Planning to add the below content after the closing tab into the main.xml
Keeping the below xml tag information into the ADD.txt file.
<student>
    <name>Bob</name>
    <id>0111</id>
     -----
</student>
Executing the following command: The information is adding above the tag </class>, Planning to add the ADD.txt content after the tag </class>
sed -i '/</class>/e cat ADD.txt' main.xml
