Bash script set help function

set -o nounset

help()
{
    cat <<- EOF
    Desc: execute f1x for each case in Codeflaws
    Usage: ./exec_codeflaws.sh [Codeflaw_dir] [f1x_path] [run-f1x-codeflaw.rb_Dir]
    EOF
    exit 0
}

while [ -n "$1" ]; do
    case $1 in
        -h) help;;
        --) shift;break;;
        -*) echo "error: no such option $1."; exit 1;;
        *) break;;
esac
done

Referred from: https://blog.csdn.net/hejinjing_tom_com/article/details/79946427