迴圈陣列

for 迴圈：

arr=(a b c d e f)
for i in "${arr[@]}";do
    echo "$i"
done

要麼

for ((i=0;i<${#arr[@]};i++));do
    echo "${arr[$i]}" 
done

while 迴圈：

i=0
while [ $i -lt ${#arr[@]} ];do
    echo "${arr[$i]}"
    i=$(expr $i + 1)
done

要麼

i=0
while (( $i < ${#arr[@]} ));do
    echo "${arr[$i]}"
    ((i++))
done