Converting lowercase to uppercase in shell script

Question

I tried to convert a lowercase string to uppercase and assign it to a variable using the following code

The script is written in .tn extension

set y a12
y_up=$( tr '[A-Z]' '[a-z]' <<< $y)
echo $y
echo $y_up

But I am getting the error

invalid command name "A-Z"
while executing
"A-Z"
invoked from within
"y_up=$( tr '[A-Z]' '[a-z]' <<< $y) "

How can I convert this?

Answer 1

BASH 4+ version has native way to convert sting to upper case:

str="Some string here"
upperStr="${str^^}"