A couple of nice tools

Thursday, August 13. 2009

I don't add tools to my toolbox very often. I tend to find that the time spent learning them outweighs the extra benefit I might obtain. Recently I found (or was pointed at) a couple of nice ones, though.

First is ack a nice grep replacement. Among other things it highlights what you're searching for, is automatically recursive, and knows how to ignore .svn and similar directories. Quite cute. It looks like it has a million bells and whistles, but it usually just Does the Right Thing (tm). "ack foo" usually gives me exactly what I want. So I just went looking for "CreateFunctionStmt" in the Postgres sources, and the output was really quite nice - much nicer than "grep -r" would have given me.

Second is Trang, a nifty tool to convert between the various languages for describing XML languages. So you can take a DTD and get an XML Schema or RELAXNG spec from it, for example. I used it to convert the (out of date) RELAXNG spec we had for the new XML explain output in Postgres into an XML Schema, and it worked perfectly. It will only output XML Schemas, it won't take them as input, but that still met my needs. It can also infer a schema from an example XML document, which is very nice indeed. There are limitations, to be sure, but it certainly beats starting from scratch, so it's a very definite time saver.

Posted by Andrew Dunstan in PostgreSQL at 19:26 | Comments (3) | Trackbacks (0)

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I'm annoyed at all the 'replace grep with ack' blog posts I see all over. Not because ack isn't a nice tool (it is), but because almost all the touted features allready exist in grep (the only one that I can't find is advanced usage of ack's --output option, although grep -o usually does the job). I have ack lying around, but never feel the need to use it instead of grep. 
 
Here's what I use for ack-style usage patterns (put it in your .bashrc): 
gr() { 
local dir 
[ $# = 1 ] && dir=. 
grep --color=auto --exclude-dir=.svn -rnE "$@" $dir 
} 
 
Do have a look a man grep. Lots of goodies.

#1 moltonel on 2009-08-14 17:29 (Reply)

Being annoyed seems an odd reaction, unless maybe you're a grep developer. 
 
And some of these features at least are relatively recent additions to grep. This machine I am writing on was set up less than 3 years ago and its grep doesn't feature --exclude-dir. Yes, I could upgrade it, but I tend not to replace system software unless I really need to, and I don't much like putting them in non-standard places either. And I work on plenty of boxes with software older than this one. 
 
Anyway, as we say in the perl world, TIMTOWTDI.

#1.1 Andrew Dunstan on 2009-08-14 17:58 (Reply)

Heh, on Debian, ack is a "Kanji code converter". The tool we're looking for is called ack-grep. 
 
Anyway, I mostly concur that man grep and export GREP_OPTIONS is your friend, especially because "grep" is hardwired into my fingers.

#2 Peter Eisentraut (Homepage) on 2009-08-16 00:38 (Reply)

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