For 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 are going to understand for loop in shell scripting.

The syntax for loop. There are many ways to write the for loop.

First way

  for <variable_name> in 1 2 3 4 5 . . N
  do
      command1
      command2
      command3
  done

Second way

  for <variable_name> in file1 file2 file3
  do
      command1 on $<variable_name>
      command2
      commandN
  done

Third way

  for <variable_name> in $(Linux-Or-Unix_Command_Here)
  do
      command1 on $<variable_name>
      command2 on $<variable_name>
      commandN
  done

Forth way

  for (( EXP1; EXP2; EXP3 ))
  do
      command1
      command2
      command3
  done

We can give the range to iterate like this {1..10}. Here the range is from 1 to 10
If we want to specify increment than we can do that in this way {1..10..2}. Here the range is from 1 to 10 and increment will be of 2
You can use the above methods only if your bash version is above 4.0. You can check you bash version by this command echo ${BASH_VERSION}

Reference code file for this article

So this was a brief introduction of for loop. 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.

For Loop | Shell Scripting

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