shell，sed修改指定位置的文本中的指定内容,该怎么解决

shell，sed修改指定位置的文本中的指定内容
/b/xx 即在目录b下存在一个文件xx，文件xx的内容如下

<Host>
123224rsiskd1
sdfkldsfjkslf2
fdsjlfjlsdf3
fdjsofjs;f4
fjdsfdksfkd5
dsfkjgds6
</Host>

现在，我想在</Host>的前面一行，也就是 dsfkjgds6 和</Host>之间添加一行文字，文字如下
<Valve className ="a.b.c.d.e"/>

请问应该如何写？

[解决办法]

Assembly code

[root@RHEL6A tmp]# cat data7.txt <Host>123224rsiskd1sdfkldsfjkslf2fdsjlfjlsdf3fdjsofjs;f4fjdsfdksfkd5dsfkjgds6</Host>[root@RHEL6A tmp]# awk '{if ($0=="<Host>") printf("%s\n<Valve className =\"a.b.c.d.e\"/>\n",$0);else print $0}' data7.txt <Host><Valve className ="a.b.c.d.e"/>123224rsiskd1sdfkldsfjkslf2fdsjlfjlsdf3fdjsofjs;f4fjdsfdksfkd5dsfkjgds6</Host>[root@RHEL6A tmp]#