[olug] From Tejaswi: Unix Utils in Windows (fwd)

[David Walker]

The secret I use is to presume that the log file after logrotate will always 
be smaller than the log file before logrotate.  This should be true nearly 
all of the time unless you have unusual log usage patterns.

To programmatically open the log file
Record the current_file size
 If current_file_size is larger than previous_file_size
  seek previous_file_size
 else
  seek 0; 
 end if
 read until eof

To use tail instead of programmatically opening the log and seeking what you 
need you would do
Record the current_file size
 If current_file_size is larger than previous_file_size
  tail -c (current_file_size - previous_file_size) FILENAME
 else
  cat FILENAME
 end if
 read until eof

but this method could result in a few lost characters if a write occurred 
between reading the current file size and the tail command.


On Sunday 13 February 2005 10:44 am, Jon Larsen wrote:
> -------- Original Message --------
> Date:  Fri, 11 Feb 2005 13:50:18 -0800 (PST)
> From:  Tejaswi Manjunath <tejas at zoonic.com>
> Reply-To:  tejas at zoonic.com
>
> ---------------------------------------------------------------------------
>-------
>
> Subject: tail in windows ?? need more options !!
> Body:
> i am trying to use tail command in windows, i downloaded the Win 2003
> Server Resource Kit and got hold of tail.exe, so it does take options of
> -c, -f, -q, -n, -v !!!
>
> my problem is i am looking for using the option of -r - as my program is
> supposed to read the updated contents of the file, and i am thinking of
> scanning the file backwards will get me to the point i want to stop
> reading easily and faster....keeping in mind log rotate that occours on
> log files....
>
> (i know there is another way of doing this also - keep track of the last
> scanned file, its size, last record, its size, and then do -> tail -c
> BYTES FILENAME, and get the required input only....but this will totally
> screw up cos of log rotate !!!)
>
> Any suggestions I would appreciate any help !!! Thanks guys
>
> by the way this is for a deamon of unix that could be installed on
> windows....
>
>
> ---------------------------------------------------------------------------
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