shell腳本if判斷時報[: missing ]

源代碼：

if [ -d "test"]
then
        echo dir named test exsited!
elif [ ! -d "test"];then
        mkdir test
        cd test
fi      

[: missing ]      

if [ -d "test" ]
then
        echo dir named test exsited!
elif [ ! -d "test" ];then
        mkdir test
        cd test
fi