I do in file search a lot, and used to love grep. Then I learn the existence of egrep, so I switched to benefit from the advanced regexp. Then I discovered the Eclipse search tool. Much easier to use that grep. Then I found ack : fast, easy, powerful. And now I use grin, which is smooth for pythonistas. I know there is also a couple of this kind of tools with a GUI.

So what tool do you use, and why do you think it's the best. Practical features generally are :

• fast to fire and use;
• speedy processing;
• automatically ignore useless files;
• colored output;
• output lines, filename, context;
• allow complex regexp;
• allow a custom filtering and ouput;
• GUI + command line intergation;
• let you open an editor from the result set.

There are some related posts on SO :

• http://stackoverflow.com/questions/87350/what-are-good-grep-tool-for-windows
• http://stackoverflow.com/questions/981601/colorized-grep-viewing-the-entire-file-with-highlighting
• http://stackoverflow.com/questions/1028107/is-there-some-unix-util-that-will-allow-me-to-grep-multiple-files-with-little-type
• http://stackoverflow.com/questions/1027906/unix-find-grep-syntax-vs-awk