udisks

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

Install the udisks2 package.

udisksd(8) is started on-demand by D-Bus and should not be enabled explicitly. It can be controlled through the command-line with udisksctl(1).

Configuration

Permissions

Actions a user can perform using udisks are restricted with polkit. If the user session is not activated or present (for example, when controlling udisks from a systemd/User service), adjust polkit rules accordingly.

See https://github.com/coldfix/udiskie/wiki/Permissions for common udisks permissions for the storage group, and [1] for a more restrictive example. If you are using Dolphin, you may see [2].

Default mount options

It is possible to define default mount options in /etc/udisks2/mount_options.conf. Create the file if it does not already exist. The built-in defaults and some examples can be seen in /etc/udisks2/mount_options.conf.example.[3]

The options can target specific filesystem types. For example, mount btrfs filesystems with zstd compression enabled:

/etc/udisks2/mount_options.conf

[defaults]
btrfs_defaults=compress=zstd

Note: Lines override the corresponding built-in defaults. Make sure not to accidentally remove mount options this way.

Usage

To manually mount a removable drive, for example /dev/sdc:

$ udisksctl mount -b /dev/sdc1

To unmount:

$ udisksctl unmount -b /dev/sdc1

See udisksctl help for more.

Tips and tricks

Mount helpers

The automatic mounting of devices is easily achieved with udisks wrappers. See also List of applications/Utilities#Mount tools.

Note: Desktop environments, such as GNOME and Plasma may also provide a udisks wrapper.

bashmount — A bash script to mount and manage removable media as a regular user.

https://github.com/jamielinux/bashmount || bashmount^AUR

dolphin-plugins — uses udisksctl to either mount or unmount the iso in Dolphin.

https://apps.kde.org/dolphin_plugins/ || dolphin-plugins

udiskie — Automounter with optional notifications, tray icon and support for password protected LUKS devices. See the udiskie wiki for details

https://github.com/coldfix/udiskie || udiskie

udiskie-dmenu — dmenu interface for udiskie.

https://github.com/fogine/udiskie-dmenu || udiskie-dmenu-git^AUR

udisksvm — GUI wrapper written in Python3 and using the Qt5 framework. It uses mouse clicks to mount, unmount removable devices or eject a CD/DVD. See the README file for details.

https://github.com/berbae/udisksvm || udisksvm^AUR

udevil — Includes devmon.

https://github.com/IgnorantGuru/udevil || udevil^AUR

Note: devmon only uses udisks2 for mounting (in this order) if udevil or pmount miss the SUID permission. To remove this permission, run chmod -s /usr/bin/udevil as root.

udevadm monitor

You may use udevadm monitor to monitor block events 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/sh

pathtoname() {
    udevadm info -p /sys/"$1" | awk -v FS== '/DEVNAME/ {print $2}'
}

stdbuf -oL -- udevadm monitor --udev -s block | while read -r -- _ _ event devpath _; do
        if [ "$event" = add ]; then
            devname=$(pathtoname "$devpath")
            udisksctl mount --block-device "$devname" --no-user-interaction
        fi
done

Mount to /media

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"

Since /media, unlike /run, is not mounted by default as a tmpfs, you may also wish to create a tmpfiles.d snippet to clean stale mountpoints at every boot:

/etc/tmpfiles.d/media.conf

D /media 0755 root root 0 -

Mount loop devices

To easily mount ISO images, use the following command:

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

This will create a read only loop device and show the ISO image ready to mount. Remove the -r flag to be able to write to it. The name of the created loop device is output by the above loop-setup command.

You can unmount, and remount, the image as long as the specific loop device is in place. When done working with the specific loop device, use

$ udisksctl loop-delete -b /dev/loop0

to delete it. Substitute /dev/loop0 with the name of the specific loop device.

Loop devices are cheap. Therefore, many loop devices can be created in practice without worrying about a denial of service issue. See [4].

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

shows all partitions with the exception of sda1 and sda2 on your desktop.

Because block device names can change between reboots, it is also possible to use UUIDs to hide partitions or whole devices. Matching by UUID is only possible after /usr/lib/udev/rules.d/60-persistent-storage.rules has been processed, so make sure to choose a file name that will be ordered after it. For example:

/etc/udev/rules.d/61-hide-partitions.rules

SUBSYSTEM=="block", ENV{ID_FS_UUID}=="XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXXX", ENV{UDISKS_IGNORE}="1"

The above line is also useful to hide multi device btrfs filesystems, as all the devices from a single btrfs filesystem will share the same UUID across the devices but will have different SUB_UUID for each individual device.

Apply ATA settings

At start-up and when a drive is connected, udisksd will apply configuration stored in the file /etc/udisks2/IDENTIFIER.conf where IDENTIFIER is the value of the Drive:Id property for the drive. Currently ATA settings are supported. See udisks(8) for available options. These settings have essentially the same effect as those of hdparm, but they are persistent as long as the udisks daemon is autostarted.

For example, to set standby timeout to 240 (20 minutes) for a drive, add the following:

/etc/udisks2/DriveId.conf

[ATA]
StandbyTimeout=240

To obtain the DriveId for your drive, use udevadm info --query=all --name=sdx | grep ID_SERIAL | sed "s/_/-/g"

Alternatively, use a GUI utility to manage the configuration file, such as gnome-disk-utility.

Troubleshooting

Hidden devices

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
[...]

Broken standby timer

The udisks daemon polls S.M.A.R.T. data from drives regularly. Hard drives with a longer standby timeout than the polling interval may fail to enter standby. Drives that are already spun down are usually not affected. There seems no way to disable polling or change the interval as for udisks2 by now. See [5], [6].

However, Standby timeout applied by udisks2 seems to be unaffected. To set standby timeout via udisks, see #Apply ATA settings.

Other possible workarounds could be setting the timeout below the polling interval (10 minutes) or forcing a manual spindown using hdparm -y /dev/sdx.

NTFS mount failing

If mounting a ntfs partition fails with the error:

Error mounting /dev/sdXY at [...]: wrong fs type, bad option, bad superblock on /dev/sdXY, missing codepage or helper program, or other error

and in the kernel log with journalctl/dmesg ran as root:

ntfs: (device sdXY): parse_options(): Unrecognized mount option windows_names.

Then the problem is that udisks is trying to use the kernel ntfs driver, which does not understand this (default) mount option. For this to work the optional dependency NTFS-3G must be installed.

NTFS file creation failing (filename-dependent)

udisks 2.8.2 introduced a breaking change by adding windows_names to NTFS mount options, preventing creation of Win32-incompatible filenames such as nul, screenshot 23-08-21 19:22.jpg. Among other things, this causes Steam Proton to stop initializing. To revert this behavior, use:

/etc/udisks2/mount_options.conf

[defaults]
ntfs:ntfs_defaults=uid=$UID,gid=$GID

Bad filenames generally do not cause issues in Windows unless accessed. chkdsk will treat these names as errors and move the renamed files to found.nnn folders under filesystem root.