DEV Community: Michael Briseno

./What_is_BASH?!.sh

Michael Briseno — Mon, 28 Aug 2023 10:41:49 +0000

Tired of doing boring, repetitive tasks? BASH scripting is a powerful way to automate those tasks and manipulate data on Linux systems. BASH stands for Bourne Again Shell (no relation to Jason Bourne), which is a command-line interpreter that can execute commands from a file or interactively from the terminal.

What is a BASH script?

A BASH script is simply a file that holds a bunch of Linux commands and when you run the script it will run the commands in order from top to bottom. A bash script can also use variables, functions, loops, conditional statements, and other features to create more complex and dynamic scripts.

To create a BASH script, you need to follow these steps:

Create a file, you can use the extension .sh but it is not necessary. Use any text editor to write your script. For example, you can use nano, or vim.
Start your script with a SHEBANG line, which tells the system what scripting language will be used to run the script. The shebang line is usually #!/bin/bash for BASH scripts.

Fill your file with commands in the order you want them executed.
To be able to run your script you must make your script executable by using the chmod command. For example, chmod +x my_script.sh. (you can also type "bash my_script.sh" to run it without getting executable permission)
Run your script by typing its name or its full path in the terminal. For example, ./my_script.sh or /home/user/my_script.sh. Depending where you are in your directory.

Conclusion

Bash scripting is a useful skill that can help you automate tasks and manipulate data on Linux systems. Thanks for stopping by to read and learn some basics of BASH, check out the resources below to learn more about BASH!

RESOURCES

Here are some great YouTube personalities/ resources to try to learn more BASH from.

NETWORK CHUCK BASH SERIES - great place to start
Shawn Powers BASH series - easy to follow examples
Devhints.io BASH Cheat Sheet
Learn Linux TV Bash Series - Longer series than others, covers a lot with examples covering backingup and scheduling jobs
Scott Simpson Linkedin Learning BASH scripting Course - MUST HAVE Linkedin Premium - Provides Git Repo that you can fork and use Gits Codespaces to follow along!
Microsoft Developer Bash for Beginners
- Great course to start off with, also provides a Git Repo taught by @madebygps @joshduffney

25 Essential Linux Commands (CLI)

Michael Briseno — Tue, 08 Aug 2023 15:11:55 +0000

25 Essential Linux Commands

Linux is a powerful operating system that is widely used in the world of computing. It is used in 83.6% of all technology (fake stat). It is known for its stability, security, and flexibility. In this article, we will discuss some of the essential Linux commands that every user should know.

Note: that these commands can also be more specified with the use of options. Just use "man" followed by any of the commands, this will send you to the manual page for that command with all the available options you can use.

1. whoami

The whoami command is used to display the username of the current user. This command is useful when you need to know which user you are logged in as.

Example:

whoami

Output:

user

2. pwd

The pwd command is used to "Print Working Directory", it will display the current working directory. This command is useful when you need to know which directory you are currently in.

Example:

pwd

Output:

/home/user

3. ls

The ls command is used to "list" the files and directories in the current working directory. This command is useful when you need to know what files and directories are in a directory.

Example:

ls

Output:

file1.txt file2.txt dir1 dir2

4. cd

The cd command is used to "change directory", will change the current directory. This command is useful when you need to navigate to a different directory.

Example:

cd /home/user/Documents

CHEAT CODE:

cd ..

will bring you back one directory, to the parent directory.

5. touch

The touch command is used to create an empty file. This command is useful when you need to create a new file.

Example:

touch file.txt

6. mkdir

The mkdir command is used to "make" a new directory. This command is useful when you need to create a new directory.

Example:

mkdir newdir

7. rm

The rm command is used to "remove" files and directories. This command is useful when you need to delete files or directories.

Example:

rm file.txt
rm -r dir1

8. cp

The cp command is used to "copy" files and directories. This command is useful when you need to make a copy of a file or directory.

Example:

cp file.txt newfile.txt
cp -r dir1 newdir1

9. mv

The mv command is used to "move" files and directories. This command is useful when you need to move a file or directory.

Example:

mv file.txt /home/user/Documents/
mv dir1 /home/user/Documents/

10. tar

The tar command is used to create and extract tar archives. This command is useful when you need to compress or decompress files.

Example:

tar -cvf archive.tar file1.txt file2.txt dir1 dir2
tar -xvf archive.tar

11. Gzip

The gzip command is used to compress files. This command is useful when you need to compress large files.

Example:

gzip file.txt 
gunzip file.txt.gz

12. Zip

The zip command is used to create and extract zip archives. This command is useful when you need to compress or decompress files.

Example:

zip archive.zip file1.txt file2.txt dir1 dir2 
unzip archive.zip

13. Cat

The cat command is used to display the contents(conCATenation) of a file. This command is useful when you need to view the contents of a file.

Example:

cat file.txt

14. tac

The tac command is used to display the contents of a file in reverse order, think of CAT but backwards. This command is useful when you need to view the contents of a file in reverse order.

Example:

cat file.txt

15. nano

The nano command is used as a text editor for creating and editing text files. This command is useful when you need to edit text files.

Example:

nano file.txt

16. vi

The vi command is also used as a text editor for creating and editing text files. This command is useful when you need more advanced editing capabilities than nano provides.

Example:

vi file.txt

17. vim

The vim command is an "improved" version of vi with more advanced features for creating and editing text files.

Example:

vim file.txt

18. sed

The sed command is used for Stream EDiting of text
files. This command can be used for search and replace operations on text files.

Example:

sed 's/old/new/g' file.txt

19. awk

The awk command is used for processing text files. It can be used for searching, filtering, and manipulating text data.

Example:

awk '/pattern/ { print $0 }' filename

20. grep

The grep command searches for lines that match a pattern in one or more files. Stands for Global search / Regular Expressions / Print.

Example:

grep 'pattern' file.txt

21. chmod

The chmod command is used to change the permissions of a file or directory("Change mode"). This command is useful when you need to change the permissions of a file or directory.

Example:

chmod 755 file.txt

22. chgrp

The chgrp command is used to change the group ownership of a file or directory. This command is useful when you need to change the group ownership of a file or directory.

Example:

chgrp users file.txt

23-25. Usermod, useradd, groupadd

The usermod, useradd, and groupadd commands are used for user and group management. These commands are useful when you need to add, modify, or delete users and groups.

Example:

useradd -m -s /bin/bash username
usermod -aG groupname username
groupadd groupname

As I work on learning linux and earn a certificate in Linux(LFCS) I have found these are the most recurring commands that I have used. I hope this article helps you get started with some of the essential Linux commands!

Learn AWS RDS Now!

Michael Briseno — Fri, 19 May 2023 10:38:15 +0000

I "recently" finished Andrew Browns 'Week 4' of his AWS Bootcamp! In this bootcamp we were creating a Twitter clone website, utilizing AWS. The topic for the week was... You guessed it, RDS! I wont be going over how to do all of these, but I will go over some good takeaways I learned from my mistakes. Spoiler alert: it was a lot of human errors.

I learned how to:

Provision an RDS instance via CLI!
Create a Postgres DB using CLI shortcuts
Troubleshoot
Learned to write and use BASH scripts ( SHEBANG )
Did I say Troubleshoot yet? Because I did a lot of that.
Implement a Lambda that runs in a VPC and commits code to RDS
Programmatically update a security group rule
Operate common SQL commands
Create AWS Cognito trigger to insert user into database (Headache!)

"Yeah, yeah, cool you learned a lot, but what is RDS? and why should I care?!"
-you, the reader.

What is RDS?

A web service (Relational Database Service) that makes it easier to set up, operate, and scale a relational database in the AWS Cloud. It provides cost-efficient, resizable capacity for an industry-standard relational database and manages common database administration tasks.

Here are some examples of how companies use AWS RDS.

Expedia uses AWS CloudFormation with Chef to deploy its entire front and backend stack into its Amazon Virtual Private Cloud (Amazon VPC) environment. Expedia Group uses a multi-region, multi-availability zone architecture with a proprietary DNS service to add resiliency to the applications.
Unilever used AWS Service Catalog to scale its database-as-a-service platform, facilitating simple database deployments, management, and support with a lean team of engineers.

Some benefits of using AWS RDS for companies like Unilever and Expedia include:

Scalability: RDS allows companies to easily scale their databases up or down as needed with simple API calls or a few manual changes from the AWS Management Console.
Reduced Database Administration: RDS handles routine database management tasks such as provisioning, backup, recovery, repair, patching, and failure detection. This frees up time for developers to innovate for their customers.
Cost Savings: Companies only pay for the resources they use with RDS, without up-front investments.
Increased Agility and Resiliency: By using AWS, Expedia Group has become more resilient and its developers have been able to innovate faster while saving the company millions of dollars.

Troubleshooting Issues:

We all encounter issues in all of our jobs or tools we use. Whether you are a pro or a beginner (N00b) we all have done something dumb to sometimes be the cause of said issue. The important thing is to remember it and learn from it!

Here are just a couple of the things I learned.

Ran into lots of issues with the Postgres table not pushing to the website backend. I later found through the very helpful discord that someone else had the same connection pool error that I had, however, my issue was simply I had forgotten to re-compose up my docker image after making changes to the docker compose file. Do not forget to double-check the "little things"!
I recently came to the realization that I had forgotten to turn the instance back 'on' after creating a new database named "2". It was a simple oversight on my part, but I will make sure to be more mindful moving forward.
Next issue: syntax, a simple extra word can screw up your code and thus I spent 20+ minutes trying to figure that out...
Last issue: In AWS lambda our lambda had an environment variable for my 'CONNECTION_URL' that was not fully correct. Checking docker logs and Cloudwatch logs to find the issue it ended up being that I had some syntax error, always double-check your Environment variables! In my code it is 'CONNECTION_URL = PROD_CONNECTION_URL = "XXX" '. However, in the AWS console Lambda portion, it doesn't need the
" = PROD_CONNECTION_URL" portion, just the value afterwards! After I cleared that up, the user I created (via AWS Cognito) was able to connect with the Postgres table and fill it in with user info! ( had some help from the boot camp Discord - someone else had the same problem, I tried to fix it myself at first but alas I went looking for help - do not deny yourself help when you need it)

Although this "week" took me more than a week( LOL), I managed to finish it, and although I won't be finishing the boot camp I will continue with my fundamental cloud studies(Linux, Networking, AWS). I have learned so much in the "5 weeks" of instruction that was provided by Andrew Browns AWS bootcamp!

Sorry for the long post! Thanks for reading!! Follow for more cloud/tech-related content! Please comment to let everyone know how you use RDS if you do!

AWS E-SEA-TWO?

Michael Briseno — Sat, 08 Apr 2023 02:11:27 +0000

I have been learning about AWS services and one of the key services to AWS is the EC2 instance! But you cannot learn EC2 without knowing about its other important friends EBS and EFS!

What is AWS EC2?

Have you ever wanted to use a computer that’s not in your house? Maybe you’re on vacation and need to do some work, or maybe you want to play a game with your friends but your computer isn’t fast enough. That’s where AWS EC2 can comes in!

AWS EC2 (Amazon Web Services Elastic Compute Cloud) is a service that lets you rent computers in the cloud. It’s like renting a computer that you can access from anywhere in the world. You can use it to run your programs, play games or do anything else you would do on a regular computer. ( The “elastic” part of the name refers to the ability to easily scale up or down the number of virtual computers you’re using based on your needs )

Its like renting a movie from Blockbuster back in the day, but instead of renting a movie you're renting a computer. It can get turned on pretty quickly and ready to use within minutes!

What is AWS EBS?

When you rent a computer with AWS EC2, you might want to save some files on it. Maybe you’re working on a project and need to save your work, or maybe you want to download some music to listen to later. That’s where AWS EBS comes in!

AWS EBS (Elastic Block Store) is a service that provides storage for your EC2 instances. It’s like a hard drive that you can attach to your rented computer to store your files. You can choose how much storage you need and only pay for what you use.

Another thing to consider is if your rented computer goes down for any reason, then you still have your storage separate from the EC2 instance computer. So it's as easy as setting up a new one and attaching this storage to the new one and you're good to go! - This decoupled way of managing these services is what makes AWS/cloud powerful!

What is AWS EFS?

Sometimes, you might want to share files between multiple EC2 instances. Maybe you’re working on a group project and need to share your work with your teammates, or maybe you want to play a game with your friends and need to share the game files. That’s where AWS EFS comes in!

AWS EFS (Elastic File System) is another storage service that lets you share files between multiple EC2 instances. It’s like having a shared folder that all your rented computers can access. You can use it to store and share files with others easily.

The following video is a good rundown of EC2! Its a bit of a tutorial but with explanations throughout the walkthrough!
https://www.youtube.com/watch?v=V2eh-m5naOY

Thanks for reading and follow for more Cloud and Linux articles!

What the grep?!

Michael Briseno — Sat, 25 Mar 2023 13:51:55 +0000

How to Master the grep Command in Linux

If you are a Linux user, you probably know how powerful and versatile the command line can be. You can perform various tasks with just a few keystrokes, such as searching for files, manipulating text, processing data, and more.

One of the most useful and popular commands in Linux is grep, which stands for global regular expression print. Grep allows you to search for a pattern of characters in a file or a stream of input and print the matching lines. You can also use grep to filter out unwanted lines, count occurrences of a pattern, highlight matches, and more! Super helpful!

In this article, I will show you some common uses of grep and explain how it works. I will also list 5 reasons why you should learn and use grep when using Linux.

What is grep? History of grep

Grep was originally developed by Ken Thompson in 1973 as part of the Unix operating system. The name comes from a command in the ed text editor that performed a similar function: g/re/p (global/regular expression/print).

A regular expression (or regex) is a sequence of characters that defines a search pattern. For example, if you want to find all lines that contain the word "hello", you can use the regex "hello". If you want to find all lines that start with "a" and end with "z", you can use the regex "^a.*z$".

Grep uses regular expressions to match patterns in files or input streams. It then prints the matching lines to standard output (or stdout), which is usually your terminal screen. You can also redirect stdout to another file or command using pipes (|) or redirection operators (>).

Here is a great video from Computerphile on grep!

Link

How to use grep?

The basic syntax of grep is:

grep [options] pattern [file...]

The options are optional flags that modify the behavior of grep. For example, -i makes grep ignore case differences, -v makes grep invert the match (print non-matching lines), -c makes grep count matching lines instead of printing them, etc.

The pattern is the regular expression that defines what you are looking for. You can enclose it in single or double quotes if it contains spaces or special characters.

The file argument(s) specify which file(s) to search. If no file is given, grep reads from standard input (or stdin), which is usually your keyboard input or another command's output.

Here are some examples of using grep:

To find all lines that contain "linux" in a file called "example.txt":

grep linux example.txt

To find all lines that start with "#" (comments) in multiple files:

grep ^# *.txt

To find all files in the current directory that contain "error" (case-insensitive):

grep -i error *

To find all processes that are running as root:

ps aux | grep root

Why should you learn and use grep?

Here are 5 reasons why learning and using grep can make your life easier when working with Linux:

Grep is fast and efficient. It can scan large files or streams quickly and display only relevant information.
Grep is flexible and powerful. It supports various options and regular expressions that allow you to fine-tune your search criteria and perform complex tasks.
Grep is ubiquitous and portable. It comes pre-installed on every Linux distribution²⁴⁶and works on any text-based file or input.
Grep is easy to learn and use. It has a simple syntax and intuitive logic that make it easy to master.
Grep is fun and rewarding. It can help you discover new things, solve problems, automate tasks, and more.

Conclusion

Grep is one of the most useful commands in Linux that every user should know how to use effectively. It allows you to search for patterns in files or input streams using regular expressions and print matching lines.

I hope this article helped you understand what grep is and how to use it better.

Want To Learn Linux? Start Here.

Michael Briseno — Thu, 02 Mar 2023 10:49:42 +0000

TL;DR: Great resource to learn Linux for Beginners for free at r/linuxupskillchallenge

But What is Linux?

Linux is a powerful and versatile operating system that powers most of the servers on the internet. If you want to learn how to use Linux for your personal or professional projects, you might be overwhelmed by the amount of information and resources available online.

So which resource do I start with?

That’s why I recommend you check out r/linuxupskillchallenge, a subreddit that offers a month-long(20 days) course on Linux server administration. The course is aimed at beginners who aspire to learn about Linux and get their feet wet, also lightly geared towards those that want to get Linux-related jobs in the industry, such as junior Linux sysadmin (Please don't expect to get hired after this course).

Understand this course shouldn't be your only learning resource. On the contrary, the course encourages the student to go further into the daily topics covered in their free time.

How Does This Course Work?

The course is not a formal one, nor does it give you a certificate to share on social media. Instead, it gives you practical and hands-on experience with Linux commands, tools, and concepts that you can apply to real-world scenarios. This has been by far the best way to learn Linux for me. Getting hands-on in the command line and typing things. Getting errors or not the "right" response to an action and figuring out why has been very helpful in solidifying the concepts.

The course consists of 20-day lessons(starting every first Monday of the month) that are posted as sticky threads on the subreddit every weekday of the month. Each lesson covers a different topic, such as installing Linux, managing users and groups, working with files and directories, configuring network services, securing your server, and more. Most of the day lessons are accompanied by a video that helps get you started.

You can follow along at your own pace and ask questions or share your feedback on the subreddit. Livia Lima has been running this subreddit and is a great steward for the Linux community and the subreddit. She is active on the subreddit, so if you do run into a question or issue, you can reach out and expect a prompt answer! You can also find additional resources and tips on the official website of the course or on GitHub.
Github:

livialima / linuxupskillchallenge

Learn the skills required to sysadmin a remote Linux server from the commandline.

Linux Upskill Challenge

An Introduction to Linux Server Administration

The Linux Upskill Challenge is free and open source — and it always will be.

All core learning materials are accessible year-round. No subscriptions, no registration required - so costs you nothing but your time!

If you spot any typos or "dead links" simply raise an issue.

READ THIS FIRST!

HOW THIS WORKS & FAQ

Day 0 - Creating Your Own Server: how to setup your lab in AWS, Azure, Google Cloud, Digital Ocean and on a local server
Day 1 - Get to know your server: Starting with ssh-ing in and some simple commands like: ls, uptime, free, df -h, uname -a. Extensions on doing passwordless login…

View on GitHub

But How Much is it?

The best part is that the course is completely free and open-source. You only need a computer with internet access and a willingness to learn. ( and setting up a Linux Machine -free ways described in the subreddit)

You don’t need any prior knowledge of Linux or programming. There is a setup guide in the subreddit(day-0) if you would like to use the cloud to host your Linux machine, if not, then there are many other ways to have your own Linux machine to practice on. (local VM, or web-based sandboxes)

If you are interested in joining this challenge, you can sign up for the next course that starts on Monday 6 March 2023. If you are reading this in from the future, do not worry, this challenge restarts every month starting every first Monday of the month! All you have to do is subscribe to r/linuxupskillchallenge and wait for the first lesson to be posted.

I hope this article has sparked your curiosity about Linux and motivated you to take on this challenge. Learning Linux can be fun and rewarding if you have a clear goal and a supportive community. So what are you waiting for? Join r/linuxupskillchallenge today!
https://www.reddit.com/r/linuxupskillchallenge

DEV Community: Michael Briseno

./What_is_BASH?!.sh

What is a BASH script?

Conclusion

RESOURCES

25 Essential Linux Commands (CLI)

25 Essential Linux Commands

1. whoami

2. pwd

3. ls

4. cd

5. touch

6. mkdir

7. rm

8. cp

9. mv

10. tar

11. Gzip

12. Zip

13. Cat

14. tac

15. nano

16. vi

17. vim

18. sed

19. awk

20. grep

21. chmod

22. chgrp

23-25. Usermod, useradd, groupadd

Learn AWS RDS Now!

I learned how to:

What is RDS?

Troubleshooting Issues:

AWS E-SEA-TWO?

What is AWS EC2?

What is AWS EBS?

What is AWS EFS?

What the grep?!

How to Master the grep Command in Linux

What is grep? History of grep

How to use grep?

Why should you learn and use grep?

Conclusion

Want To Learn Linux? Start Here.

But What is Linux?

So which resource do I start with?

How Does This Course Work?

livialima / linuxupskillchallenge

Learn the skills required to sysadmin a remote Linux server from the commandline.

Linux Upskill Challenge

An Introduction to Linux Server Administration

READ THIS FIRST!

Table of Contents

But How Much is it?