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Command to determine ports of a device (like /dev/ttyUSB0)

Below is a quick and dirty script which walks through devices in /sys looking for USB devices with a ID_SERIAL attribute. Typically only real USB devices will have this attribute, and so we can filter with it. If we don’t, you’ll see a lot of things in the list that aren’t physical devices.

#!/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/"* ]] && exit
        eval "$(udevadm info -q property --export -p $syspath)"
        [[ -z "$ID_SERIAL" ]] && exit
        echo "/dev/$devname - $ID_SERIAL"
    )
done

On my system, this results in the following:

/dev/ttyACM0 - LG_Electronics_Inc._LGE_Android_Phone_VS930_4G-991c470
/dev/sdb - Lexar_USB_Flash_Drive_AA26MYU15PJ5QFCL-0:0
/dev/sdb1 - Lexar_USB_Flash_Drive_AA26MYU15PJ5QFCL-0:0
/dev/input/event5 - Logitech_USB_Receiver
/dev/input/mouse1 - Logitech_USB_Receiver
/dev/input/event2 - Razer_Razer_Diamondback_3G
/dev/input/mouse0 - Razer_Razer_Diamondback_3G
/dev/input/event3 - Logitech_HID_compliant_keyboard
/dev/input/event4 - Logitech_HID_compliant_keyboard

Explanation:

find /sys/bus/usb/devices/usb*/ -name dev

Devices which show up in /dev have a dev file in their /sys directory. So we search for directories matching this criteria.

syspath="${sysdevpath%/dev}"

We want the directory path, so we strip off /dev.

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

This gives us the path in /dev that corresponds to this /sys device.

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

This filters out things which aren’t actual devices. Otherwise you’ll get things like USB controllers & hubs. The exit exits the subshell, which flows to the next iteration of the loop.

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

The udevadm info -q property --export command lists all the device properties in a format that can be parsed by the shell into variables. So we simply call eval on this. This is also the reason why we wrap the code in the parenthesis, so that we use a subshell, and the variables get wiped on each loop.

[[ -z "$ID_SERIAL" ]] && exit

More filtering of things that aren’t actual devices.

echo "/dev/$devname - $ID_SERIAL"

I hope you know what this line does 🙂

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