bash设置了双等号==

Question

在bash脚本中的集合调用中，双等号==是什么意思？ 以下是摘自INDIRECT function的示例：

for arg in "$@"; do
    shift
    case "$arg" in
        "--help") set -- "$@" "-h" ;;
        "--feature") set -- "$@" "-f" ;;
        "--log-path") set -- "$@" "-p" ;;
        "--shell") set == "$@" "-s";;
        "--scenarios") set == "$@" "-S";;
        "--ssh-key") set == "$@" "-k";;
        "--ssh-public-key") set == "$@" "-K";;
        "--background") set == "$@" "-b";;
        "--no-color") set == "$@" "-n";;
        "--all") set == "$@" "-a" ;;
        "--params-file") set == "$@" "-P" ;;
        "--use-ci-image") set == "$@" "-i" ;;
        *) set -- "$@" "$arg"
    esac
done