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Rahul Mishra
Rahul Mishra

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Read File's Content using While Loop | Shell Scripting

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. - shell 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. - shell 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. - shell 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

Reference 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.

If you have any doubt, question, quires related to this topic or just want to share something with me, than please feel free to contact me.

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