From: Dan Zwell <dzwell@...>
Date: 2007-08-29T15:25:59+09:00
Subject: Re: Help parsing simple structured data.

Nuby Ruby wrote:
> Dan,
> 
> That works perfectly, thank you a lot! This type of data I end up dealing
> with day-in and day-out, and this will help a lot.
> 
> Craig
> 
> On 8/28/07, Dan Zwell <dzwell@gmail.com> wrote:
>> Nuby Ruby wrote:
>>> I'm rather new to Ruby and am trying to figure out how to parse some
>>> structured data.. This is pretty much the most common problem I run into
>>> and it'd be *really* helpful to see an example to wrap my head around
>> blocks
>>> & hashes
>>>
>>> The data I'm working with is the output of `df -h` which looks like this
>> :
>>>
>>> Filesystem            Size  Used Avail Use% Mounted on
>>> /dev/md0              9.9G  1.6G  7.8G  17% /
>>> /dev/md1               60G  154M   57G   1% /data
>>> /dev/sda1              99M   12M   83M  13% /boot
>>>
>>> In the end what I'd like to end up with is to be able to say print
>>> hash[md0(size)] and have it
>>> return 9.9G or hash[sda1(Mount)] and have it show the mountpoint of
>> /boot
>>> If anyone could help I'd really appreciate it.
>>>
>>> Craig
>>>
>> Try this:
>>
>> rows = `df -h`.split("\n")[1..-1]
>> hash = Hash.new {|hash, key| hash[key] = {}}
>> rows.each do |row|
>>    data = row.split /\s+/
>>    device = data[0].sub(%r|^/dev/|, "")
>>    %w{size  used  avail  use  mount}.each_with_index do |field, column|
>>      hash[device][field] = data[column+1]
>>    end
>> end
>>
>> After running it, you should be able to find your data in
>> hash["md0"]["size"] or hash["sda1"]["mount"].
>>
>> Does this work for you?
>>
>> Dan
>>
>>
> 
Craig,

By the way, I just realized that my script assumes that the mount point 
has no spaces. Nothing horrible will happen if it does, but 
hash[device]["mount"] will only contain the first word, like "/d/My" of 
"/d/My Documents". If you want to fix that, you could replace a few of 
the lines in the above script with these:

 >>    %w{size  used  avail  use}.each_with_index do |field, column|
 >>      hash[device][field] = data[column+1]
 >>    end
 >>    hash[device][mount] = data[5..-1].join(" ")

Have fun,
Dan