How to Test USB Port in Linux

Testing USB ports in Linux can be performed by checking the system logs, monitoring the port’s power output, and using commands to list USB devices and detect hardware issues. Here are the steps to perform a comprehensive USB port test:

Step 1: Physical Inspection

1. Check the USB Connection:
   • Ensure that the USB device is properly connected to the USB port. Sometimes, a physical inspection can reveal issues such as debris blocking the port or a loose connection.

Step 2: Monitor USB Device Insertion

1. Watch Kernel Messages:
   • Open a terminal and run dmesg -w to monitor kernel messages in real-time.
   • Insert a USB device into the port you want to test. You should see messages that indicate a new USB device has been detected. If you don’t see any new messages upon inserting a USB device, there may be an issue with the port.

Step 3: List USB Devices

1. Use lsusb:
   • In the terminal, type lsusb to list all USB devices connected to your system. This will show you the USB devices that the system currently recognizes.

Step 4: Check USB Device Specific Information

1. Detailed Device Information:
   • Run lsusb -v to get verbose output, including the power each device is requesting. This information can be helpful if you suspect a device is drawing too much power or not receiving enough.

Step 5: Check USB Device Filesystem (For Storage Devices)

1. Mount the Device:
   • If you’re testing a USB storage device, try to mount it manually if it does not mount automatically. You can use the mount command, for example:
     mount /dev/sdx1 /mnt

   • Replace /dev/sdx1 with the appropriate device identifier for your USB storage device.

Step 6: Use udevadm for Event Monitoring

1. Monitor Events:
   • Run udevadm monitor to see events related to all device activity, which includes USB insertions and removals. When you plug in or remove a USB device, udevadm should display information about that event.

Step 7: Test USB Port Output Power

1. Measure Power Output:
   • For advanced USB testing, you can use a USB multimeter or USB power meter to measure the actual power output of the USB port.

Step 8: Check Hardware Connections

1. Internal Connections:
   • On a desktop PC, if a USB port isn’t working, check to make sure that the internal cable connecting the port to the motherboard is secure.

Step 9: Analyze System Logs

1. Review System Logs:
   • Look into /var/log/syslog for any messages that might relate to USB issues. You can use grep to filter for USB-related messages:
     grep -i usb /var/log/syslog


Step 10: Testing USB Port with a Known Good Device

1. Test with Different Devices:
   • If a particular USB device isn’t recognized, test the port with a device that you know is working properly.

Step 11: Testing All Ports

1. Repeat Tests:
   • Repeat these tests with all USB ports on your system to determine if the issue is with a single port or a system-wide problem.

Troubleshooting Tips:

• If a USB port isn’t working, try rebooting the system. Sometimes a simple reboot can resolve a temporary hardware glitch.
• Check BIOS/UEFI settings to ensure USB ports are enabled.
• Look for updates to your Linux kernel or system firmware.
• If the port physically appears to be damaged, it may need to be repaired or replaced, especially if it is a laptop or a sealed system.

By following these steps, you should be able to determine whether your Linux system’s USB ports are functioning correctly or identify issues that need to be addressed.