Terrarium's questions

I am trying to access my webcam through OpenCV in WSL2 (Ubuntu). I found this blog post where it explains how to connect USB devices to WSL2. Running usbipd wsl list in windows command prompt lists the following devices:

> usbipd wsl list
BUSID  VID:PID    DEVICE                                                        STATE
1-1    0c45:6725  Integrated Webcam                                             Not attached
1-2    046d:c534  USB Input Device                                              Not attached
1-3    0cf3:e007  Qualcomm QCA61x4A Bluetooth                                   Not attached
1-4    27c6:639c  Goodix Moc Fingerprint                                        Not attached
2-2    8564:7000  USB Mass Storage Device                                       Not attached

Here my machine's integrated webcam is a USB device with BUSID 1-1. I ran usbipd wsl attach --busid 1-1 to connect my integrated webcam to WSL.

Now from WSL, typing lsusb lists the devices as follows:

> lsusb
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 003: ID 0c45:6725 Microdia Integrated_Webcam_HD
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

It looks like the integrated webcam has been successfully connected to WSL (listed as Microdia Integrated_Webcam_HD).

This is the code used to access the webcam:

import cv2
import sys

source = cv2.VideoCapture(0)

win_name = 'Camera Preview'
cv2.namedWindow(win_name, cv2.WINDOW_NORMAL)

while cv2.waitKey(1) != 27:  # Escape
    has_frame, frame = source.read()
    if not has_frame:
        break
    cv2.imshow(win_name, frame)

source.release()
cv2.destroyWindow(win_name)

Here cv2.VideoCapture() takes an index as argument. The OpenCV documentation mentions:

If I run the code above with 0 as the argument, I get the following output:

[ WARN:[email protected]] global /io/opencv/modules/videoio/src/cap_v4l.cpp (889) open VIDEOIO(V4L2:/dev/video0): can't open camera by index

I have connected USB devices to WSL, but still I am not able to access the integrated webcam. Any ideas how to get around this problem would be much appreciated!

Exercise 2 from Missing Semester asks the following:

Run PATH= and try running the previous commands again, some work and some don’t, can you figure out why?

Setting PATH= removes all the contents from the PATH variable. Then echo $PATH yields just an empty line. But when I restart the shell, all the contents of the PATH variable are there again. My question is where does PATH variable get its values from when I restart the shell?

If I do this:

touch {1,2,3}.txt

I get

1.txt 2.txt 3.txt

But if I do this

touch {"File 1", "File 2"}.txt

I don't get expected 'File 1.txt' 'File 2.txt'. What is the proper approach in this case?

I was following a tutorial from "The Missing Semester" here (timestamp included in link). There was supposed to be an led directory in /sys/class. I am using WSL2 and I could not find any such directory. Does WSL hide some of the /sys/class locations? And is there any way accessing those without having to dual boot my machine?

I am using Ubuntu 20.04 on my Asus ROG GL503GE (Nvidia drivers, dual boot). I have added @reboot root echo 60 > /sys/class/power_supply/BAT1/charge_control_end_threshold on /etc/crontab, but still when I reboot my computer, the command does not run. I need to run this to limit my battery charging to 60% and had that command ran successfully, my charging LED would have turned from orange to white. Now I have to manually edit the file every time I reboot my computer. Any solutions how to get this running?

A while ago I installed Ubuntu on my Windows machine (Asus ROG GL503GE), which has an Nvidia GPU. In order for that GPU to work when booting into Ubuntu, I have to manually disable secure boot every time. Otherwise all my GPU heavy apps would struggle to run using integrated Intel GPU. How do I enable Nvidia GPU in Ubuntu without having to disable secure boot every time when booting?

I have an Asus ROG GL503 laptop, which came pre-installed with Asus Battery Health Charging software. This software gives me the option to limit my battery charging level to 60% to prolong the overall battery lifespan. Whenever I boot using Ubuntu(18.04), my battery keeps charging until it reaches 100%. Is there any method by which I can limit my battery charging up to a certain level?

My laptop has a GTX graphics card, which had driver related issues while installing Ubuntu (alongside Windows). I had to use the parameter nouveau.modeset=0 while booting Ubuntu for the first time, and then install the drivers required for my graphics card.

At first, I was having trouble installing those drivers, but after disabling secure boot, everything went on fine.Things were going good until I re-enabled the secure boot from UEFI. After that, Ubuntu booted up fine but it was not able to detect the drivers. (nvidia-smi could not communicate with Nvidia drivers). If I booted Ubuntu with secure boot disabled, no problem occurred.

How can I enable secure boot and have my Nvidia drivers working on Ubuntu at the same time?