Description:

udevmonitor 1.3.0

udev_monitor
Monitor linux udev events and execute actions on detection
Designed to execute actions when USB devices are plugged-in / removed




udev_monitor works with Linux udev and monitors it's events.
Upon a specific event for a given device (in VENDOR_ID:PRODUCT_ID format), it will execute an action.
udev_monitor has been used to:

Re-attach USB devices to virtual machines after they're unplugged - plugged in again
Run a full USB reset when device is plugged in (fixes some of the USB UPS that identify as Cypress Semiconductor USB to Serial)

Setup
pip install udev_monitor

Quickstart example
This is a realworld example to detect most USB UPS and execute a script upon plug-in.
Run script /usr/local/bin/restart_nut_driver.sh with argument 0665:5161 everytime USB device with vendor id 0665 and product id 5161 is added or removed
udev_monitor --devices 0665:5161 --udev-actions add,remove --filters=usb --action /usr/local/bin/restart_nut_driver.sh

Full usage
--devices List of comma separated devices to monitor. Example:
'0665:5161, 8086:1234'
If no devices are given, all devices are monitored.
--udev-actions List of udev events which should trigger and action
Valid actions are: 'add', 'remove', 'change', 'online', 'offline'. Defaults to 'add, change, online'
--filters List of comma separated udev monitor filters. Filters are applied with OR logic. Example:
'usb,tty'
--action Path to script. Script will get detected device as only argument.
--timeout Maximum execution time for script
--config Optional path to config file

Optional configuration file layout
[UDEV_MONITOR]
devices = '0665:5161'
filters = 'usb'
action = '/path/to/script.sh'
udev_events = 'add'
timeout = 3600

Setting monitor up as a service

copy file scripts/udev_monitor@.service to /etc/systemd/system
Reload daemons
Create configuration file in /etc/udev_monitor from example config in scripts/udev_monitor.conf.example
Launch service

Example:
cp scripts/udev_monitor\@.service to /etc/systemd/system
systemctl daemon-reload

mkdir /etc/udev_monitor
cat << EOF > /etc/udev_monitor/udev_monitor1.conf
devices = '0665:5161'
filters = 'usb'
action = '/path/to/script.sh'
udev_events = 'add'
timeout = 3600
EOF

systemctl enable --now udev_monitor@udev_monitor1.conf

You can launch multiple udev_monitor instances by creating multiple conf files and loading them with:
systemctl enable --now udev_monitor@umy_ups.conf
systemctl enable --now udev_monitor@my_modem.conf
systemctl enable --now udev_monitor@my_harddrive.conf

Further examples
Automatically attach an USB device (4G modem) to a KVM virtual machine with libvirt and udev_monitor
Let's imagine we have a Sierra 4G model that identifies as 1199:9097, and we would like to attach it to VM modem.vm.local
Grab yourself a copy of usb_reset via pip install usb_reset
Create the following script as /usr/local/bin/attach_modem.sh and make it executable with chmod +x /usr/local/bin/attach_modem.sh
#!/usr/bin/env bash

# /usr/local/bin/usb_reset.py --reset-device --device 1199:9071

virsh detach-device sms.badmin.local /root/4G_modem.xml
virsh attach-device sms.badmin.local /root/4G_modem.xml

Create the file /root/4G_modem.xml containing:
<hostdev mode='subsystem' type='usb' managed='yes'>
<source>
<vendor id='0x1199'/>
<product id='0x9071'/>
</source>
</hostdev>

Now we must execute that script everytime the USB 4G modem is plugged-in, so we get to re-attach it to the VM.
In order to do so, let's create the following conf file in /etc/udev_monitor/modem.conf
[UDEV_MONITOR]
devices = 1199:9071
filters = usb
action = /usr/local/bin/attach_modem.sh
udev_events = add
timeout = 300

Now let's create a systemd service by copying udev_monitor@.service from this git repo to /etc/systemd/system
Once this is done, we just can activate the service with systemctl enable --now udev_monitor@modem.conf
Reset a lawless UPS USB
Some of the USB uninterrupted power supplies (smaller devices) have a quite unreliable USB/Serial interface.
Sometimes it's needed to restart the usb port for the device to work properly.
In that case, we can use udev_monitor to trigger a usb reset on device plug-in.

License

For personal and professional use. You cannot resell or redistribute these repositories in their original state.

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