比 ack-grep 更快更好用的东东：the silver searcher

比ack更快，而且还可以跟vim，textmate，emacs集成，推荐之。
https://github.com/ggreer/the_silver_searcher

The Silver Searcher

An attempt to make something better than ack (which itself is better than grep).

What's so great about Ag?

• It searches code about 3–5× faster than ack.
• It ignores file patterns from your .gitignore and .hgignore.
• If there are files in your source repo you don't want to search, just add their patterns to a .agignore file. *cough* extern *cough*
• The command name is 33% shorter than ack!

How is it so fast?

• Searching for literals (no regex) uses Boyer-Moore-Horspool strstr.
• Files are mmap()ed instead of read into a buffer.
• If you're building with PCRE 8.21 or greater, regex searches use the JIT compiler.
• Ag calls pcre_study() before executing the regex on a jillion files.
• Instead of calling fnmatch() on every pattern in your ignore files, non-regex patterns are loaded into an array and binary searched.
• Ag uses Pthreads to take advantage of multiple CPU cores and search files in parallel.

I've written several blog posts showing how I've improved performance. These include how I added pthreads,wrote my own scandir(), benchmarked every revision to find performance regressions, and profiled with gprofand Valgrind.

Building from source

1. Install dependencies (Automake, pkg-config, PCRE, LZMA):

   • Ubuntu: apt-get install -y automake pkg-config libpcre3-dev zlib1g-dev liblzma-dev

   • CentOS:

      yum -y groupinstall "Development Tools"
       yum -y install pcre-devel xz-devel 

   • OS X:

     • Install homebrew, then brew install automake pkg-config pcre
     • Or install macports, then port install automake pkgconfig pcre

   • Windows: It's complicated. See this wiki page.

2. Run the build script (which just runs aclocal, automake, etc):

   • ./build.sh

3. Make install:

   • sudo make instal