Cloud computing has revolutionized the way businesses and individuals use technology. It provides on-demand access to computing resources—servers, storage, databases, networking, software, analytics, and intelligence—over the internet ("the cloud") without requiring users to manage the underlying infrastructure. Understanding the fundamental concepts of cloud computing is crucial for anyone pursuing the AWS Cloud Practitioner certification, as it forms the basis for understanding AWS services and how they solve real-world problems. This lesson will explore these core concepts, setting the stage for a deeper dive into AWS-specific services and solutions in subsequent modules.

#!/bin/bash
# Assign a value to a variable
name="World"
echo "Hello, $name!"

Cloud computing is the on-demand delivery of compute power, database storage, applications, and other IT resources through a cloud services platform via the internet with pay-as-you-go pricing. Instead of owning and maintaining physical data centers and servers, organizations can access these resources from a cloud provider.

• On-Demand Self-Service: Users can provision computing resources, such as servers and storage, as needed without requiring human interaction with the service provider.
  • Example: A developer can spin up a new virtual server in minutes through a web interface or API, without needing to call a system administrator.
  • Example: A marketing team can increase their email marketing platform's capacity during a campaign launch, scaling down afterward to save costs.
• Broad Network Access: Cloud capabilities are available over the network and can be accessed from a wide range of devices, such as laptops, tablets, and smartphones.
  • Example: Employees can access company applications and data from anywhere with an internet connection, enabling remote work.
  • Example: Customers can access a web application hosted in the cloud from any device with a web browser.
• Resource Pooling: The provider's computing resources are pooled to serve multiple consumers using a multi-tenant model, with different physical and virtual resources dynamically assigned and reassigned according to consumer demand.
  • Example: A cloud provider might have a large pool of servers that are shared among multiple customers. Each customer gets a virtual server that runs on one of these physical servers.
  • Example: Storage resources are dynamically allocated to users based on their needs, without them needing to know the physical location of the data.
• Rapid Elasticity: Resources can be elastically provisioned and released, in some cases automatically, to scale rapidly outward and inward commensurate with demand. To the consumer, the capabilities available often appear unlimited and can be appropriated in any quantity at any time.
  • Example: An e-commerce website can automatically scale up its server capacity during a flash sale to handle increased traffic and then scale down afterward to reduce costs.
  • Example: A data analytics application can automatically provision more computing resources to process a large dataset and then release those resources when the processing is complete.
• Measured Service: Cloud systems automatically control and optimize resource use by leveraging a metering capability at some level of abstraction appropriate to the type of service (e.g., storage, processing, bandwidth, and active user accounts). Resource usage can be monitored, controlled, and reported, providing transparency for both the provider and consumer of the utilized service.
  • Example: Users are charged based on the amount of storage they use, the number of compute hours they consume, or the amount of data they transfer.
  • Example: A company can track its cloud spending in real-time and identify areas where it can optimize costs.

#!/bin/bash
# Counting the number of lines in a list of files
# for loop over arguments

if [ $# -lt 1 ]
then
  echo "Usage: $0 file ..."
  exit 1
fi

echo "$0 counts the lines of code" 
l=0
n=0
s=0
for f in $*
do
	l=`wc -l $f | sed 's/^\([0-9]*\).*$/\1/'`
	echo "$f: $l"
        n=$[ $n + 1 ]
        s=$[ $s + $l ]
done

echo "$n files in total, with $s lines in total"

Cloud computing can be deployed in different models, each offering varying levels of control, flexibility, and management responsibility. The three primary cloud deployment models are:

Public Cloud

The public cloud is owned and operated by a third-party cloud service provider, which delivers computing resources over the internet. These resources are available to anyone who wants to use them. AWS is a public cloud provider.

• Characteristics:
  • Owned and operated by a third-party provider.
  • Resources are shared among multiple tenants.
  • Highly scalable and elastic.
  • Pay-as-you-go pricing.
  • Lower cost compared to other models.
• Examples: AWS, Microsoft Azure, Google Cloud Platform.
• Use Cases: Web applications, software testing and development, data storage, and backup.
• Hypothetical Scenario: A startup company needs to quickly launch a new web application. They choose a public cloud provider to avoid the upfront costs and complexity of building their own infrastructure.

The private cloud is infrastructure used exclusively by a single organization. It can be located on-premises or hosted by a third-party provider.

• Characteristics:
• Infrastructure is dedicated to a single organization.
• Greater control over security and compliance.
• Can be more expensive than public cloud.
• Requires more management effort.
• Examples: VMware, OpenStack.
• Use Cases: Sensitive data storage, regulatory compliance, mission-critical applications.
• Hypothetical Scenario: A financial institution needs to store and process highly sensitive customer data. They choose a private cloud to maintain strict control over security and compliance.