如何在shell脚本的awk程序中使用$ xxx工作？

Question

查看以下unix shell脚本：

echo "Enter the pattern to be searched: \c"
read pname
echo "Enter the file to be used: \c"
reac flname
echo "Searching $pname from the file $flname."
grep "$pname" $flname
echo "The search results are displayed above."

请注意grep线。无论$ pname是否用花括号括起来，代码都能正常工作。现在我想尝试awk。

    echo "Enter the pattern to be searched: \c"
    read pname
    echo "Enter the file to be used: \c"
    reac flname
    echo "Searching $pname from the file $flname."
    awk 'BEGIN { FS = ":" } 
    $3 ~ /"$pname"/' $flname
    echo "The search results are displayed above."

现在的问题是：$ pname是否有围绕它的花括号，awk部分不起作用。为什么？有没有办法让awk部分工作？