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Lambda Function with Amazon SNS

  Amazon SNS is a service used for push notification. In this chapter, we will explain working of AWS Lambda and Amazon SNS with the help of an example where will perform the following actions − Create Topic in SNS Service and use AWS Lambda Add Topics to CloudWatch Send SNS text message on phone number given. Requisites To create Topic in SNS Service and use AWS Lambda Add Topics to CloudWatch, we need not follow the steps given below − Create Topic in SNS Create Role for permission in IAM Create AWS Lambda Function Publish to topic to activate trigger Check the message details in CloudWatch service. To send SNS text message on phone number given, we need to do the following − Add code in AWS Lambda to send message to your phone. Example In this example, we will create a topic in SNS. When details are entered in the topic to publish, AWS Lambda is triggered. The topic details are logged in CloudWatch and a message is sent on phone by AWS Lambda. Here is a basic block diagram which exp
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Unix / Linux - Shell Input/Output Redirections

W e will discuss in detail about the Shell input/output redirections. Most Unix system commands take input from your terminal and send the resulting output back to your terminal. A command normally reads its input from the standard input, which happens to be your terminal by default. Similarly, a command normally writes its output to standard output, which is again your terminal by default. Output Redirection The output from a command normally intended for standard output can be easily diverted to a file instead. This capability is known as output redirection. If the notation > file is appended to any command that normally writes its output to standard output, the output of that command will be written to file instead of your terminal. Check the following  who  command which redirects the complete output of the command in the users file. $ who > users Notice that no output appears at the terminal. This is because the output has been redirected from the default standard output dev
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Unix / Linux - Shell Functions

W e will discuss in detail about the shell functions. Functions enable you to break down the overall functionality of a script into smaller, logical subsections, which can then be called upon to perform their individual tasks when needed. Using functions to perform repetitive tasks is an excellent way to create  code reuse . This is an important part of modern object-oriented programming principles. Shell functions are similar to subroutines, procedures, and functions in other programming languages. Creating Functions To declare a function, simply use the following syntax − function_name () { list of commands } The name of your function is  function_name , and that's what you will use to call it from elsewhere in your scripts. The function name must be followed by parentheses, followed by a list of commands enclosed within braces. Example Following example shows the use of function − #!/bin/sh # Define your function here Hello () { echo "Hello World" } # Invoke yo
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