shell中引号的妙用

#!/bin/bash
file=('leon 01.cap' leon-02.cap nicky-01.cap whoareu-01.cap 8dbb-01.cap)
dict=(simple.txt password.txt bir.txt)

for i in "${file[@]}"
do
    for j in "${dict[@]}"
    do
        echo "aircrack-ng '${i}' -w dict/${j}"
    done
done