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egrep 

        # Rake::FileList.egrep

(from gem rake-13.0.6)
### Implementation from FileList
---
    egrep(pattern, *options) { |fn, count, line| ... }

---

Grep each of the files in the filelist using the given pattern. If a
block is given, call the block on each matching line, passing the file
name, line number, and the matching line of text.  If no block is given,
a standard emacs style file:linenumber:line message will be printed to
standard out.  Returns the number of matched items.

This is MURDOC! A Ruby documentation browser inspired by Smalltalk-80. It allows you to learn about Ruby by browsing through its class hierarchies, and see any of its methods.