How to copy an xml tag and its value into another xml file under the same root tag

Question

I need to copy an xml tag and its value to another xml file under same root tag. Create the root tag if it doesn't exist.

Here is an input output example.

INPUT: string.xml
<resource>
    <string name="app_name">MyExampleApp</string>
    <string name="profile">My Profile</string>
    <string name="messages">My Messages</string>
</resource>

$ command "profile" string.xml string1.xml

OUTPUT: string1.xml
<resource>
    <string name="profile">My Profile</string>
</resource>

I was looking for that "Command" and options. Not necessarily in that order. Please help me out here. Any Linux/Unix/Mac command will do

Answer 1

Using XMLStarlet, you could delete all the string nodes under the root node whose name attribute is not profile:

$ xml ed -d '/resource/string[@name != "profile"]' string.xml
<?xml version="1.0"?>
<resource>
  <string name="profile">My Profile</string>
</resource>

Add -O after ed if you don't want the XML declaration line.