How to use sed to insert lines in a file

[McGrawh]

I am new to Sed and would like to know that how to use sed to insert lines in a file. Can any body tell me that how can i do so? Does any body knows about it? Kindly provide me the correct solution for the above issue. Any kind of help on the above issue would be appreciated.

[Praetor]

For that you need to just add one at the end. For that you need to just type in sed '10s/$/\ntext to add/' or sed '10a text to add' Both these line will help you to insert a line in a text file.

[kelfro]

I don't know but you can try the following code:-

x="this is the line"
sed '$ i '"$x"'' file