Search for exact string - bash

Question

I'm trying to search for exact string located in chars number 4-7.
When I run the cut command on terminal it works,
however in a script it fails as I believe the if statement provide me "0".
This is what I've done:
for NAME in `cat LISTS_NAME`; do
if [[ John == cut -c 4-7 "${NAME}" ]]; then
Do Something ...
fi
if [[ Dana == cut -c 4-7 "${NAME}" ]]; then
Do Something...
fi
Can you advise me how to run this using cut or any other reg-ex?

Answer 1

You aren't running the cut command there. You are comparing John and Dana to the literal string cut -c 4-7 <value-of-$NAME>.
You need to use:
if [[ John == $(cut -c 4-7 "${NAME}") ]]; then
etc.
That being said you should only do the cut call once and store that in a variable. And for exact matching you need to quote the right-hand side of == to avoid globbing. So
substr=$(cut -c 4-7 "${NAME}")
if [[ John == "$substr" ]]; then
And then to avoid needing duplicate if ...; then lines you could do better with a case statement:
substr=$(cut -c 4-7 "${NAME}")
case $substr in
John)
Do something
;;
Dana)
Do something else
;;
esac

Answer 2

Your script has many problems and you don't need cut. Use it this way:
while read -r line; do
if [[ "${line:3:4}" == "John" ]]; then
Do Something ...
elif [[ "${line:3:4}" == "Dana" ]]; then
Do Something...
fi
done < LISTS_NAME
In BASH "${line:3:3}" is same as cut -c 4-7
EDIT: If you don't want precise string matching then you can use:
while read -r line; do
if [[ "${line:3}" == "John"* ]]; then
Do Something ...
elif [[ "${line:3}" == "Dana"* ]]; then
Do Something...
fi
done < LISTS_NAME