive": YES,
        // required for udisks2 if using udiskie from another seat (e.g. systemd):
        "org.freedesktop.udisks2.filesystem-mount-other-seat": YES,
        "org.freedesktop.udisks2.encrypted-unlock-other-seat": YES,
        "org.freedesktop.udisks2.eject-media-other-seat": YES,
        "org.freedesktop.udisks2.power-off-drive-other-seat": YES
      };
      if (subject.isInGroup("storage")) {
        return permission[action.id];
      }
    });

See [3] for a more restrictive example. Note the `org.freedesktop.udisks2.filesystem-*` settings, which are required to start udiskie from a systemd service.

## Mount helpers

Automatic mounting of devices is easily achieved with udisks wrappers. See also List of applications#Mount tools and File manager functionality#Mounting.

### Devmon

udevil includes devmon, which is compatible to udisks and udisks2. It uses mount helpers with the following priority:

1. udevil (SUID)
2. pmount (SUID)
3. udisks
4. udisks2

To mount devices with udisks or udisks2, remove the SUID permission from udevil:

    # chmod -s /usr/bin/udevil

Note: `chmod -x /usr/bin/udevil` as root causes devmon to use udisks for device monitoring
Tip: To run devmon in the background and automatically mount devices, enable it with `devmon@.service`, taking the user name as argument: `devmon@user.service`. Keep in mind services run outside the session. Adjust Polkit rules where appropriate, or run `devmon` from the user session (see Autostart).

### inotify

You may use inotify-tools to monitor `/dev`, and mount drives when a new block device is created. Stale mount points are automatically removed by udisksd, such that no special action is required on deletion.

    #!/bin/bash
    inotifywait --monitor --event create,delete --format '%e %w%f' /dev | while read event file; do
        pattern='sd[b-z][1-9]$'
        if [[ $file =~ $pattern ]]; then
    	case $event in
    	    CREATE)
    		echo "Settling..."
    		sleep 1
    		udisksctl mount --block-device $file --no-user-interaction
    		;;
    	    DELETE)
    		;;
    	esac
        fi
    done

## Tips and tricks

### Disable hiding of devices (udisks2)

Udisks2 hides certain devices from the user by default. If this is undesired or otherwise problematic, copy `/usr/lib/udev/rules.d/80-udisks2.rules` to `/etc/udev/rules.d/80-udisks2.rules` and remove the following section in the copy:

    # ------------------------------------------------------------------------
    # ------------------------------------------------------------------------
    # ------------------------------------------------------------------------
    # Devices which should not be display in the user interface
    [...]

### Mount to /media (udisks2)

By default, udisks2 mounts removable drives under the ACL controlled directory `/run/media/$USER/`. If you wish to mount to `/media` instead, use this rule:

    /etc/udev/rules.d/99-udisks2.rules

    # UDISKS_FILESYSTEM_SHARED
    # ==1: mount filesystem to a shared directory (/media/VolumeName)
    # ==0: mount filesystem to a private directory (/run/media/$USER/VolumeName)
    # See udisks(8)
    ENV{ID_FS_USAGE}=="filesystem|other|crypto", ENV{UDISKS_FILESYSTEM_SHARED}="1"

### Mount an ISO image

To easily mount ISO images, use the following command:

    $ udisksctl loop-setup -r -f image.iso

This will create a loop device and show the ISO image ready to mount. Once unmounted, the loop device will be terminated by udev.

### Hide selected partitions

If you wish to prevent certain partitions or drives appearing on the desktop, you can create a udev rule, for example `/etc/udev/rules.d/10-local.rules`:

    KERNEL=="sda1", ENV{UDISKS_PRESENTATION_HIDE}="1"
    KERNEL=="sda2", ENV{UDISKS_PRESENTATION_HIDE}="1"

shows all partitions with the exception of `sda1` and `sda2` on your desktop. Notice if you are using udisks2 the above will not work as `UDISKS_PRESENTATION_HIDE` is no longer supported. Instead use `UDISKS_IGNORE` as follows:

    KERNEL=="sda1", ENV{UDISKS_IGNORE}="1"
    KERNEL=="sda2", ENV{UDISKS_IGNORE}="1"

## Troubleshooting

### udisks: Devices do not remain unmounted

udisks remounts devices after a given period, or polls those devices. This can cause unexpected behaviour, for example when formatting drives, sharing them in a virtual machine, power saving, or removing a drive that was not detached with `--detach` before.

To disable polling for a given device, for example a CD/DVD device:

    # udisks --inhibit-polling /dev/sr0

or for all devices:

    # udisks --inhibit-all-polling

See `man udisks` for more information.

## See also

- gentoo wiki: udisks
- Introduction to udisks

Category:

- Hardware detection and troubleshooting