From: Panagiotis Atmatzidis <atma@...>
Date: 2009-12-13T22:37:24+09:00
Subject: Re: Question about file management [read]

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Hello,

On 13 Δεκ 2009, at 1:20 μ.μ., Robert Klemme wrote:

> On 12.12.2009 21:05, Panagiotis Atmatzidis wrote:
>> A salut to the list,
>> 
>> I need read info from a file, extract the info that I want which is the date and IP and dump them into a database (mysql).
>> 
>> However, this file gets constantly updated, sits on /var/log/.
>> 
>> Until now I have used just the file.open and file.read methods. However, I feel that both ways are not suitable for what I want to do, because I will need to make a selection between old and new entries every time my script reads the file to extract info.
>> 
>> What is the *standard* (or best) way to manage this situation?
>> 
>> Here is the class which reads the file:
>> 
>> class ReadIPs
>>   def self.ip(log)
>>     file = File.open(log)
> 
> Ha!  There you are not using block form of File.open and you do not have the #close in ensure! :-)

I don't understand what do you mean by 'ensure'.

> 
>>     file.each_line do |line|
>>       if line.include?("Ban")
>>          a = line.split(" ")
>>          date = a[0]
>>          ip = a[6]
>>          puts "date: #{date} IP: #{ip}"
>>       end
>>     end
>>     file.close
>>   end
>> end
>> 
>> I use File.open now but I should use something like File.append or similar? Note that I will never write to this file, it's just the file that contains the info. Every time a new line appears that contains the word "Ban" I want to trigger this...
>> 
>> Best regards
> 
> I can't test it right now but this might be an option.
> 
> File.open log do |io|
>  loop do
>    io.each do |line|
>      # whatever...
>    end
> 
>    # v2: pos = io.tell
>    sleep 10 # whatever interval is appropriate
>    # v1: io.seek(0, IO::SEEK_SET)
>    # v2: io.seek(pos, IO::SEEK_CUR)
>  end
> end
> 
> Maybe you have to do one of the variants to clear eof flag:
> 
> v1: seek to offset 0 of current position
> v2: fetch the position before the sleep and then seek to that absolute position
> 
> Kind regards
> 
> 	robert

Oh, this solutions, might work but I think that it's a bit overcomplicated for me. I did not used IO and "seek" yet...

I found online [1] a few examples but I did not had the time to test them.

Maybe something like: 

file   = File.open(path, File::WRONLY|File::APPEND)

Will do.


> -- 
> remember.guy do |as, often| as.you_can - without end
> http://blog.rubybestpractices.com/

[1] http://pleac.sourceforge.net/pleac_ruby/fileaccess.html

Panagiotis (atmosx) Atmatzidis

email:	atma@convalesco.org
URL:	http://www.convalesco.org
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The wise man said: "Never argue with an idiot. They bring you down to their level and beat you with experience."

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