I have created a Docker/Podman Container Image with Jupyter Notebook installed on it. Please feel free to use it for your Python, Statistics, Numpy, GNU-Octave and SageMath work.

Github Source – Containerfile
Pre-Build Container on Docker Hub
Pre-Build Container on Quay.io
Installing Podman on Windows 11
Launching the Docker/Podman Container
Using Jupyter-Notebook
Good Video Series on SageMath
References
Final Thoughts & Feedback

GitHub Source – Containerfile

The Containerfile used to build this image is available on GitHub. It includes all necessary instructions to set up a lightweight environment with Jupyter Notebook and essential scientific computing tools. You can inspect, modify, or rebuild the image to suit your needs.
GitHub Repository – https://github.com/hammadrauf/jupyter-notebook

Pre-Built Container on Docker Hub

To save time, you can pull the pre-built image directly from Docker Hub. It’s ready to run and includes Python, Numpy, GNU-Octave, and SageMath pre-installed.

Visit the Docker Hub page for more details and tags: Docker Hub

Pre-Built Container on Quay.io

For those who prefer Quay.io, the same image is available there as well. It’s maintained in sync with the Docker Hub version.

Quay.io Repository

Installing Podman on Windows 11

Podman is a great alternative to Docker, especially for rootless containers. On Windows 11, you can install Podman via the ‘Winget’ or manually using the installer from the official site.
1. Download Podman from podman.io
2. Follow the installation instructions for Windows.

OR use Winget

C:\> winget install redhat.podman

3. Start the podman machine, as per instruction given above.

Launching the Docker/Podman Container

Once Podman or Docker is installed, launching the container is simple:

C:\> podman run -d -p 8888:8888 -v <local-notebooks-dir>:/workspace/notebooks docker.io/hammadrauf/jupyter-notebook
C:\> podman run -d -p 8888:8888 -v C://Users//XXX//jupyter-notebooks:/workspace/notebooks docker.io/hammadrauf/jupyter-notebook

Or with Docker:

C:\> docker run -d -p 8888:8888 -v <local-notebooks-dir>:/workspace/notebooks docker.io/hammadrauf/jupyter-notebook
C:\> docker run -d -p 8888:8888 -v C://Users//XXX//jupyter-notebooks:/workspace/notebooks docker.io/hammadrauf/jupyter-notebook

After launching, open your browser and navigate to to access Jupyter Notebook. It should be visible at http://127.0.0.1:8888 or http://localhost:8888 .

Using Jupyter Notebook

Inside the container, Jupyter Notebook provides access to multiple kernels:
• Python for general scripting and data analysis
• GNU-Octave for MATLAB-like syntax and numerical mathematics
• SageMath for MAPLE like advanced symbolic mathematics
You can create notebooks for each tool and switch kernels as needed.

Good Video Series on SageMath

If you’re new to SageMath or want to deepen your understanding, check out this excellent video series:
SageMath Tutorial Series on YouTube
It covers everything from basic algebra to symbolic computation and calculus.

References

• Jupyter Project
• SageMath Official Site
• GNU Octave
• Podman Documentation
• Docker Documentation

Final Thoughts & Feedback

This container is a great starting point for students, educators, and researchers working in scientific computing. Feel free to fork the GitHub repo, contribute, or share feedback!

“WebNode” is a IaC script to quickly build and deploy a PHP WordPress WebServer and Email Relay Host on a virtualized server and possibly copied over to an actual Physical Hard Disk. It is a work in progress…as I write these lines.

IaC

‘Infrastructure as Code’ or IaC is the process of managing and deploying System infrastructure on virtualized environments. In simple words it is a fancy name given to creating and editing Virtual Machines (and system services) using scripts and code.

IaC has some benefits and some limitations. Benefits include the fact that all this code can be saved in repositories and replayed automatically when needed. One limitation is that if some physical work is involved, that can not be expressed as code.

I started on my Ansible journey impressed by the work done by Jeff Geerling in Ansible (A system for automating repititive tasks as code) and also his Video Series on teaching Ansible. I forked his Packer-boxes Github repository to provide some latest Vagrant images for VirtualBox. Then learning from his Ansible videos, book, and other Ansible books, I am creating another Github repository that will create VirtualBox (and Cloud – Linode.com, Azure etc.) image named WebNode. WebNode will be a server that has Apache, MariaDB, PHP3, WordPress, and Postfix/Dovecot Email Relay software installed on it. Plus you will be able to bring your own WordPress Database into this node. It is still a work in progress.

Usefulness of Generic CI/CD System

CI/CD stands for Continuous Integration/Continuous Delivery. It refers to the concept of automating integration of minor developmental changes automatically into the bigger system along with automated testing. It also provides this successfully tested overall system ready for deployment to the end user, automatically deploying also if configured like so.

Terraform by itself is not a complete CI/CD tool. Any large scale deployment of Terraform/Ansible/Vagrant can not undermine the usefulness of generic CI/CD tools like Jenkins. Jenkins can provide the missing glue in your automated pipeline.

git clone https://github.com/build-boxes/webnode.git
cd webnode

It can be used in Windows 10/11 (a bit difficult to setup), or you can use Debian/Ubuntu host environemnt.

1. Install VirtualBox
2. Install Vagrant, Ansible (Use Windows Subsystem for Linux 2)
3. Install some plugins in WSL2 to allow Ansible and Vagrant to access Windows VirtualBox (Google Search, related link).
4. Change into the project root folder.
5. Download required roles with the following command:

   rm -rf ~/.ansible/roles/
   ansible-galaxy install --force -r ./roles/requirements.yml 

6. Run:

   vagrant up
   OR
   vagrant up debian

7. Now you can ssh into your Virtual server.

   vagrant ssh
   

8. Get the Local Network IP Address.

   ip a
   

10. Open the IP Address in Browser.

    

11. There is not much to see or test in the WebNode project itself, at this time, other than the page in previuos step. It is a work in progress. Follow the Github repository listed above for uptodate status.
12. To shutdown the VM, run:

    vagrant halt
    OR
    vagrant halt debian

13. To Destroy the VM,  run:

    vagrant destroy -f
    OR
    vagrant destroy debian -f

It can be used in Windows 10/11 (a bit difficult to setup), or you can use Debian/Ubuntu host environment.

1. Install Ansible, Terraform (Use Windows Subsystem for Linux 2)
2. Install some plugins in WSL2 for Ansible (Google Search, related link)
3. Change into the project root folder.
4. Download required roles with the following command:

   rm -rf ~/.ansible/roles/
   ansible-galaxy install --force -r ./roles/requirements.yml

5. Change into one of the”tf-linode*” or “tf-azure*” subfolders
6. Run:

   terraform init
   terraform plan
   terraform apply -auto-approve

7. To Destroy run:

   terraform destroy -auto-approve

Using the VirtualBox Images

Apart for use in the WebNode project above, the VirtualBox images can be used for other tasks also. Make sure Vagrant and Oracle VirtualBox are installed. Start by obtaing the Vagrantfile automatically as follows:

$ vargrant init raufhammad/centos9

OR

C:\> vargrant init raufhammad/centos9

This will show output like below:

C:\Users\XYZ>mkdir temp

C:\Users\XYZ>cd temp

C:\Users\XYZ\temp>vagrant init raufhammad/centos9
A `Vagrantfile` has been placed in this directory. You are now
ready to `vagrant up` your first virtual environment! Please read
the comments in the Vagrantfile as well as documentation on
`vagrantup.com` for more information on using Vagrant.

Once the Vagrantfile is downloaded, you may modify this file as per your needs, before the next step.

From the same box directory, run the following command after the Vagrantfile has been downloaded:

$ vagrant up

$ vagrant destroy -f

References

1. The WebNode project repository (Work in progress…), https://github.com/build-boxes/webnode , Date Accessed: April 18, 2024
2. Jeff Geerlings original Packer-Boxes Github Repository, https://github.com/geerlingguy/packer-boxes , Date Accessed: April 18, 2024
3. My fork from the above with updated Packer-Boxes, https://github.com/build-boxes/packer-boxes , Date Accessed: April 18, 2024
4. Ready built VagrantUp.com (Vagrant boxes) repository, https://app.vagrantup.com/raufhammad , Date Accessed: April 18, 2024
5. Install Oracle VirtualBox Link, https://www.virtualbox.org/wiki/Downloads , Date Accessed: April 18, 2024
6. Install Vagrant link (Install in wsl2 in Windows) , https://developer.hashicorp.com/vagrant/install , Date Accessed: April 18, 2024
7. Install Terraform link, https://developer.hashicorp.com/terraform/install , Date Accessed: April 18, 2024
8. Install Ansible guide link, https://docs.ansible.com/ansible/latest/installation_guide/intro_installation.html , Date Accessed: April 18, 2024
9. Install Ansible in WSL2, https://4sysops.com/archives/install-ansible-on-windows/ , Date Accessed: April 18, 2024
10. Using Windows VirtualBox from Ansible in WSL2 – Tricks, https://slavid.github.io/2021/11/28/running-vagrant-ansible-windows-through-wsl2/#configuration , Date Accessed: April 18, 2024
11. Book – Ansible: Up and Running (3rd Edition), Bas Meijer, Lorin Hochstein, and Rene Moser, Published by O’Reilly Media Inc, July 2022. Website: https://www.oreilly.com/library/view/ansible-up-and/9781098109141/, https://www.ansiblebook.com/
12. Jeff Geerling (GeerlingGuy) Ansible Video Series, https://www.youtube.com/playlist?list=PL2_OBreMn7FqZkvMYt6ATmgC0KAGGJNAN , Date Accessed: April 18, 2024
13. Custom Ansible Roles:
    • What are Ansible-Roles? Date Accessed: May 11, 2024
    • hammadrauf.sudousers – https://github.com/hammadrauf/sudousers/tree/main – Date Accessed: May 11, 2024
    • hammadrauf.apache2 – https://github.com/hammadrauf/apache2 – Date Accessed: May 11, 2024
      1. hammadrauf.apache_vhosts – https://github.com/hammadrauf/apache_vhosts
14. Jenkins Tutorial, https://www.jenkins.io/doc/tutorials/, Date Accessed: July 12, 2024

This is related to an old post. This time I have translated it from C/C++ to Java and modified it a little bit. Now it takes as input additional parameters of currency-Note, currency-Coin and coin-Places. It is open sourced under Apache Software license 2.0. Source code can be found on Github.

Number-to-Words-in-Java is a program that takes as input a number and outputs the same number in English words form. It will be useful in situations like Bank Cheque printing. I was able to embed it in a Jaspersoft Studio Report, as shown in screen shots below.

Parameters Explained

In use inside – Jaspersoft Studio Report

References

1. The old post for C/C++ Function, https://andromedabay.ddns.net/number-to-words-recursive/, Date Accessed: March 28, 2024
2. The old C/C++ Function, http://codepad.org/C29M1wUQ, Date Accessed: March 28, 2024
3. Github repository for this (Java) Method, https://github.com/hexword-ca/NumberToWords, Date Accessed: March 28, 2024

In BASH shell (Linux operating system or Windows 10 [See below] ) when you are running a server of some kind often you are faced with a situation where the log folder gets filled up with old copies of the log files. Some Server software provide tools for automatic removal of old log files, but at other times you may not be that lucky. I recently faced a similar situation but after some Web-searching and experimentation came up with a solution using a single line Bash Command. If your software does not have automatic roll over capability for log files, then probably you can put the following script in your cron-jobs or Task Scheduler.

The basic command is given below:

ls -t | tail -$( expr `ls -t | wc -l` - 4 ) | xargs rm -Rf
# The above command will keep 4 latest files, N = 4

Let us break it down in parts and study it for a while.

ls -t

This command lists out the file names in a folder by order of modified date, the newest files are shown first, then older files.

ls -t | wc -l

The ‘|’ character is the PIPE symbol, it passes output from the command on the left to the command on the right. The command on the right word-count with -l option, which counts the number of lines. So in all this command will count the number of files in the directory.

$( expr `ls -t | wc -l` - 4 )

The ‘$’ symbol has multiple uses. In this case it is being used to evaluate an expression (Expression as in arithmetic). Infact there are 2 expressions here. The inner Expression is marked by the BASH-keyword ‘expr’ and enclosed in back-tics characters (`). The inner expression is calculating the total number of files in the directory. The outer Expression is subtracting N (N=4 in our example). So the outer expression is calculating 4 less than the total number of files in the directory.

tail -$( expr `ls -t | wc -l` - 4 )

The tail command is often used as the right hand side in a PIPE command. Tail command displays the last part of a file or stream. The above tail command is actually “tail -X” where X can be any integer. It will show the last X lines of the File or input stream. So in our expression it will show the last part of the file or input stream, leaving aside the top 4 (N) latest files.

ls -t | tail -$( expr `ls -t | wc -l` - 4 )

The above command now makes more sense, as the Input Stream or file list is now included. “ls -t” on the left side of the | (PIPE) symbol is trying to list all files but then the right side of the Pipe “tail -$( expr ls -t | wc -l – 4 )” is only tailing the last so many files, leaving the top 4 latest files. So this command is generating the list of files we want to delete, in the next step.

ls -t | tail -$( expr `ls -t | wc -l` - 4 ) | xargs rm -Rf

Now since we can list the names of the files we want to delete, let us PIPE in another command to delete them. “xargs rm -Rf” is doing exactly that. The actual delete files command is “rm -Rf”, which deletes all files forcing the delete with recursive options. “xargs” is a way in BASH shell to pass arguments to commands via a PIPE.

Changing Directories Before and After the Command

The command above can be modified to Change into a target directory, then delete all but 4 latest files, and then change back into home folder. The following command does exactly that.

cd /home/hammad/test && ls -t | tail -$( expr `ls -t | wc -l` - 4 ) | xargs rm -Rf && cd ~

How to Run it in Windows 10?

If you have enabled and installed “Windows Subsystem for Linux” then you can run the above and many other BASH commands in Windows 10 also. A good reference article link is given here and below in Further Reading section. Another link given in further reading section, Article 3 Link, shows how to access Windows folders from Linux Sub-system in Windows 10.

Further Reading

1. How to Use Linux Bash Shell on Windows 10. Article 1 Link, Date accessed August 14, 2021.
2. WC Command Examples to Count Number of Lines….. , Article 2 Link, Date accessed August 14, 2021.
3. Access Windows files from Linux subsystem, Article 3 Link, Date accesses August 14, 2021.