if [ -r "$FILE" ]; then ----- ③
    echo "-r operator: True"
else
    echo "-r operator: False"
fi

if [ -d "$FILE" ]; then ----- ④
    echo "-d operator: True"
else
    echo "-d operator: False"
fi

if [ -s "$FILE" ]; then ----- ⑤
    echo "-s operator: True"
else
    echo "-s operator: False"
fi

FILE="/etc/passwd"  --------- ⑥
echo "target file is $FILE"