Bash print the number of incorrect file line - bash

Question

A beginner asking for help (:
So, I have a script that checks brackets in a text file and tells whether they are closed correctly. However, I also want to make my script print out the number of the incorrect line (where brackets are closed incorrectly). I have tried counting file lines and then making a nested while loop, however, it doesn't work for me at all ): Are there any simple solutions for this? I would like to leave the LINE counter if that's possible o:
INPUT="$1"
count=0
LINE=0
# Check if file exists
[ ! -f $INPUT ] && { echo "file $INPUT do not exist."; exit ; }
# Count file lines and read every char
while IFS= read -r LINE
do
LINE=$(( LINE + 1 ))
while read -n1 char
do
[ "$char" == "(" ] && (( count++ ))
[ "$char" == ")" ] && (( count-- ))
if [ "$count" -lt 0 ]
then
break
fi
done
done < "$INPUT"
if [ "$count" -lt 0 ]
then
echo "Found a mistake in $LINE line "
else
echo "Everything's correct"
fi

Answer 1

You have a couple of problems:
Your read in the inner loop consumes the input from the file, not from LINE.
The line
LINE=$(( LINE + 1 ))
is really wrong: LINE is the content of the line of your file, and your trying to add 1 to it. Weird.
Your break only breaks the inner loop (it should break two loops). Use break 2 for this.
Here's a working version of your script:
input=$1
count=0
linenb=0
# Check if file exists
[[ -f $input ]] || { echo "Error: file $input do not exist."; exit 1; }
# Count file lines and read every char
while IFS= read -r line; do
((++linenb))
while read -n1 char; do
[[ $char == '(' ]] && ((++count))
[[ $char == ')' ]] && ((--count))
((count>=0)) || break 2
done <<< "$line"
done < "$input"
if ((count<0)); then
echo "Found a mistake in line #$linenb:"
printf '%s\n' "$line"
else
echo "Everything's correct"
fi
Note that I used more ((...)) and [[...]].
I also used lowercase variable names, as your computer isn't deaf: you don't need to shout the name of the variable. (And it's nicer to the eye). And it's good practice to use lowercase variable names, as there's no chance that they clash with Bash's own variables.