tutorial – Richard Callaby

A brief tutorial on how to use SSH

Secure Shell (SSH) is a protocol that provides secure access to remote computers over an unsecured network. It provides a secure channel for communication between two untrusted hosts over an insecure network. SSH is widely used for remote administration of servers and other systems.

SSH works by encrypting all data that is transmitted between the two hosts. This includes the login credentials, commands, and any data transmitted between the two hosts. The encryption ensures that the data is protected from eavesdropping, interception, and tampering.

SSH can be used for a variety of tasks such as:

Logging into a remote server to perform administrative tasks
Copying files between two computers using scp (secure copy)
Running a command on a remote server using ssh

Using SSH to Connect to a Remote Server:

The first step in using SSH is to connect to a remote server. To do this, you’ll need to know the IP address or domain name of the server, as well as your username and password. Once you have this information, you can open a terminal on your local machine and use the following command:

ssh username@server_ip_address

This command will initiate an SSH connection to the remote server with the specified username. You will be prompted to enter the password for the specified user account. Once you’ve entered the correct password, you will be logged in to the remote server.

If you’re connecting to the server for the first time, you may see a message similar to the following:

The authenticity of host 'server_ip_address (server_ip_address)' can't be established.
RSA key fingerprint is SHA256:XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX.
Are you sure you want to continue connecting (yes/no)?

This message is asking you to verify that you trust the remote server. The RSA key fingerprint is a unique identifier that is used to verify the identity of the remote server. If you trust the remote server, you can type “yes” to continue connecting. If you do not trust the remote server, you should type “no” and investigate the issue further.

Copying Files with SCP:

SSH also provides a secure way to copy files between two computers using the scp (secure copy) command. The syntax for scp is similar to that of the cp (copy) command:

scp source_file username@server_ip_address:/destination/path/

This command will copy the source_file to the specified destination path on the remote server. You will be prompted to enter the password for the specified user account.

Running a Command on a Remote Server:

SSH can also be used to run a command on a remote server. This is useful for performing tasks that require administrative privileges or that are easier to perform on the remote server. To run a command on a remote server, use the following command:

ssh username@server_ip_address 'command'

Replace “command” with the command you want to run on the remote server. The output of the command will be displayed in your local terminal.

Conclusion:

SSH is an essential tool for remote system administration and secure file transfer. It provides a secure channel for communication between two untrusted hosts over an insecure network. With SSH, you can connect to a remote server, copy files between two computers, and run commands on a remote server securely

Using Django Codespaces in GitHub – A How To Guide with GitHub Actions

Django Codespaces is a feature of GitHub that allows developers to create a cloud-based development environment for their Django projects. This means that you can write code, test it, and deploy it without leaving GitHub. In this article, we will go over the steps to create a Django Codespace on GitHub and use GitHub actions to automate some of the tasks.

Creating a Django Codespace on GitHub

To create a Django Codespace on GitHub, follow these steps:

Create a new repository: Navigate to your GitHub account and create a new repository. Give it a name and a brief description.
Enable Codespaces: Go to the settings of your repository and select the “Codespaces” tab. Click on the “Enable Codespaces” button.
Choose a configuration: You will be prompted to choose a configuration file for your Codespace. GitHub provides some preconfigured templates, but you can also use your own custom configuration. For Django projects, we recommend using the “Python” configuration.
Create a Codespace: Once you have selected your configuration file, you can create your Codespace by clicking on the “New Codespace” button. This will create a new cloud-based development environment for your Django project.
Start coding: Now that your Codespace is set up, you can start coding. You can access your Codespace by clicking on the “Open in Codespaces” button on your repository’s main page.

Using GitHub Actions to Automate Tasks

GitHub Actions is a powerful tool that allows developers to automate tasks such as building, testing, and deploying their code. Here are some examples of how you can use GitHub Actions to automate tasks for your Django project:

Running Tests: To run tests automatically every time you push code to your repository, you can create a GitHub Action that uses the Django test runner. Here’s an example configuration file:

name: Run Tests

on:
  push:
    branches:
      - main

jobs:
  test:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout Code
        uses: actions/checkout@v2
      - name: Set up Python
        uses: actions/setup-python@v2
        with:
          python-version: '3.9'
      - name: Install Dependencies
        run: pip install -r requirements.txt
      - name: Run Tests
        run: python manage.py test

This configuration file sets up a job that runs on every push to the “main” branch. It checks out the code, sets up Python, installs dependencies, and runs the tests using the Django test runner.

Deploying to a Server: To automatically deploy your Django project to a server every time you push code to your repository, you can create a GitHub Action that uses a deployment tool such as Ansible. Here’s an example configuration file:

name: Deploy to Server

on:
  push:
    branches:
      - main

jobs:
  deploy:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout Code
        uses: actions/checkout@v2
      - name: Install Dependencies
        run: pip install -r requirements.txt
      - name: Deploy
        uses: appleboy/ansible-action@v1
        with:
          playbook: deploy.yml
          inventory: production
          become: yes
          extra-vars: |
            server_user={{ secrets.SERVER_USER }}
            server_host={{ secrets.SERVER_HOST }}
            server_port={{ secrets.SERVER_PORT }}

This configuration file sets up a job that runs on every push to the “main” branch. It checks out the code, installs dependencies, and deploys the

Git Merge vs Git Rebase vs Git Squash – Understanding the differences.

Git is a powerful version control system that allows developers to collaborate on code and track changes to it over time. One of the key features of Git is the ability to merge, rebase, and squash commits. These commands allow developers to manipulate the commit history of a repository and make it easier to collaborate with others.

Git merge is used to combine multiple branches into a single branch. When you run the command git merge, Git will take the changes from one branch and apply them to another branch. For example, if you are working on a new feature in a branch called “feature-branch” and you want to merge those changes into the “master” branch, you would run the command git merge feature-branch. This will take all the changes that were made in “feature-branch” and apply them to the “master” branch.

Git rebase is similar to git merge, but it works a little differently. Instead of applying changes to another branch, git rebase takes the commits from one branch and applies them to the base of another branch. This can make your commit history look cleaner, as all the commits are grouped together. For example, if you are working on a feature branch and you want to rebase the commits onto the “master” branch, you would run the command git rebase master. This will take all the commits from your feature branch and apply them to the “master” branch.

Git squash is a command that allows you to combine multiple commits into a single commit. This can be useful when you want to clean up a messy commit history or when you want to make a single, atomic change. For example, if you have made several commits on a feature branch and you want to squash them into a single commit, you would run the command git squash. This will combine all the commits into a single commit with a new commit message.

When to use git merge, git rebase, and git squash depends on your specific use case.

Git merge is best used when you want to combine changes from multiple branches into a single branch. It’s a simple way to merge changes without altering the commit history.

Git rebase is best used when you want to clean up a messy commit history or when you want to make a single, atomic change. It’s a good option when you want to keep your commit history clean and easy to understand.

Git squash is best used when you want to combine multiple commits into a single commit. This is a good option when you want to make a single, atomic change or when you want to clean up a messy commit history.

It is important to note that git merge and git rebase should be used with care, particularly when working on a shared repository with other people. If you use git merge or git rebase, it can cause conflicts and make it difficult for other people to work on the repository.

It is also important to note that when you squash commits, you lose the commit message, so it is best not to use git squash when working on a shared repository with other people.

In conclusion, git merge, git rebase, and git squash are powerful commands that can help you manage your code and collaborate with others. However, it is important to understand the difference between these commands and when to use them in order to avoid conflicts and other issues. In summary, git merge is best when combining multiple branches, git rebase is best when cleaning up commit history and git squash is best when combining multiple commits into a single commit

Git cherry-pick command – How and Why to Use It

Git CherryPick is a powerful command that allows developers to select specific commits from one branch and apply them to another branch. This can be useful in situations where you want to merge specific changes from one branch into another, without merging the entire branch.

To use Git CherryPick, you first need to switch to the branch where you want to apply the changes using the command “git checkout [branch name]”. Then, you can use the command “git cherry-pick [commit hash]” to apply the changes from the specified commit.

It is important to note that when you use Git CherryPick, it applies the changes as a new commit on the current branch, rather than merging the entire branch. This means that the commit history of the original branch is not preserved in the new branch.

One of the main use cases for Git CherryPick is when you have made changes on a feature branch that you want to merge into your main development branch, but you only want to include certain commits. This can be useful in situations where you have made multiple commits on a feature branch, but not all of them are ready to be merged into the main branch.

Another use case for Git CherryPick is when you have made changes to a branch that are dependent on other changes that have not yet been merged into the main branch. In this case, you can use Git CherryPick to apply the dependent changes to the main branch, while the other changes are still being reviewed.

On the other hand, Git CherryPick should not be used in situations where you want to merge an entire branch into another branch. In this case, it is better to use the “git merge” command, which will preserve the commit history of the original branch.

Additionally, you should be careful when using Git CherryPick in situations where the commits you are picking depend on other commits that have not been picked yet. In this case, you may end up with conflicts or errors in your code. It is recommended to use Git CherryPick with caution and to thoroughly test the changes before merging them into the main branch.

In conclusion, Git CherryPick is a powerful command that allows developers to select specific commits from one branch and apply them to another branch. It can be useful in situations where you want to merge specific changes from one branch into another, without merging the entire branch. However, it should be used with caution and not in situations where you want to merge an entire branch or commits that depend on other commits.

Git and GitHub – Common Questions You May Have.

As a software developer, you will likely encounter many questions when it comes to using Git and GitHub for version control and collaboration. In this article, we’ll discuss some common questions that developers may have about using Git, and explain how to effectively use pull requests and branches as part of the development process.

First, let’s start with the basics of Git. Git is a distributed version control system that allows developers to track changes made to their code and collaborate with other developers on the same codebase. Git is a command-line tool, but there are also many graphical user interfaces (GUIs) that can be used to interact with Git.

One common question that developers may have is, “Why should I use Git?” The answer is simple: Git allows you to keep track of changes to your code, collaborate with other developers, and easily roll back to previous versions of your code if something goes wrong. This is especially important when working on large, complex projects with multiple developers.

Another question that developers may have is, “How do I get started with Git?” The first step is to install Git on your computer. Once Git is installed, you can create a new repository on your local machine by running the command “git init.” This will initialize an empty Git repository in the current directory.

Once you have a Git repository set up, you can start making changes to your code and committing those changes to the repository. Each time you make a change and want to save it, you will run the command “git commit” followed by a message describing the change. This will save a new version of the code in the repository.

Now, let’s talk about how to use pull requests and branches when working with Git and GitHub.

When working on a team, it is common to use branches in Git to separate the development of different features or bug fixes. This allows developers to work on their own separate branches and then merge their changes back into the main branch when they are ready. This makes it easier to test and review changes before they are incorporated into the main codebase.

When a developer finishes working on a feature or bug fix, they will create a pull request. A pull request is a way for developers to request that their changes be merged into the main branch. The pull request will contain a description of the changes made, and other developers can review the code and make comments before it is approved and merged.

One question that developers may have when working with pull requests is, “How do I review code in a pull request?” To review code in a pull request, you can view the changes that were made and make comments on specific lines of code. This allows other developers to see your feedback and make any necessary changes before the code is merged.

Another question that developers may have is, “What is the difference between a pull request and a merge request?” Both pull requests and merge requests are used to request that changes be incorporated into the main branch, but the terminology can vary depending on the platform. Pull requests are used on GitHub, while merge requests are used on GitLab.

Finally, one common question that developers may have when working with Git and GitHub is, “How do I resolve conflicts when merging branches?” Conflicts can occur when changes made on one branch conflict with changes made on another branch. To resolve conflicts, you will need to manually edit the code to resolve the conflicts and then commit the changes. You can then proceed with the merge.

In summary, Git is a powerful tool that allows developers to track changes to their code and collaborate with others on the same codebase. By using pull requests and branches, developers can easily review and merge changes into the main codebase. By understanding how to use these features, developers can work more efficiently and effectively as a team.

When working with Git and GitHub, it is important to understand the basics of Git, including how to create and manage repositories, commit changes, and view the history of a repository. Additionally, it is important to understand the use of branches, pull requests, and merge requests.

Branches are a powerful feature in Git that allows developers to work on separate features or bug fixes without interfering with the main codebase. This makes it easy to test and review changes before they are incorporated into the main branch.

Pull requests are a way for developers to request that their changes be merged into the main branch. Other developers can then review the code and make comments before it is approved and merged. This allows for a more collaborative and efficient development process.

It is also important to understand how to resolve conflicts when merging branches. Conflicts can occur when changes made on one branch conflict with changes made on another branch. To resolve these conflicts, developers will need to manually edit the code and then commit the changes.

In addition to these concepts, it’s important to have a good understanding of common Git commands and how they are used such as git clone, git push, git pull, git branch, git checkout and etc. also understanding the structure and behavior of git repository and branches. Regularly practicing with Git and familiarizing yourself with its features will help you to become more efficient and effective as a software developer.

Overall, Git and GitHub are essential tools for software development. By understanding how to use these tools effectively, developers can work more efficiently and effectively as a team. Through the use of branches, pull requests, and merge requests, developers can easily review and merge changes into the main codebase, resulting in a more collaborative and efficient development process.

Understanding .bashrc in the GNU/Linux OS.

The bashrc file is a script that is run every time you start a new terminal session in a Linux operating system. It is responsible for setting up your terminal environment and defining any customizations or aliases that you may have defined.
To customize your bashrc file, you will first need to open it in a text editor. This can typically be done by typing nano ~/.bashrc into the terminal. If you prefer to use a different text editor, such as vi or emacs, you can substitute it in place of nano.
One common customization that many users make to their bashrc file is to define aliases for frequently used commands. For example, you might define an alias for ls -al as la, so that you can simply type la to see a detailed listing of the contents of a directory. To define an alias, you can use the alias command in your bashrc file, like so:

alias la='ls -al'

Another useful customization that you can make to your bashrc file is to set up custom prompt strings for your terminal. By default, the prompt string will typically include your username, the name of the current directory, and a $ symbol, but you can customize this to include any information that you find useful. For example, you might want to include the current time, the current git branch, or the status of your background jobs. To customize your prompt string, you can use the PS1 variable, like so:

PS1='\u@\h:\w$ '

This will set your prompt string to include your username, the name of the current host, and the name of the current working directory. You can use various escape sequences to include other information, such as \t for the current time or \j for the number of background jobs.

Another useful customization that you can make to your bashrc file is to set up custom functions. Functions are essentially small scripts that you can define and then call by name from the terminal. This can be useful for automating repetitive tasks or for encapsulating complex commands into a simpler interface. To define a function, you can use the function keyword, like so:

function hello { echo "Hello, world!" }

You can then call this function by typing hello into the terminal. Functions can also accept arguments, which can be accessed within the function using the $1, $2, etc. variables.

In addition to the customizations that you can make directly in your bashrc file, you can also include other script files or configuration files from within your bashrc file. This can be useful if you want to keep your customizations organized or if you want to reuse the same customizations across multiple machines. To include another script or configuration file, you can use the source command, like so:

source ~/.my_custom_configurations

There are many other customizations that you can make to your bashrc file, and the exact steps will depend on your specific needs and preferences. Some other examples of customizations that you might consider include setting up custom key bindings, setting up environment variables, or configuring command history.

In summary, the bashrc file is a powerful tool for customizing your terminal environment in a Linux operating system. By defining aliases, custom prompt strings, functions, and other customizations, you can