now what i had tried actually replaces the xxx1.data , i do not want to delete the string only add new text before it.

What have you tried? Show us some code...

If you tried 

s[\w\w\w1\.data][$testname/]g

[download]
you might consider 
s[(\w\w\w1\.data)][$testname/$1]g

[download]
instead.

The $1 stands for the text enclosed in the first set of round brackets in the pattern.

In reply to Re: how to modify the text in file by Thilosophy
in thread ho w to replace a occurence of string by other string by Anonymous Monk

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