How to Write a Script in K Shell

In the UNIX/Linux environment, there are many shell programs available. To run a Script in Unix you need shell programming to be installed in your Linux/Unix Os. Why I chose this topic is we are in the automation age and the automated things that run in the form of Script.

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The list of different shell programs

I have recently installed CentOs in my Vmware player and created Virtual machine. I installed light version of CentOs. In that, by default, only bourn shell available.

I want to install ‘Korn Shell’, so installed KSH using the below command. You can learn Linux scripting quickly without missing a single point here.

$ yum install  ksh

The below script I have created as a part of my learning.

$ vi myfirstscript.sh

Then, it goes to edit mode…Always better write your code only in small case letters. Since some interpreters, does not support Capital case letters.

The first symbol ‘#!’ indicates the location of your ‘ksh’ program. After entering into edit mode you need to press ‘Ins’, else, it will not allow you to edit.

The ‘;;’ indicates that end statement for each case.

The ‘*’ indicates that when other condition.

#My first menu script
#!/bin/ksh
echo " Enter Your Option Here:"

select menu_selections in Y N Q
do
  case $menu_selections in 
  Y) echo "Happy Birthday "
     ;;
  N) echo "Not Your Birthday "
     ;;
  Q) echo "Later tater "
     ;;
  *) echo "Invalid user"
     ;;
  esac
done
#End of script.

After entering the above pres ‘Esc’ and at the end give ‘:wq”. This means that quit and save.

$ ./myfirstscript.sh

Initially you will get an error, because you do not have execution permission. So, first you need to give permission. See more on file permissions.

$chmod 775 myfirstscript.sh

Then

$./myfirstscript.sh

The display comes as…

Enter Your Option Here:

1)Y
2)N
3)Q
#?

So, just give 1, 2, or 3 and any other number and verify the result. This is the first script I practiced. So I am sharing it with you.