Why is my udev-fired script not working?

I created a udev rule in order to sync my USB drive with my documents folder, but it doesn’t seem to be working.

95-usb-auto-sync.rules:

ACTION=="add", ATTRS{idVendor}=="0930", ATTRS{idProduct}=="1408", RUN+="/home/riccardo/Documents/Scripts/sync-riccardo-usb.sh"

/home/riccardo/Documents/Scripts/sync-riccardo-usb.sh:

#!/bin/bash

rsync -a --delete '/home/riccardo/Documents/Development/' '/run/media/riccardo/Riccardo/Documents/Development' --exclude='*/node_modules' >> /home/riccardo/Documents/Scripts/log.txt
rsync -a --delete '/home/riccardo/Documents/KiCAD/' '/run/media/riccardo/Riccardo/Documents/KiCAD' >> /home/riccardo/Documents/Scripts/log.txt
rsync -a --delete '/home/riccardo/Documents/Personal Files/' '/run/media/riccardo/Riccardo/Documents/Personal Files' >> /home/riccardo/Documents/Scripts/log.txt
rsync -a --delete '/home/riccardo/Documents/Scripts/' '/run/media/riccardo/Riccardo/Documents/Scripts' >> /home/riccardo/Documents/Scripts/log.txt

I added the ‘>> /home/riccardo/Documents/Scripts/log.txt’ part to check if the script was actually executed. The log.txt file remained blank though.

Toshiba USB Drive Udev info:

  looking at device '/devices/pci0000:00/0000:00:14.0/usb4/4-2':
    KERNEL=="4-2"
    SUBSYSTEM=="usb"
    DRIVER=="usb"
    ATTR{authorized}=="1"
    ATTR{avoid_reset_quirk}=="0"
    ATTR{bConfigurationValue}=="1"
    ATTR{bDeviceClass}=="00"
    ATTR{bDeviceProtocol}=="00"
    ATTR{bDeviceSubClass}=="00"
    ATTR{bMaxPacketSize0}=="9"
    ATTR{bMaxPower}=="296mA"
    ATTR{bNumConfigurations}=="1"
    ATTR{bNumInterfaces}==" 1"
    ATTR{bcdDevice}=="0001"
    ATTR{bmAttributes}=="80"
    ATTR{busnum}=="4"
    ATTR{configuration}==""
    ATTR{devnum}=="2"
    ATTR{devpath}=="2"
    ATTR{idProduct}=="1408"
    ATTR{idVendor}=="0930"
    ATTR{ltm_capable}=="no"
    ATTR{manufacturer}=="TOSHIBA"
    ATTR{maxchild}=="0"
    ATTR{product}=="USB FLASH DRIVE"
    ATTR{quirks}=="0x0"
    ATTR{removable}=="removable"
    ATTR{serial}=="C03FD5FBA9CDC1401D7FB227"
    ATTR{speed}=="5000"
    ATTR{urbnum}=="11182"
    ATTR{version}==" 3.00"

Thank you,

Riccardo

Answers:

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Method 1

man udev explains that the RUN+= key should not be used for long running tasks:

This can only be used for very short-running foreground tasks. Running an event process for a long period of time may block all further events
for this or a dependent device.

Starting daemons or other long-running processes is not appropriate for udev; the forked processes, detached or not, will be unconditionally
killed after the event handling has finished.

The correct approach, for modern systems that use systemd, is SYSTEMD_WANTS. From man systemd.device:

THE UDEV DATABASE

The settings of device units may either be configured via unit files, or directly from the udev database (which is recommended). The following udev
device properties are understood by systemd:

SYSTEMD_WANTS=, SYSTEMD_USER_WANTS=
Adds dependencies of type Wants from the device unit to all listed units. The first form is used by the system systemd instance, the second by
user systemd instances. Those settings may be used to activate arbitrary units when a specific device becomes available.

Note that this and the other tags are not taken into account unless the device is tagged with the “systemd” string in the udev database, because
otherwise the device is not exposed as a systemd unit (see above).

So, your udev rule would become:

ACTION=="add", ATTRS{idVendor}=="0930", ATTRS{idProduct}=="1408", SYSTEMD_WANTS="rsync_backup.service"

And you write a service file to call your backup script when the device is mounted:

[Unit]
Description=Backup riccardo's stuff
Requires=media-Riccardo.mount
After=media-Riccardo.mount

[Service]
ExecStart=/usr/local/bin/rsync_backup_thing

[Install]
WantedBy=media-Riccardo.mount

When /media/Riccardo is mounted, your bash script will be triggered.

Method 2

As @jasonwryan suggested I changed the udev rule to:

ACTION=="add", ATTRS{idVendor}=="0930", ATTRS{idProduct}=="1408", ENV{SYSTEMD_WANTS}="usb-auto-sync.service"

with usb-auto-sync.service:

[Unit]
Description=Auto Sync USB

[Service]
ExecStart=/home/riccardo/Documents/Scripts/sync-riccardo-usb.sh
StandardOutput=null

[Install]
WantedBy=multi-user.target
Alias=usbauto-sync.service

I enabled the service and now the script is firing.

All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0