43

I have a question regarding the ports in Linux. If I connect my device via USB and want to check its port I can't do it using the command lsusb, which only specifies bus number and device number on this bus:

[ziga@Ziga-PC ~]$ lsusb
Bus 003 Device 007: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC

Is there a command that tells me the port the device is connected to directly? Only way to do this until now was to disconect and reconnect and using the command:

[ziga@Ziga-PC ~]$ dmesg | grep tty
[    0.000000] console [tty0] enabled
[    0.929510] 00:09: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A
[    4.378109] systemd[1]: Starting system-getty.slice.
[    4.378543] systemd[1]: Created slice system-getty.slice.
[    8.786474] usb 3-4.4: FTDI USB Serial Device converter now attached to ttyUSB0

In the last line it can be seen that my device is connected to /dev/ttyUSB0.

  • What are you trying to accomplish? Do you want to associate a device in /dev with an entry in lsusb? Or do you want to list all devices in /dev that are derived from a physical USB device? Or are you just wanting ls /dev/ttyUSB*? – Patrick Jul 11 '14 at 17:00
  • I just need a command which will give me port of a device and will not push me to disconnect and reconnect my devices. ls /dev/ttyUSB* will only list maybee 10 ports but from this list I cannot tell which one is for my device. – 71GA Jul 15 '14 at 16:41
  • I found this to be helpful. lsusb -v – tjaart55 Mar 27 at 7:56
76

I'm not quite certain what you're asking. You mention 'port' several times, but then in your example, you say the answer is /dev/ttyUSB0, which is a device dev path, not a port. So this answer is about finding the dev path for each device.

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/"* ]] && continue
        eval "$(udevadm info -q property --export -p $syspath)"
        [[ -z "$ID_SERIAL" ]] && continue
        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/"* ]] && continue

This filters out things which aren't actual devices. Otherwise you'll get things like USB controllers & hubs.
 

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" ]] && continue

More filtering of things that aren't actual devices.
 

echo "/dev/$devname - $ID_SERIAL"

I hope you know what this line does :-)

  • 2
    Thank you. I will learn a lot from your anwser and now I see that terms werent completely clear to me. Is there any shorter way? Maybee a command already integrated in the Linux itself? – 71GA Jul 17 '14 at 8:43
  • Nope. If there was a pre-existing command, I would happily recommend it. – Patrick Jul 17 '14 at 17:07
  • Suggest to change /bin/bash to /bin/sh and remove the ( ) for max compatibility – albfan Feb 5 at 14:46
10

You can use this command to explore your device if connected to usb0:

udevadm info -a -p  $(udevadm info -q path -n /dev/ttyUSB0)
  • The top answer didn't work on my machine, but this worked great. Thanks! – johnny_boy Jun 19 '17 at 14:45
2

You could try something like this below.

echo -n "/dev/"; dmesg | grep tty|grep USB|rev|awk '{print $1}'|rev
  • ow my eyes! dmesg | awk '/tty/ && /USB/ {print "/dev/"$1}' (The equivalent but clean...but still strange code; why not just ttyUSB together? and what was 2x rev for?) – Peter Nov 13 '17 at 11:40
  • 1
    The rev is used so the last field is accessed, this can be replaced by $NF: giving dmesg | awk '/tty/ && /USB/ {print "/dev/"$NF}' – Léo Germond Apr 19 at 13:47
2

Perhaps you would like to know just the path to USB-serial adapter that connected last?

dmesg | awk '/tty/ && /USB/ {print "/dev/"$10}'|tail -1
1

Assuming that you know what the device you plugged in is, in 14.04 Ubuntu, at least, there is the command usb-devices that you can look through and find the information:

$ usb-devices

T:  Bus=01 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#=  1 Spd=480 MxCh= 3
D:  Ver= 2.00 Cls=09(hub  ) Sub=00 Prot=00 MxPS=64 #Cfgs=  1
P:  Vendor=1d6b ProdID=0002 Rev=04.04
S:  Manufacturer=Linux 4.4.0-131-generic ehci_hcd
S:  Product=EHCI Host Controller
S:  SerialNumber=0000:00:1a.0
C:  #Ifs= 1 Cfg#= 1 Atr=e0 MxPwr=0mA
I:  If#= 0 Alt= 0 #EPs= 1 Cls=09(hub  ) Sub=00 Prot=00 Driver=hub

And the first line lists bus and port, as well as the device number that lsusb gives.

protected by Community Apr 28 at 4:13

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