normalize a string in bash to uppercase with underscores examples

gistfile1.txt

#!/bin/bash

## Convert 'this/is a:string 123' to THIS_IS_A_STRING_123
##

# converting a hard coded string to all uppercase with underscoree
echo "this/is a:string 123"  | iconv -t ascii//TRANSLIT | sed -r s/[^a-zA-Z0-9]+/_/g | sed -r s/^-+\|-+$//g | tr a-z A-Z
# output: THIS_IS_A_STRING_123

# using variables variable
STRING='this/is a:string 123'
STRING2=$(echo $STRING | iconv -t ascii//TRANSLIT | sed -r s/[^a-zA-Z0-9]+/_/g | sed -r s/^-+\|-+$//g | tr a-z A-Z)
echo $STRING2;
# output: THIS_IS_A_STRING_123

# with a function
uppify () {
 echo $(echo $1 | iconv -t ascii//TRANSLIT | sed -r s/[^a-zA-Z0-9]+/_/g | sed -r s/^-+\|-+$//g | tr a-z A-Z)
}
STRING='this/is a:string 123'
uppify "$STRING";
# output: THIS_IS_A_STRING_123

RESULT=$(uppify "$STRING")
echo result is $RESULT
# output: resul is THIS_IS_A_STRING_123