Tag: ubuntu

Reset USB Devices on RaspberryPi Ubuntu

Hey everyone,

I ran into a small issue today on my RaspberryPi. Occasionally, when restarting scripts that utilised usb devices (lidar, arduino) the usb connections were locking up. This meant that when I tried to restart the scripts I wasn’t able to reconnect.

My initial solution was to simply restart the Pi each time it occurred. Unfortunately, this became pretty tedious when testing required a lot of relaunching.

In order to get around having to restart each time I used usbreset in a small script attached to my launch files. This allowed me to ensure that all usb devices were ready to go.

for id in $(lsusb | grep -oP 'ID \S+' | awk '{print $2}'); do
    echo "Resetting device $id"
    sudo usbreset "$id"
    sleep 1  # Add a small delay between resets
done

Note that you can also simply paste this into your shell. This was done on a RaspberryPi that has been imaged with Ubuntu, but I expect it will work on Raspbian as well.

Automatically Shutdown a RaspberryPi when the Network is not Reachable

Hi everyone,

I’ve had a bit of an issue recently with my RaspberryPi disconnecting when I’m flooding the network with camera images. Unfortunately I’m using a dodgy TP-Link WiFi range extender and it doesn’t handle the load well at all.

The issue with this is that it means I cannot connect to the RaspberryPi to safely shut it down. I can switch off the power but this risks corrupting the SD card. In order to get around this I added a script to automatically shutdown when the Pi cannot reach my server for 30 seconds (with help from Co-Pilot!).

target_ip="192.168.0.1"  # Replace with your target IP address
ping_timeout=30           # Timeout in seconds
while true; do
    if ping -c 1 -W $ping_timeout $target_ip >/dev/null; then
        echo "Target IP is reachable."
    else
        echo "Target IP is not reachable. Initiating shutdown..."
        sudo shutdown -h now  # Change to "poweroff" if "shutdown" is not available
    fi
    sleep 1
done

To use the script:

  • 1. Open a text editor and paste the script into a new file.
  • 2. Replace the target_ip variable with the IP address you want to monitor.
  • 3. Save the file with a .sh extension (e.g., shutdown_script.sh).
  • 4. Open a terminal and navigate to the directory where you saved the script.
  • 5. Make the script executable by running the following command: chmod +x shutdown_script.sh.
  • 6. Run the script using the following command: ./shutdown_script.sh.

The script will continuously ping the target IP address every second. If the target IP becomes unreachable for 30 seconds, it will shutdown the pi. You might need to run the script with root privileges (sudo) to execute the shutdown command successfully.

To test it I pointed the script at a VM on my main computer and then paused the VM.

chris@robot1:~/robot_ws/src/my_bot$ sudo ./auto_shutdown.sh
[sudo] password for chris: 
Target IP is reachable.
...
Target IP is reachable.
Target IP is reachable.
Target IP is not reachable. Initiating shutdown...

I then tried pinging the Pi from my main computer to confirm it had shutdown:

Chris@Chriss-Mini-8 Journal % ping 192.168.0.123
PING 192.168.0.123 (192.168.0.123): 56 data bytes
ping: sendto: Host is down
ping: sendto: Host is down

RaspberryPi Camera not detected – Ubuntu 20.04.5 LTS

Hi everyone,

I ran into a bit of an issue with a RaspberryPi 4 running Ubuntu 20.04.5 this morning. Running vcgencmd get_camera should have returned supported=1 detected=1 but instead I was getting supported=0 detected=0.

This was a bit of a hard one to track down with Google but I eventually came across a stackoverflow post suggesting the following:

  • Run sudo nano /boot/firmware/config.txt
  • Add start_x=1 at the end
  • Reboot

Check out this post for more info: https://askubuntu.com/a/1244259/770194.

If you’re using a new camera you may also run into this error:

mmal: Cannot read camera info, keeping the defaults for OV5647
mmal: mmal_vc_component_create: failed to create component 'vc.ril.camera' (1:ENOMEM)
mmal: mmal_component_create_core: could not create component 'vc.ril.camera' (1)
mmal: Failed to create camera component
mmal: main: Failed to create camera component
mmal: Only 76M of gpu_mem is configured. Try running "sudo raspi-config" and ensure that "memory_split" has a value of 128 or greater

The fix for this one is to simply append another line to /boot/firmware/config.txt. All you’ll need is gpu_mem=128.

Another issue you might run into is VHCI initialization failed. Generally, that just means you need to add your current user to the video group.

# Check your current user's groups.
groups

# Add your user to the video group.
sudo usermod -aG video <username>

Once you’ve added the group, rebooting should be enough to get past that error.

libgl error pic id driver null – ros2 turtlesim

Hi everyone,

I’m currently following the ros2 turtlesim tutorial with Ubuntu on an M1 Mac with Parallels and Ubuntu. Unfortunately, I hit a ‘device not found’ when trying to start the control node.

A bit of Googling revealed that 3D acceleration might not be enabled. To fix this, all you need to do is the following:

  • Open settings in Parallels (the cog icon)
  • Click the Hardware tab up the top
  • Click Graphics on the left hand side
  • Click Advanced
  • Tick Enable 3D Acceleration

You’ll need to restart the VM, but once that’s done the libgl error should be resolved!

If this doesn’t work, there are a few other things you can check. First, double check that you’ve installed (or re-installed) Parallels Tools.

I have also found that the 3D Acceleration seems to randomly break or reset itself. If it hasn’t automatically unchecked itself, I’ve occasionally had to do the following to get it working again:

  • Stop the VM
  • Disable 3D Acceleration
  • Start the VM
  • Stop the VM
  • Enable 3D Acceleration
  • Start the VM

Another options mentioned in this thread is to set the following environment variable before starting rviz or gazebo: 

export LIBGL_ALWAYS_SOFTWARE=1

The Repository is not Signed – Ubuntu ros2 installation

Hi everyone,

I’m currently installing ros2 on Ubuntu (with Parallels) and ran into the following error:

Hit:1 http://au.ports.ubuntu.com/ubuntu-ports jammy InRelease
Hit:2 http://ports.ubuntu.com/ubuntu-ports jammy-security InRelease
Get:3 http://packages.ros.org/ros2/ubuntu jammy InRelease [4,673 B]
Hit:4 http://au.ports.ubuntu.com/ubuntu-ports jammy-updates InRelease
Err:3 http://packages.ros.org/ros2/ubuntu jammy InRelease
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY F42ED6FBAB17C654
Get:5 http://ports.ubuntu.com/ubuntu-ports jammy-proposed InRelease [270 kB]
Hit:6 http://au.ports.ubuntu.com/ubuntu-ports jammy-backports InRelease
Reading package lists… Done
W: GPG error: http://packages.ros.org/ros2/ubuntu jammy InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY F42ED6FBAB17C654
E: The repository 'http://packages.ros.org/ros2/ubuntu jammy InRelease' is not signed.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.

I was following the official tutorial so I was little surprised to see this crop up. What I hadn’t realised was that I’d missed an error in the output dump while running sudo apt update:

chris@chris-parallels-ubuntu:~$ sudo apt update && sudo apt install curl gnupg lsb-release
sudo curl -sSL https://raw.githubusercontent.com/ros/rosdistro/master/ros.key -o /usr/share/keyrings/ros-archive-keyring.gpg
Hit:1 http://au.ports.ubuntu.com/ubuntu-ports jammy InRelease
Hit:2 http://ports.ubuntu.com/ubuntu-ports jammy-security InRelease
Get:3 http://packages.ros.org/ros2/ubuntu jammy InRelease [4,673 B]
Err:3 http://packages.ros.org/ros2/ubuntu jammy InRelease
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY F42ED6FBAB17C654
Hit:4 http://au.ports.ubuntu.com/ubuntu-ports jammy-updates InRelease
Hit:5 http://ports.ubuntu.com/ubuntu-ports jammy-proposed InRelease
Hit:6 http://au.ports.ubuntu.com/ubuntu-ports jammy-backports InRelease
Reading package lists… Done
W: GPG error: http://packages.ros.org/ros2/ubuntu jammy InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY F42ED6FBAB17C654
E: The repository 'http://packages.ros.org/ros2/ubuntu jammy InRelease' is not signed.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.
sudo: curl: command not found

This was a clean install of Ubuntu and I hadn’t yet installed curl. Luckily, this is a simple fix:

sudo apt update
sudo apt install curl

The current operating system is not capable of running this task. That typically means the task was written for Windows only. For example, written for Windows Desktop PowerShell. – AzureFileCopy@4

Hi everyone,

I am currently setting up an azure pipeline to deploy a ReactApp to a Blob storage container. I was a bit surprised when I hit the following error with an Ubuntu pool:

Task         : Azure file copy
Description  : Copy files to Azure Blob Storage or virtual machines
Version      : 4.184.1
Author       : Microsoft Corporation
Help         : https://docs.microsoft.com/azure/devops/pipelines/tasks/deploy/azure-file-copy
==============================================================================
##[error]The current operating system is not capable of running this task. That typically means the task was written for Windows only. For example, written for Windows Desktop PowerShell.
##[debug]System.InvalidOperationException: The current operating system is not capable of running this task. That typically means the task was written for Windows only. For example, written for Windows Desktop PowerShell.
   at Microsoft.VisualStudio.Services.Agent.Worker.TaskRunner.RunAsync()
   at Microsoft.VisualStudio.Services.Agent.Worker.StepsRunner.RunStepAsync(IStep step, CancellationToken jobCancellationToken)

I did a quick search in the task lists and couldn’t find anything specifically for Linux. A bit of Googling brought up an open Github thread stating that there currently isn’t a built in task to address this issue.

The next best alternative is to use the AzureCli task and invoke it that way:

- task: AzureCLI@1
    displayName: Deploy the UI
    inputs:
      azureSubscription: $(azureSubscription)
      scriptLocation: inlineScript
      inlineScript: |
        az storage blob upload-batch \
          --destination \$web \
          --account-name "$(storageAccountName)" \
          --source "$(Agent.BuildDirectory)/$(outputDir)"

I’ve linked the GitHub issue below. It has a few alternatives to this task as well so worth reading if you’re having issues: https://github.com/microsoft/azure-pipelines-tasks/issues/8920#issuecomment-640596461

Setup MongoDB on an Azure VM

Hi everyone,

I’m currently using a small linux vm to host a MongoDB instance on Azure. These are the steps I followed:

## MongoDB

### Install
https://docs.mongodb.com/manual/tutorial/install-mongodb-on-ubuntu/

1. Import the public key: `wget -qO - https://www.mongodb.org/static/pgp/server-4.4.asc | sudo apt-key add -`
2. Create a list file:  `echo "deb [ arch=amd64,arm64 ] https://repo.mongodb.org/apt/ubuntu bionic/mongodb-org/4.4 multiverse" | sudo tee /etc/apt/sources.list.d/mongodb-org-4.4.list`
   - This is for Ubuntu 18.04, check version using `lsb_release -a` 
3. Reload the local package database: `sudo apt-get update`
4. Install MongoDb: `sudo apt-get install -y mongodb-org`
5. Pin the version to prevent automatic upgrades 
```
echo "mongodb-org hold" | sudo dpkg --set-selections
echo "mongodb-org-server hold" | sudo dpkg --set-selections
echo "mongodb-org-shell hold" | sudo dpkg --set-selections
echo "mongodb-org-mongos hold" | sudo dpkg --set-selections
echo "mongodb-org-tools hold" | sudo dpkg --set-selections
```

### Allow remote access
https://www.digitalocean.com/community/tutorials/how-to-configure-remote-access-for-mongodb-on-ubuntu-20-04

1. sudo nano /etc/mongod.conf
2. Find the `network interfaces` section
3. Find the `bindIp` value
4. Append the public ip of your vm to this address list `bindIp: 0.0.0.0`
   - *Note that this is the VM ip not the ip of the machine you plan to connect from.*
5. Restart MongoDB `sudo systemctl restart mongod`

### Add authentication
1. Connect to the instance from an ssh connection: `mongo --port 27017'
2. Create the user:
https://stackoverflow.com/a/38921949/522859
```
db.createUser(
  {
    user: "YOUR_USERNAME",
    pwd: "YOUR_PASSWORD",
    roles: [ { role: "root", db: "admin" } ]
  }
)
```
3. Restart with access control: `mongod --auth --port 27017 --dbpath /data/db1`
4. Authenticate as the user adminstrator: `mongo --port 27017 -u "YOUR_USERNAME" -p "YOUR_PASSWORD"  --authenticationDatabase "admin"`
5. Locate the commented out security heading and uncomment it.
6. Add `authorized: enabled`
```
security:
  authorization: enabled
```
7. Restart with access control: `mongod --auth --port 27017 --dbpath /data/db1`

Simple Staging/Test Environment with Heroku – Ruby on Rails

Hey everyone,

This is just a quick guide on how to create a test/staging environment with Heroku.

-- Create staging environment
heroku create --remote staging

-- Push to staging app
heroku push staging master

-- Run rake db:migrate on staging app
heroku run rake db:migrate --remote staging

-- Add pgbackups add ons
heroku addons:add pgbackups --remote staging
heroku addons:add pgbackups --remote heroku

-- Create backup of production data
heroku pgbackups:capture --remote heroku

-- Copy to staging environemnt
heroku pgbackups:restore DATABASE `heroku pgbackups:url --remote heroku` --remote staging

-- Create a new config file called staging.rb (/config/environments/staging.rb)

-- Add environment variables
heroku config:add RACK_EVN=staging RAILS_ENV=staging --remote staging

-- Ready to go !

For those of you using git branches etc, the following may come in handy as well:

-- Create local development branch
git branch development

-- Switch to dev branch
git checkout development

-- Make your changes and commit them
git init
git add .
git commit -m "My changes"

-- Push to staging environment (local development branch to staging environment master branch)
git push staging development:master

If you run into any trouble, I found the following links pretty helpful:

http://stackoverflow.com/a/6931462/522859
https://devcenter.heroku.com/articles/pgbackups#transfer
https://devcenter.heroku.com/articles/multiple-environments

Let me know if you’ve got anything to add.

Assets:Precompile (Rake Aborted) – Heroku

Hey everyone,

I ran into the following error over the weekend while trying to push to heroku:

Running: rake assets:precompile
rake aborted!
could not connect to server: Connection refused
Is the server running on host “127.0.0.1” and accepting
TCP/IP connections on port 5432?

This stackoverflow post helped to solve the issue. All you need to do is add the following line to your application.rb file:

#Applicication.rb
config.assets.initialize_on_precompile = false

Let me know if you have any problems.

Installing SQL Developer on Ubuntu – make-sqldeveloper-package chmod: missing operand after `755′

Hey everyone,

I was following a guide while trying to install SQL Developer on Ubuntu, however I ran into the following error:

make-sqldeveloper-package chmod: missing operand after `755′

 

To fix it, simply change line number #381 in ‘/usr/bin /make-sqldeveloper-package’ as follows:

Original

${FIND} "${OPTDIR}" ! ( -type d -o -name "*.jar" ) |${XARGS} ${XARGS_OPTS} ${FILE} ${FILE_OPTS} |${GREP} ${GREP_OPTS} "shell script text executable" |${CUT} ${CUT_OPTS_FUNC_CLEAN} |${XARGS} ${XARGS_OPTS} ${CHMOD} ${CHMOD_OPTS}

Modified

${FIND} "${OPTDIR}" ! ( -type d -o -name "*.jar" ) |${XARGS} ${XARGS_OPTS} ${FILE} ${FILE_OPTS} |${GREP} ${GREP_OPTS} "shell script" | ${GREP} ${GREP_OPTS} "text executable" |${CUT} ${CUT_OPTS_FUNC_CLEAN} |${XARGS} ${XARGS_OPTS} ${CHMOD} ${CHMOD_OPTS}

Thanks to this blog post for the solution, just note that it is Polish.

Let me know if you have any issues!