The regular expression to find is entered here. You can click on the zoom button at the end of the line for multi-line input. The regular expression cannot be empty.
A regular expression is a sequence of characters forming a search pattern for matching text. There are some useful regular expressions in the Library and more detail in the Regular Expression reference guide.
The text to replace is entered here. You can click on the zoom button at the end of the line for multi-line input. This box can be left empty if you want to replace with nothing, though you will be warned.
Dot matches newline (aka Single-line mode. Changes the meaning of the dot (.) so that it matches every character (instead of every character except \n).)
Multi-line anchors (Changes the meaning of ^ and $ so they match at the beginning and end, respectively, of any line, and not just the beginning and end of the entire file).
The last two options will have no effect when reading a file in line-by-line mode. (File reading settings)
