Grep 2G source tree in 0.23 seconds. A speed up of more than 10 fold.
It uses a search engine before using grep. The search engine is beagle, thus the name beagrep.
For more details, visit [[http://baohaojun.github.com/beagrep.html][my github page]] (man page included).
[[https://github.com/ggreer/the_silver_searcher][Ag (AKA the silver searcher)]] claims to be very fast, beating [[http://beyondgrep.com/][ack]] and GNU grep.
I compared ag and beagrep on my laptop:
| Model | CPU | Memory | |---------------+------------------------------------------+--------| | Thinkpad T420 | Intel(R) Core(TM) i5-2520M CPU @ 2.50GHz | 8G |
** ag speed
cd ~/src/android time ag readlink . The first time it took 3 minutes, the second time it took 8 seconds, very impressive! I think if I had learned about it earlier I probably wouldn't have started working on beagrep in the first place, because I would have thought it is quick enough already.
** beagrep speed
time beagrep -e readlinkThe first time it took 30 seconds, the second time it took 0.42 second.
Another test is done on Linux kernel source code, where ag takes 1m35s/1.8s for cache hot/cold, while beagrep takes 15s/0.25s respectively.
(The claim that it took 0.23 second to grep 2G Android source code is achieved on my Dell Optiplex 960).
** Pros
Very fast
Output format compatibility with grep, so it can be used by, for e.g., Emacs grep-mode directly.
Match not only file content, file names too, like locate(1).
** Cons
You need build the search engine database beforehand (the first time you do this will take a long while, but subsequent updating is reasonably fast)
Works on whole words only: can not use partial word (=beagrep -e readli=) to find =readlink=.
Other grep like tools
Ack's author Andy Lester has written [[http://betterthangrep.com/more-tools/][a nice intro]] about all kinds of tools for searching source code.
Of particular interest to beagrep is Google's Code Search tool.
To-do
Push beagrep into Debian distribution.
Acknowledgment
Thank the Beagle project for making the original engine. And of course, the Apache Lucene project.
Thank LDD's author for saying ``(LDD) is the result of hours of grepping'' and getting me hooked to grep forever.
Last but not least, I submitted this README on [[http://redd.it/14tybj][reddit]], and has refined it several times according to the comments there. To those who commented: thanks, I have learned from you!