Perl find text and add line

Applications Programming
1

Hi All

I need to add a line to a file but after a certain block of text is found

The block of text looks like this

<RDF:Description RDF:about="urn:mimetype:video/quicktime"
                   NC:value="video/quicktime"

and i need to add this in the next line down ( note there is already something there so it need to be pushed down a line)

NC:useSystemDefault="true"

many thanks
A

2

sed, ok?

sed '/NC:value="video/a NC:useSystemDefault="true"' file
3

sed it fine, i have not used it before like this, can explain what is it doing?

4 
cat file1
abcd
efgh
<RDF:Description RDF:about="urn:mimetype:video/quicktime"
                   NC:value="video/quicktime"
ijkl

perl -pe 's!(NC:value="video/quicktime")!$1\nNC:useSystemDefault="true"!' file1
abcd
efgh
<RDF:Description RDF:about="urn:mimetype:video/quicktime"
                   NC:value="video/quicktime"
NC:useSystemDefault="true"
ijkl
5 
/NC:value="video/           ==> If this pattern is found
a                           ==> Append in the line next to the pattern
NC:useSystemDefault="true"  ==> With this text