You can replace all occurrences of a specific string or regular expression with the return value of a BeanShell script if the Return value of a BeanShell snippet radio button is selected in the search dialog box.

You can use this, for example, to replace each occurrence of Windows with Linux, and each occurrence of Linux with Windows, by searching for the following regular expression:

(Windows|Linux)

And replacing it with the following BeanShell snippet:

_1.equals("Windows") ? "Linux" : "Windows"