Read File's Content using While Loop | Shell Scripting

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This is a multipart blog article series where I am going to explain the concepts of shell scripting and how to write a shell script in Linux, UNIX or Mac based systems. You can also follow this tutorial blog using windows but for that you have to install a bash from.

In this article we will see various ways by which we can read the content of a file using while loop and shell script.

  1. The first method is like this.
    • Here we use < input redirection.
    • This means that the content of the file will be sent to the while loop and then we will store the value of while loop inside a variable and then print the content of that variable line by line.
    • while read <variable_name>
      do
        echo $<variable_name>
      done < <file_name>
      
  2. Second way is like this.
    • Here the output of the cat command is the input of the while command.
    • cat <file_name> | while read <variable_name>
      do
        echo $<variable_name>
      done
      
  3. The third way to do the same thing is like this.
    • We cannot use the above methods in some cases, than we use the IFS methods.
    • Here we are assigning space to IFS.
    • We use -r because with the help of this it will do not interpret backslash.
    • while IFS='' read -r <variable_name>
      do
        echo $<variable_name>
      done < <file_name>
      
  4. At the place of file we can also give the file present at different location, along with their address just like this /etc/someFile.txt

Refernece code for this article

So this was all about the different ways by which we can read the content of the file using while loop in a shell script. Hope you liked it and learned something new form it.

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