Do any OS X apps ease Search and Replace across multiple files?

I'm looking for an OS X tool which allows me to search and replace a search string in multiple files. The requirements are the following:

• Search and Replace
• Search by regular expression
• Search across multiple files
• Search across nested directory structures
• Replace expression can use values from the search (Regular Expression)
• The tool has an easy to use user interface
• Preferably free

I know that some text editors like BBEdit have this functionality, but I would prefer a lightweight tool that doesn't require me to open the files for editing first.

If there aren't any tools to match these requirements, I would also consider a command line alternative. I know that perl and sed support something like this - a solution that I can define either as a Bash alias or function would be welcome in this case.

Solution 1:

I typically use TextMate:

TextMate (1) is/was a buy product, but TextMate 2 is currently under active openSource development on gitHub and free to use.

Solution 2:

Sublime Text is what I use, it's great!

Sublime Text:

• is free to evaluate (no time limit imposed)
• can search and replace
• can search by regular expression
• can search across multiple files
• can search across nested directory structures
• can use values from the search in replace expression
• has an easy to use user interface

Solution 3:

You don't have to open the files with BBEdit. You just point it to a folder. It's a very powerful tool, one that I've often used with large numbers of HTML files.