Find Replace not working in Notepad++

Notepad++ will do just fine.

Search string:

 xyz

Replace string:

\r\nxyz

You will also need to set the "Search Mode" to "Extended" (lower left group box in the Replace dialog) so that Notepad++ honors escape codes.

Some background: "\r\n" is the escape code for carriage-return, the standard for new lines in Windows. Unix-style systems use simply \n (newline). Most IDEs, Notepad++ included, will understand both styles and portray them each with new lines, but core Windows utilities do not understand \n as being equivalent to \r\n, so the latter is usually the most appropriate if the file is intended to be used in Windows environments.

You have to escape the {} like so:

\{\$([a-zA-Z_]*)\}

I assume Geany and rubular.com don't use PCRE (or they use it differently). Please note that {} are usually used to denote quantifiers.

Without having checked the source, I can only assume that Notepad++ tries to be too smart before passing the regular expression to the PCRE library. If I run the following code in PHP:

echo preg_match( '{\$([a-zA-Z_]*)}', '{$something}' );

It prints 1 right away. No need to escape anything.

Sorry that I can't explain it :(