Bash scripting - Decision Making

 

Decision Making

In programming, Decision Making is one of the important concepts. The programmer provides one or more conditions for the execution of a block of code. If the conditions are satisfied then those block of codes only gets executed.

Two types of decision-making statements are used within shell scripting. They are –

1. If-else statement:

If else statement is a conditional statement. It can be used to execute two different codes based on whether the given condition is satisfied or not.

There are a couple of varieties present within the if-else statement. They are –

  • if-fi 
  • if-else-fi 
  • if-elif-else-fi 
  • nested if-else

The syntax for the simplest one will be –

Syntax of If-else statement:

if [ expression ]; then

    statements

fi

Example Script:

Name="Satyajit"
if [ "$Name" = "Satyajit" ]; then
  echo "His name is Satyajit. It is true."
fi

Output of if-else statement:

His name is Satyajit. It is true.

In the above example, during the condition checking the name matches and the condition becomes true. Hence, the block of code present within the if block gets executed. In case the name doesn’t match then will not have an output. Below is the terminal shell pictorial depiction after executing the following script – 

 

2. case-sac statement:

case-sac is basically working the same as switch statement in programming. Sometimes if we have to check multiple conditions, then it may get complicated using if statements. At those moments we can use a case-sac statement. The syntax will be –

Syntax of case-sac statement:

case $var in
   Pattern 1) Statement 1;;
   Pattern n) Statement n;;
esac

Example Script:

Name="Satyajit"
case "$Name" in
    #case 1
    "Rajib") echo "Profession : Software Engineer" ;;
    
    #case 2
    "Vikas") echo "Profession : Web Developer" ;;
    
    #case 3
    "Satyajit") echo "Profession : Technical Content Writer" ;;
esac

Output of case-sac statement:

Profession : Technical Content Writer

In the above example, the case-sac statement executed the statement which is a part of the matched pattern here the ‘Name’. Below is the terminal shell pictorial depiction after executing the following script – 


Comments

Post a Comment

Popular posts from this blog

Terraform

Image
  Terraform is an infrastructure as code tool that lets you build, change, and version cloud and on-prem resources safely and efficiently. HashiCorp Terraform is an infrastructure as code tool that lets you define both cloud and on-prem resources in human-readable configuration files that you can version, reuse, and share. You can then use a consistent workflow to provision and manage all of your infrastructure throughout its lifecycle. Terraform can manage low-level components like compute, storage, and networking resources, as well as high-level components like DNS entries and SaaS features. How does Terraform work? Terraform creates and manages resources on cloud platforms and other services through their application programming interfaces (APIs). Providers enable Terraform to work with virtually any platform or service with an accessible API. HashiCorp and the Terraform community have already written  thousands of providers  to manage many different types of resources and services.
Read more

Scrum Master Interview help - Bootcamp

Understanding the MoSCoW prioritization | How to implement it into your project Projects, irrespective of their size or complexity, often juggle numerous tasks and requirements. In such a scenario,  MoSCoW prioritization  becomes essential to ensure the successful completion of the project.  Besides, it is also a very effective way to manage project priorities. With a straightforward and adaptable approach, the MoSCoW method helps manage stakeholder expectations and improve project outcomes. What is the MoSCoW prioritization technique?  The MoSCoW method is a prioritization matrix widely used in project management and software development. The term MoSCoW is an acronym that stands for  Must have ,  Should have ,  Could have , and  Won’t have , each denoting a level of priority. Here is the breakdown of the MoSCoW method:  Must have:  These are critical requirements that the project cannot be completed without them. If these are not fulfilled, the project is con
Read more

Kubernetes

  Using containers to host applications and other processes has gone mainstream. As more and more workload is moved into containers, management systems are needed to handle the demands of containerized applications at scale. One of the most popular options for managing  container-based workload is Kubernetes . Kubernetes combines container management automation with an extensible API to create a cloud-native application management powerhouse. At its core, Kubernetes manages the placement of pods, which can consist of one or more containers, on a Kubernetes cluster node. Additionally, if one of these pods crashes, Kubernetes can create a new instance of it. If a cluster node is removed, Kubernetes can move any affected workload to a different node in the cluster. On top of that, Kubernetes pods can be scaled to provide more or less throughput to meet scale demands and these scale operations can be triggered manually or automatically using Kuberentes horizontal pod auto-scaling. Finally,
Read more