Serial Thrillers: Bash Script for USB Identification

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If you need to identify USB devices connected to your Linux system, it can be a tedious process involving multiple commands and parsing all the lengthy outputs.

Automation can simplify this task significantly.

In this post, we’ll walk through a Bash script designed to list all USB devices connected to your system along with their serial numbers.

The Script

Here’s the script in question:

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#!/bin/bash

for sysdevpath in $(find /sys/bus/usb/devices/usb*/ -name dev); do
    (
        syspath="${sysdevpath%/dev}"
        devname="$(udevadm info -q name -p $syspath)"
        [[ "$devname" == "bus/"* ]]
        eval "$(udevadm info -q property --export -p $syspath)"
        [[ -z "$ID_SERIAL" ]]
        echo "/dev/$devname - $ID_SERIAL"
    )
done

Understanding the Script

Let’s break down what this script does step by step:

  1. Finding USB Devices: The script starts by finding all device paths under /sys/bus/usb/devices/usb*/ that end with dev. This path contains directories and files representing USB devices and their attributes.

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    for sysdevpath in $(find /sys/bus/usb/devices/usb*/ -name dev); do

  2. Extracting the Syspath: For each device path found, it extracts the parent directory path (syspath) by removing the trailing /dev part.

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    syspath="${sysdevpath%/dev}"

  3. Getting the Device Name: The script uses udevadm info to query the device name corresponding to the syspath. This command provides details about the device.

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    devname="$(udevadm info -q name -p $syspath)"

  4. Filtering Out Non-USB Devices: The script checks if the device name starts with “bus/“ and skips such devices since they’re not actual USB devices.

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    [[ "$devname" == "bus/"* ]]

  5. Exporting Device Properties: It then uses udevadm info again to export all properties of the device into the current shell environment. This makes properties like ID_SERIAL available as shell variables.

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    eval "$(udevadm info -q property --export -p $syspath)"

  6. Checking Serial Number: The script verifies if ID_SERIAL is set. If it’s not, it continues to the next iteration. This ensures only devices with a serial number are considered.

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    [[ -z "$ID_SERIAL" ]]

  7. Outputting the Device Information: Finally, the script prints the device’s path (/dev/$devname) along with its serial number ($ID_SERIAL).

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    echo "/dev/$devname - $ID_SERIAL"

Running the Script

To use this script, save it to a file, for example list_usb_devices.sh, and give it execute permissions:

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chmod +x list_usb_devices.sh

Run the script with:

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./list_usb_devices.sh

This will output a list of all connected USB devices and their serial numbers, like this:

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/dev/sda1 - 1234567890
/dev/sdb1 - 0987654321

Conclusion

This Bash script offers an approach to identify USB devices and their serial numbers on a Linux system. It’s based on udevadm to gather information about each device. By automating this process, you can save time and reduce the complexity involved in managing USB devices.

Feel free to adapt and expand this script based on your specific requirements. Happy scripting!