Sometimes within an OS X application you might want to search and replace all single tabs with two tabs, for example, or remove double carriage returns. However, if you type a Tab or hit Return in the search field of an app, it won’t have the desired effect. There’s a simple trick that can be used.
Open the search box as usual (i.e. within TextEdit by hitting Command + F), then hold Option while hitting Tab or Return. Doing so in most OS X apps will insert an “invisible” tab or carriage return character, allowing you to search for tabs and carriage returns within the document. You won’t see a symbol for each. Rather you’ll literally insert a tab or line break into the search field–and you can use the Up cursor key to return to the previous line in the case of a line break.
The ‘invisibles’ can be combined with any other search term. To search for a tab preceding the word “the”, for example, you would hold Option, then hit Tab, then type the.