Megan Coyle

May 23, 2023January 16, 2024

Essential Command Line Commands for Developers

The command line interface (CLI) is a powerful tool that developers can leverage to streamline their workflow and boost productivity. While graphical user interfaces (GUIs) are user-friendly, the command line offers a more efficient and flexible way to interact with your computer.

Here are some useful commands to keep in your developer toolbox:

Navigating the File System:
- cd <directory>: Change directory. Use this command to navigate between folders (add the directory path in the place of <directory>).
- ls: List the contents of a directory. Add options like -l for a detailed list or -a to show hidden files.
- pwd: Print working directory. Prints the file path of the directory you’re currently in.
File Operations:
- cp: Copy files or directories. Helpful for duplicating files (use cp <file> <directory> to copy a file to a directory – which can possibly overwrite files).
- mv: Move or rename files and directories (to move files, use mv <file> <directory>, to rename a file, use mv <file-old> <file-new>).
- rm: Remove files or directories (rm <file> for files or rm -r <directory> for directories). Exercise caution, as this command is irreversible.
- mkdir <directory>: Create a directory (add the name of the directory in place of <directory>).
- touch <file>: Create a file (add the file name in place of <file>).
Text Manipulation:
- cat <file>: Concatenate and display the content of files.
- grep: Search for specific patterns in files.
- sed: Stream editor for filtering and transforming text.
File Inspection:
- file: Determine the file type.
- wc: Count words, lines, and characters in a file.
- head and tail: Display the beginning or end of a file.
System Information:
- df: Display disk space usage.
- free: Display amount of free and used memory.
- top and htop: Show real-time system statistics.
Version Control:
- git: Essential for version control. Commands like git clone, git pull, git push, and more are crucial for collaborative development.
Package Management:
- npm or yarn (for Node.js): Manage packages and dependencies for JavaScript projects.
- pip (for Python): Install Python packages effortlessly.
Network-related Commands:
- ping: Test the reachability of a host.
- curl and wget: Download files from the web directly in the terminal.
Process Management:
- ps: Display information about active processes.
- kill: Terminate a process. Use with caution.
User and Permissions:
- sudo: Execute a command with superuser privileges.
- chown and chmod: Change ownership and permissions of files.

Mastering the command line is a key skill for developers. These essential commands empower developers to perform a wide range of tasks efficiently and are particularly valuable in server environments and automation scripts. As you become more comfortable with the command line, you’ll discover its potential for enhancing your development workflow and troubleshooting capabilities.

April 4, 2023January 13, 2024

What is Load Balancing?

Load balancing is all about making sure no single server gets overwhelmed. Picture this: your favorite website or app can get crazy busy at times. Without load balancing, one server might end up feeling like it’s carrying the weight of the world, leading to slow response times or even crashing.

So, what does load balancing do? It’s like a traffic cop for network requests, spreading them out among multiple servers. This way, no server gets too bogged down, and everything runs smoothly.

Load Balancing Algorithms

Round Robin: Servers take turns handling requests.
Least Connections: The server with the least load (fewest active connections) gets first dibs on new requests.
Weighted Round Robin: This one’s like Round Robin, but servers can have different “weights” based on their capacity – heavier servers get more requests.
Least Response Time: Sends traffic to the server that’s quickest to respond – it’s all about efficiency.
Hash: Distributes requests based on a key you define, whether it’s the client’s IP address or the request URL. If the set of servers changes, NGINX Plus can even apply a consistent hash to minimize the reshuffling of workloads.
IP Hash: The IP address of the client decides which server gets the special treatment. So, when a request comes in, the server is chosen based on the client’s IP address.
Random with Two Choices: This one randomly picks two servers and then makes a smart move. It applies the Least Connections algorithm to decide which server gets the request.

Benefits of Load Balancing

Scalable
Reduces downtime
Flexible
Efficient

Whether it’s at the application layer, transport layer, or network layer, load balancing ensures everything is running smoothly.

March 28, 2023January 4, 2024

GitHub Tips and Tricks

GitHub is a developer platform that allows developers to create, store, and manage their code. If you’re new to GitHub, or if you’ve been using it for years and have yet to look into shortcuts, I figured I’d share a few handy GitHub tips and tricks.

GitHub Keyboard Shortcuts

If you navigate to a repo page, and press ? (or Shift + /) GitHub will show you a modal with a list of quick keyboard shortcuts, as well as a link that displays all the available shortcuts.

One of my favorite ones to use is typing / or s when you’ve navigated to a repo page, since it allows you to pull up the file search.

Autodelete GitHub Branches

You can automatically delete GitHub branches after pull requests have been merged into your repo. This is great for managing your repo’s branches so that they don’t get out of control. To set up the automatic deletion of branches, navigate to the settings for a specific repo. On the “General” settings page, under the “Pull Requests” section, select “Automatically delete head branches.”

Link to Specific Lines of Code in a GitHub Repo

If you click the number beside a line of code, it will highlight the line and display a few menu options. If you click “Copy permalink” you’ll have access to a link that will link to the code snippet even if the file is later updated or deleted on the main branch. If you hold down shift while selecting lines of code, you can select several lines to highlight and link to.

Close GitHub Issues Automatically with Keywords in your Commit Messages

You can automatically close issues fixed by commits by using a keyword followed by the issue number in the commit message, i.e. git commit -m "fixes #30"

Here’s a list of all the keywords you can use to automatically close issues:

close #30
closed #30
closes #30
fix #30
fixed #30
fixes #30
resolve #30
resolved #30
resolves #30

Handy GitHub URLs

GitHub uses a few URL patterns that are handy for getting access to diffs of code or even user avatars:

Avatars: https://github.com/<username>.png
Diff of a commit: https://github.com/<repo-owner>/<repo>/commit/<sha>.diff
Patch of a commit: https://github.com/<repo-owner>/<repo>/commit/<sha>.patch
Diff of a pull request: https://github.com/<repo-owner>/<repo>/pull/<id>.diff
Patch of a pull request: https://github.com/<repo-owner>/<repo>/pull/<id>.patch
Latest release: https://github.com/<repo-owner>/<repo>/releases/latest

Format your GitHub README.md with Markdown

When visiting a GitHub repo, GitHub will serve the repo’s README.md. You can make these documents pretty elaborate by including a project overview, info on how to run the project locally, deployment info, etc. I like to use a project’s repo as the single source of truth for that project and keep it updated as processes change and as adjustments are made to various environments. You can find some basic markdown formatting info via GitHub’s documentation. One helpful tip for markdown formatting that I enjoy using, is that the <details></details> tags allow you to hide/show content via a simple accordion.

Host Web Pages and Simple Applications with GitHub Pages

You can host a GitHub Pages site for free via your GitHub account. This is great for simple websites and applications. You can even customize the domain URL, but the out-of-the-box URL is <your-github-username>.github.io/<repo-name>. You can find out more about using GitHub pages here.

January 24, 2023December 29, 2023

What is the Difference Between null, NaN, and undefined in JavaScript?

The other day I was thinking about how earlier last year, I was interviewing like crazy, and sometimes I had recruiter phone screens where I was quizzed on various JavaScript terms. As I think of some of the questions I’ve been asked previously, I plan to write articles focusing on these questions and answers.

NaN

NaN means Not a number, and it denotes the value of an object is not a number. If you look at typeof NaN it will return 'number' since NaN is a numeric data type that is undefined as a real number. NaN can be returned if you do one of the following:

Convert undefined into a number
Convert a non-numeric string into a number
Divide zero by zero
Divide infinity by infinity
Operation where the result is not a real number
Method/expression’s operand is or gets coerced to NaN

null

null means the object is empty. It’s an assignment value that can be assigned to a variable that has no value.

undefined

undefined means that the object doesn’t have any value and is undefined. This happens when you declare a variable and don’t assign a value to it.

December 10, 2022December 28, 2023

How to update Node to the latest version?

Node.js is a JavaScript runtime environment that runs on the V8 JavaScript engine and executes JS code outside a web browser. When developing locally, you’ll want to ensure that you keep Node updated for various projects to ensure you’re protecting applications from vulnerabilities and bugs.

NVM is a great tool for installing different versions of Node and switching between different versions for various projects. You’ll first want to install NVM. Once installed, you can install versions by doing the following:

Run nvm install [version] within the command line (replacing [version] with the version of Node you’d like to install).

Useful NVM commands

// check version of Node
node -v // can also use node --version

// list all locally installed versions of Node
nvm ls

// install specific version of Node
nvm install 20.10.0

// set default version of Node
nvm alias default 20.10.0

// switch version of Node
nvm use 20.00.0

// install latest stable version of Node
nvm install stable

How to specify what version of Node to use in a specific project

Within a project’s root directory, you can specify the version of Node that NVM should load by creating a .nvmrc file. You can generate this file by running the following command in the project’s root directory: node --version > .nvmrc

November 10, 2022December 26, 2023

How to update dependencies in your package.json?

To update dependencies in package.json files, you can use npm, the package manager for Node.js:

In the terminal, navigate to the root directory of your project and run npm install or npm i to install all the dependencies in your package.json
To update a specific dependency, run npm update package-name (package-name is the name of the dependency you want to update, so adjust that text within this command).
To update all dependencies, run npm update

To update npm itself, run the following:

npm install -g npm@latest

November 8, 2022December 28, 2023

Useful Regular Expressions for Developers

A regular expression, or regex, is a sequence of characters that specifies a match pattern in text. Often times regex is used for form validations and string-searching algorithms. Here are a few regex that are handy for developers:

Letters

Domain: ^([a-z][a-z0-9-]+(\.|-*\.))+[a-z]{2,6}$
Email: ^[_]*([a-z0-9]+(\.|_*)?)+@([a-z][a-z0-9-]+(\.|-*\.))+[a-z]{2,6}$
Letters only: ^[a-zA-Z]+$

Numbers

Numbers only: ^[0-9]*$
Positive numbers: ^\d*\.?\d+$
Negative numbers: ^-\d*\.?\d+$
Numbers with spaces and parenthesis: /^(?:\+\d{1,3}|0\d{1,3}|00\d{1,2})?(?:\s?$\d+$)?(?:[-\/\s.]|\d)+$/
Phone number: ^\+?[\d\s]{3,}$
Phone number with code: ^\+?[\d\s]+\(?[\d\s]{10,}$

Useful for Inputs

Letter and numbers only: ^[A-Z0-9]+$
Match blank input: ^\s\t*$
Match no input: ^$
Match new line: [\r\n]|$
Match URL: ^http\:\/\/[a-zA-Z0-9.-]+\.[a-zA-Z]{2,3}$
Match white space: ^\s+$
Match multiple white space: ^.\s{2,}.$

October 25, 2022January 4, 2024

Handy Git Commands

Git is a version control system that tracks changes in a set of files, which is used by developers to coordinate work done for various projects. Here are some useful git commands that can help with your workflow:

General Commands

git status to see what changes have been made locally
git add . to commit all locally edited files in the repo
git add <file> to add a file to the next commit
git rm <file> to delete a file in the next commit
git mv <file> to rename a file in the next commit
git add -p is useful if you’ve done too much work for one commit, ? is a useful command to print all
git cat-file -p <sha> prints the contents of blobs (sha refers to the SHA or hash that git assigns to each commit)
cat .git/HEAD to see what HEAD is pointing to

Stashing

Stashing your work is useful if you’re moving between branches when you’re in the middle of work. It’s a safe, non-destructive way to save your work.

git stash to save uncommitted work
git stash list to view the current stashes that are available
git stash apply applies the last stash
git stash apply stash@{0} to apply a specific stash (in place of the 0 you can add the number associated with the stash from your git stash list that you’d like to apply)
git stash --include-untracked to keep untracked files in your stash
git stash save "WIP: working on recent bug fix" in place of the text in the quotes here, you can add a name for easy references when viewing the list of your stashes and figuring out which stash to apply on your current branch
git checkout <stash name> -- <filename> grabs a single file form a stash
git stash show stash@{2} to show the files changed

Keeping Your Stash Clean

git stash drop to remove the last stash
git stash clear to remove all stashes

Logging

git log to view an overview of the most recent git commits
git log --since="yesterday" to view commits from a specific time period. You can also pass arguments like git log --since="2 weeks ago"
git log --name-status --follow -- <file> to log files that have been moved or renamed
git log --diff-filter=R --find-renames to find files that have been renamed
git show <commit> to show commit and its contents
git show <commit> --stat show files changed in commit
git show <commit>:<file> look at a file from another commit

Fixing Mistakes

git checkout -- <file-path> overwrites the working area file with the staging area version from the last commit (this operation overwrites without warning so use with caution)
git clean will clear your working area by deleting untracked files (this operation cannot be undone). Use the --dry-run flag to see what will get removed
git reset moves the HEAD pointer, modifies files for commits (can change history)
git revert <commit> is the safe reset (creates a new commit that introduces the opposite changes from the specified commit, the original commit stays in the repo)
git reset --hard HEAD use this command if your staging area has gotten really messed up and you want to blow away all of your local work
git commit --amend if you need to amend your latest commit
RERERE (Reuse Recorded Resolution) is a tool that remembers a previously used solution for a merge conflict. Set git config rerere.enabled true within a project to have access to this tool. You can also set it globally with git config --global rerere.enabled true

Rebasing

Rebasing your feature branch with main will help keep your development work up-to-date with the latest changes that have been committed to the repo. This will help make merge conflicts more manageable whenever it’s time to merge in your feature work.

git rebase main makes history of current branch cleaner and makes managing merge conflicts easier
git rebase -i <commit to fix> addressing specific commits

Working with GitHub

git clone <project reference to clone a GitHub repo locally
git pull performs a git fetch && git merge to ensure the latest version of a branch has been updated on your machine
git push origin <name-of-branch> to push any changes to the remote repo
git pull --rebase will fetch, update your local branch to a copy of the upstream branch, then replay any commits you made via rebase (this doesn’t work well on branches with local merge commits, it works best when branching off master and working on a feature)

Local Destructive Operations

When performing a destructive operation, make sure you properly stash your work so you don’t accidentally delete any of your work in progress. Use git stash --include-untracked to include working area changes in your stash.

git checkout --<file> if file is presnt in staging, it will be overwritten
git reset --hard overwrite changes that are staged and in working area
rebase, amend, and reset can rewrite history (if your code is hosted or shared, never run git push -f which forces a push of your changes)

Configuring Your Editor

To customize which editor git opens when you run a commit with no -m flag, a merge, or rebase, run the following command:

git config --global core.editor <your_editor>

In the place of <your_editor>, add the command associated with your editor of choice:

atom: atom --wait
emacs: emacs
sublime: subl -n -w
vi: vi or vim
vscode: code --wait

October 18, 2022October 18, 2022

How to Manage State by Using the React Context API

When I work on large-scale applications, I use Redux for state management. However, when it comes to building smaller applications and smaller personal projects, Redux can feel cumbersome. So, what’s the best light-weight solution for state management of these smaller applications? React hooks work really well for smaller applications, but sometimes you need to share state between components, and passing that state through components via props can get a little clunky. That’s where React Context comes to the rescue.

By utilizing the React Context API, you can avoid prop drilling. It also helps keep your components cleaner and simpler.

Let’s walk through what this would look like if we’re adding React Context to an application. First, I like to organize my context within a contexts folder within the src directory. Then I create a context file where all the global state will live. For this example, let’s call the file ItemContext.js:

import { createContext, useState } from "react";
import PropTypes from "prop-types";
const ItemContext = createContext();
const ItemProvider = ({ children }) => {
  const [items, setItems] = useState([]);
  const addItem = (item) => {
    const index = items[items.length - 1].id + 1;
    item.id = index;
    const updatedItems = [...items, item];
    setItems(updatedItems);
  };
  const editItem = (id, item) => {
    const index = items.findIndex((e) => e.id === id);
    const updatedItems = [...items];
    updatedItems[index] = item;
    setItems(updatedItems);
  };
  const removeItem = (id) => {
    const updatedItems = [...items];
    setItems(updatedItems.filter((item) => item.id !== id));
  };
  const context = {
    addItem,
    editItem,
    items,
    removeItem,
  };
  return <ItemContext.Provider value={context}>{children}</ItemContext.Provider>;
};
export { ItemContext, ItemProvider };
ItemProvider.propTypes = {
  children: PropTypes.object,
};

Next, within the src directory, if you don’t already have a hooks directory, create one where we’ll add a new hook file, useItemContext.js:

import { useContext } from "react";
import { ItemContext } from "../contexts/ItemContext";
const useItemContext = () => {
  return useContext(ItemContext);
};
export default useItemContext;

This file probably looks fairly small, but it will help us cut back on copying and pasting the same lines of code when we want to reference this global state. Now, when we want to access the global state or update the state via various components, we can do so by importing the context hook:

import useItemContext from "../hooks/useItemContext";
const ExampleComponent = () => {
  const { addItem, editItem, removeItem } = useItemContext();
  const handleAdd = (item) => {
    addItem(item);
  };
  const handleRemove = () => {
    removeItem(item.id);
  };
  const handleSave = (item) => {
    editItem(item.id, item);
  };
  return (
    {Add your presentation logic here}
  );
};
export default ExampleComponent;

October 16, 2022November 15, 2022

Lessons Learned from a Mass Tech Layoff

This year was the first time I was ever laid off from a company, and I figured I’d share my lessons learned from the experience. Maybe you’ll find them helpful if you ever find yourself in a similar situation or if you’re going through the same thing at the moment.

Lessons I learned from getting laid off from my Senior Software Engineering role:

Instead of diving into job hunting immediately, take some time to rest beforehand. I dove into job hunting immediately, although I was still feeling devastated from being laid off from a company that had been a dream job for me. I was processing my grief over losing a job while also feeling extremely exhausted from staying up late studying for technicals and waking up early for my scheduled interviews. This made it difficult to perform at my best during those interviews.
Don’t apply to too many places at once. Right after getting laid off, I panic-applied to a lot of companies. As a result, I had several companies responding to me at the same time to set up interviews. My calendar was crammed with interviews – recruiter calls, technicals, and take home assessments. I ended up feeling extremely overwhelmed and was spread too thin, and ultimately bombed too many interviews because I overextended myself. If I could go back and do things differently, I would have been more selective at the beginning of my job hunt. That way I wouldn’t have been so exhausted in the beginning.
Filter the unsolicited advice you’re getting from others and focus on what makes sense for you and your situation. I had a lot of friends/family give me their take on how I should approach the job hunting process. At first, I was trying to listen to too many people at once, and as a result, I was not only overwhelmed from everything that was going on in my life, but I was also overwhelmed from all the advice I was getting. What works for one person may not work for you, and that’s totally okay. Do what makes sense for you and makes the job hunting process manageable for you. For me, this meant cutting back on the interviews I was scheduling each week. I know that people mean well when they give you unsolicited advice, but no one truly knows what you’re going through better than you do, and ultimately you know better about what works for you.
Prioritize your mental health. Losing my source of income and my health insurance, processing the emotions from getting laid off, as well as dealing with the rejection that comes with the job hunting process, took a toll on my mental health. At first I was interviewing too much and not giving myself enough space to continue to pursue my hobbies or doing things that make me happy. Later, I realized I had to cut back on interviews so I could protect my happiness and mental health, and make time to do things that would bring me joy during this difficult time.
Have a strategic approach for the companies/roles that you apply to. At first, I didn’t have a strategy other than to apply to any role that fit my skill set at companies I was familiar with/really liked. Later, I realized the interview process was very important to me since I’m primarily self-taught, and live coding/whiteboarding interviews have always been tough for me. I ended up applying to companies that had tech screens that catered to my strengths while spending some of my free time working on LeetCode problems and studying CS so that I could move back to live coding/whiteboarding interviews in the future.
You can negotiate your severance. I had no idea you could negotiate your severance, so I just signed off on what was offered to me. If I could go back, I would have tried to negotiate, although the layoff my company did was one where there probably wasn’t much room for negotiation since so many people were laid off.
Listen to your gut. When you no longer have a job, it’s easy to feel desperate and feel like you should accept the first offer you get. If you’re financially able to hold off on doing that, I’d recommend waiting until you get an offer that excites you. I had a couple potential offers in the beginning of my search, but I wasn’t excited about them at all. And I think that’s definitely a red flag – you don’t want to start working for a company if off the bat you have some resentment about the offer.
Network and use social media to your advantage. I was able to get a lot of leads on possible job opportunities by reaching out to people who used to work at my previous companies. I was also getting a lot of help from strangers reaching out to me when I posted about getting laid off on LinkedIn.

Hopefully this is helpful for anyone else going through something similar. If you recently found a new job, congrats! If you’re still on the search for something new, good luck and hang in there!