I want to change XML to Webconfig use Powershell

Question

i want to know how to change XML and Save

for example,this is test1.xml

<AAA_KEY>
<Account_key> 123AA03 </Account_key>
    <KEY ID = "User10036">
        <key1> #1199DERE45  </key1>
        <key2> 455DSuyeias  </key2>
</AAA_KEY>

and then,i have a web.config

<www>
    <KEY ID = "User10036">
        <user> user1 </user>
        <key1> xxxxxx  </key1>
<www>

so,i want to know how to read key1 , copy to web.config and save

for example

<www>
    <KEY ID = "User10036">
        <user> user1 </user>
        <key1> #1199DERE45  </key1>
<www>

Answer 1

Your xmls are not well formed... the KEY tag needs to be closed. I've edited it to how I think it should be below, change it in your question if that's not right.

# read the files as xml objects
[xml]$test1 = Get-Content C:\temp\test1.xml
[xml]$webconfig = Get-Content C:\temp\web.config

# for testing, I'm just going to create the objects. you don't need to do this.
[xml]$test1 = @"
<AAA_KEY>
<Account_key> 123AA03 </Account_key>
    <KEY ID = "User10036">
        <key1> #1199DERE45  </key1>
        <key2> 455DSuyeias  </key2>
    </KEY>
</AAA_KEY>
"@
[xml]$webconfig = @"
<www>
    <KEY ID = "User10036">
        <user> user1 </user>
        <key1> xxxxxx  </key1>
    </KEY>
</www>
"@

# set the value
$webconfig.www.KEY.key1 = $test1.AAA_KEY.KEY.key1

# save web.config
$webconfig.Save("C:\temp\web.config")