Git pre-commit hook to prevent non-ascii characters in C, C++, Erlang source code files

pre-commit

#!/bin/bash
#cp pre-commit .git/hooks/pre-commit
#chmod +x .git/hooks/pre-commit

filelist=`git diff HEAD --name-only --relative | grep -E '\.(c|h|cc|hh|cpp|erl|hrl|idl)$'`
abort='false'

for filename in $filelist
    do
        output=`git diff HEAD -- $filename | grep ^+[^+] | tr -d "\000-\011\013-\177" | tr -d '\n'`
        
        cnt=${#output}
        if [ -n "$output" ]; then
            if [ $abort == 'false' ]; then
                echo -e "\nAborting commit! Non ascii character(s) found in change set:\n"
            fi
            for ((i=0; i < cnt; i++))
                do
                    char=${output:$i:1}
                    echo -e "\nFound '$char' in file '$filename':\n"
                    git diff HEAD -S$char
                done
            abort='true'
        fi
    done

if [ $abort == 'true' ]; then
    echo -e "\nYou can skip pre-commit check with 'git commit --no-verify'"
    exit 1
fi

exit 0