Pass prompt option to a file

I want to create a script where I have pre-defined option values. opt1 opt2 opt3

I will start a script and it will ask me to choose from opt1 - opt3. Once I pick e.g. opt2, that opt2 will then be passed as a variable.

How can I please achieve it?

Solution

You can use the "case" command to check if the user value is on a list of expected values:

#!/bin/bash

selected_option=""

echo " *** MENU ***"
echo "1) Opt1"
echo "2) Opt2"
echo "3) Opt3"
echo -n " Please, enter your option: "
read user_answer

case $user_answer in
  1|2|3) selected_option="$user_answer"
         ;;
  *) echo "Invalid Option!"
esac

##### Show the result only if the user selected an valid option #####
if [[ ! -z "${selected_option}" ]]; then
  echo "Selected Option: [${selected_option}]"
fi

The '|' can be used to separate the valid options, and it will act as an "or" operator.

The '*' section will be executed if the previous condition is not satisfied, which means a "default" behavior, at this case it will display "Invalid Option" message.

Finally, the last if checks if the variable "${selected_option}" is empty, if not it is printed, but you can do whatever you want with that.