Automount USB drives with systemd

Solution 1:

After several false starts I figured this out. The key is to add a systemd unit service between udev and a mounting script.

(For the record, I was not able to get this working using udisks2 (via something like udisksctl mount -b /dev/sdb1) called either directly from a udev rule or from a systemd unit file. There seems to be a race condition and the device node isn't quite ready, resulting in Error looking up object for device /dev/sdb1. Unfortunate, since udisks2 could take care of all the mount point messyness...)

The heavy lifting is done by a shell script, which takes care of creating and removing mount points, and mounting and unmounting the drives.

/usr/local/bin/usb-mount.sh

#!/bin/bash

# This script is called from our systemd unit file to mount or unmount
# a USB drive.

usage()
{
    echo "Usage: $0 {add|remove} device_name (e.g. sdb1)"
    exit 1
}

if [[ $# -ne 2 ]]; then
    usage
fi

ACTION=$1
DEVBASE=$2
DEVICE="/dev/${DEVBASE}"

# See if this drive is already mounted, and if so where
MOUNT_POINT=$(/bin/mount | /bin/grep ${DEVICE} | /usr/bin/awk '{ print $3 }')

do_mount()
{
    if [[ -n ${MOUNT_POINT} ]]; then
        echo "Warning: ${DEVICE} is already mounted at ${MOUNT_POINT}"
        exit 1
    fi

    # Get info for this drive: $ID_FS_LABEL, $ID_FS_UUID, and $ID_FS_TYPE
    eval $(/sbin/blkid -o udev ${DEVICE})

    # Figure out a mount point to use
    LABEL=${ID_FS_LABEL}
    if [[ -z "${LABEL}" ]]; then
        LABEL=${DEVBASE}
    elif /bin/grep -q " /media/${LABEL} " /etc/mtab; then
        # Already in use, make a unique one
        LABEL+="-${DEVBASE}"
    fi
    MOUNT_POINT="/media/${LABEL}"

    echo "Mount point: ${MOUNT_POINT}"

    /bin/mkdir -p ${MOUNT_POINT}

    # Global mount options
    OPTS="rw,relatime"

    # File system type specific mount options
    if [[ ${ID_FS_TYPE} == "vfat" ]]; then
        OPTS+=",users,gid=100,umask=000,shortname=mixed,utf8=1,flush"
    fi

    if ! /bin/mount -o ${OPTS} ${DEVICE} ${MOUNT_POINT}; then
        echo "Error mounting ${DEVICE} (status = $?)"
        /bin/rmdir ${MOUNT_POINT}
        exit 1
    fi

    echo "**** Mounted ${DEVICE} at ${MOUNT_POINT} ****"
}

do_unmount()
{
    if [[ -z ${MOUNT_POINT} ]]; then
        echo "Warning: ${DEVICE} is not mounted"
    else
        /bin/umount -l ${DEVICE}
        echo "**** Unmounted ${DEVICE}"
    fi

    # Delete all empty dirs in /media that aren't being used as mount
    # points. This is kind of overkill, but if the drive was unmounted
    # prior to removal we no longer know its mount point, and we don't
    # want to leave it orphaned...
    for f in /media/* ; do
        if [[ -n $(/usr/bin/find "$f" -maxdepth 0 -type d -empty) ]]; then
            if ! /bin/grep -q " $f " /etc/mtab; then
                echo "**** Removing mount point $f"
                /bin/rmdir "$f"
            fi
        fi
    done
}

case "${ACTION}" in
    add)
        do_mount
        ;;
    remove)
        do_unmount
        ;;
    *)
        usage
        ;;
esac

The script, in turn, is called by a systemd unit file. We use the "@" filename syntax so we can pass the device name as an argument.

/etc/systemd/system/[email protected]

[Unit]
Description=Mount USB Drive on %i

[Service]
Type=oneshot
RemainAfterExit=true
ExecStart=/usr/local/bin/usb-mount.sh add %i
ExecStop=/usr/local/bin/usb-mount.sh remove %i

Finally, some udev rules start and stop the systemd unit service on hotplug/unplug:

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

KERNEL=="sd[a-z][0-9]", SUBSYSTEMS=="usb", ACTION=="add", RUN+="/bin/systemctl start usb-mount@%k.service"

KERNEL=="sd[a-z][0-9]", SUBSYSTEMS=="usb", ACTION=="remove", RUN+="/bin/systemctl stop usb-mount@%k.service"

This seems to do the trick! A couple of useful commands for debugging stuff like this:

• udevadm control -l debug turns on verbose logging to /var/log/syslog so you can see what's happening.
• udevadm control --reload-rules after you modify files in the rules.d dir (may not be necessary, but can't hurt...).
• systemctl daemon-reload after you modify systemd unit files.

Solution 2:

there is a new, succinct systemd auto-mount option which can be used with fstab which allows you to use all the standardized mount permission options, and it looks like this:

  x-systemd.automount

an example of it in an fstab line:

  /dev/sdd1   /mnt/hitachi-one     auto     noauto,x-systemd.automount     0 2

the noauto option will mean it will not attempt to be mounted at boot, as with older software autofs.

after adding a new x-systemd.automount line to fstab you then need to run:

  sudo systemctl daemon-reload

and then both, or one, of the following:

  sudo systemctl restart remote-fs.target
  sudo systemctl restart local-fs.target

for more infomation about it:

https://wiki.archlinux.org/index.php/Fstab#Automount_with_systemd

---

Solution 3:

Using pmount, systemd and Mike Blackwell's approach, you can simplify the whole thing:

/etc/systemd/system/[email protected]

[Unit]
Description=Mount USB Drive on %i
[Service]
Type=oneshot
RemainAfterExit=true
ExecStart=/usr/bin/pmount --umask 000 /dev/%i /media/%i
ExecStop=/usr/bin/pumount /dev/%i

/etc/udev/rules.d/99-usb-mount.rules

ACTION=="add",KERNEL=="sd[a-z][0-9]*",SUBSYSTEMS=="usb",RUN+="/bin/systemctl start usb-mount@%k.service"
ACTION=="remove",KERNEL=="sd[a-z][0-9]*",SUBSYSTEMS=="usb",RUN+="/bin/systemctl stop usb-mount@%k.service"

HTH and thank you Mike.

---

Solution 4:

I have modified the script from @MikeBlackwell to:

• recognize device names that span multiple characters, not just /dev/sd[a-z] but /dev/sd[a-z]*; often the case with servers that have larger number of spindles.
• track the list of automounted drives at /var/log/usb-mount.track
• log the actions to /var/log/messages with tag usb-mount.sh
• prefix device name with the device label for the mount point to not run in to problems with drives that haven't been assigned a label(empty?):/media/sdd2_usbtest, /media/sdd2_
• included wrapper scripts to place the files appropriately and undo if required

Since @MikeBlackwell has already done most of the heavy lifting, I chose not to rewrite it; just made the necessary changes. I have acknowledged his work sighting his name and URI of the original answer.

Find it at https://github.com/raamsri/automount-usb

---

Solution 5:

I'd go with Warren Young's answer I have a few changes I made to

I added some space protection as it was giving errors from the eval of the environment for the drive.

I added a section to chmod a usb disk so all users have full access to non ntfs or vfat disks.

/usr/local/bin/usb-mount.sh

#!/bin/bash

# This script is called from our systemd unit file to mount or unmount
# a USB drive.

usage()
{
    echo "Usage: $0 {add|remove} device_name (e.g. sdb1)"
    exit 1
}

if [[ $# -ne 2 ]]; then
    usage
fi

ACTION="$1"
DEVBASE="$2"
DEVICE="/dev/${DEVBASE}"

# See if this drive is already mounted, and if so where
MOUNT_POINT=$(/bin/mount | /bin/grep ${DEVICE} | /usr/bin/awk '{ print $3 }')

do_mount()
{
    if [[ -n "${MOUNT_POINT}" ]]; then
        echo "Warning: ${DEVICE} is already mounted at ${MOUNT_POINT}"
        exit 1
    fi

    # Get info for this drive: $ID_FS_LABEL, $ID_FS_UUID, and $ID_FS_TYPE
    # added some sed's to avoid space issues
    eval $(/sbin/blkid -o udev ${DEVICE}|sed 's/=/="/'|sed 's/$/"/')

    # Figure out a mount point to use
    LABEL="${ID_FS_LABEL}"
    if [[ -z "${LABEL}" ]]; then
        LABEL="${DEVBASE}"
    elif /bin/grep -q " /media/${LABEL} " /etc/mtab; then
        # Already in use, make a unique one
        LABEL+="-${DEVBASE}"
    fi
    MOUNT_POINT="/media/${LABEL}"

    echo "Mount point: ${MOUNT_POINT}"

    /bin/mkdir -p "${MOUNT_POINT}"

    # Global mount options
    OPTS="rw,relatime"
    #added a chmod checker for file systems that don't 
    #understand allow all to read write
    CHMOD=no
    # File system type specific mount options
    if [[ ${ID_FS_TYPE} == "vfat" ]]; then
        OPTS+=",users,gid=100,umask=000,shortname=mixed,utf8=1,flush"
    #added options I wanted on ntfs
    elif [[ ${ID_FS_TYPE} == "ntfs" ]]; then
        OPTS+=",user,users,umask=000,allow_other"
    else
       CHMOD=yes
    fi

    if ! /bin/mount -o "${OPTS}" ${DEVICE} "${MOUNT_POINT}"; then
        echo "Error mounting ${DEVICE} (status = $?)"
        /bin/rmdir "${MOUNT_POINT}"
        exit 1
    fi


    echo "**** Mounted ${DEVICE} at ${MOUNT_POINT} ****"
    if [ "${CHMOD}" = "yes" ];then
        /usr/bin/find "${MOUNT_POINT}" -type f -exec chmod 0666 {} \;
        /usr/bin/find "${MOUNT_POINT}" -type d -exec chmod 0777 {} \;
    fi
}

do_unmount()
{
    if [[ -z ${MOUNT_POINT} ]]; then
        echo "Warning: ${DEVICE} is not mounted"
    else
        /bin/umount -l ${DEVICE}
        echo "**** Unmounted ${DEVICE}"
    fi

    # Delete all empty dirs in /media that aren't being used as mount
    # points. This is kind of overkill, but if the drive was unmounted
    # prior to removal we no longer know its mount point, and we don't
    # want to leave it orphaned...
    for f in /media/* ; do
        if [[ -n $(/usr/bin/find "$f" -maxdepth 0 -type d -empty) ]]; then
            if ! /bin/grep -q " $f " /etc/mtab; then
                echo "**** Removing mount point $f"
                /bin/rmdir "$f"
            fi
        fi
    done
}

case "${ACTION}" in
    add)
        do_mount
        ;;
    remove)
        do_unmount
        ;;
    *)
        usage
        ;;
 esac