Archiving or removing few data from log file in real time Post: 302907380

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Top Forums Shell Programming and Scripting Archiving or removing few data from log file in real time Post 302907380 by rbatte1 on Friday 27th of June 2014 12:17:45 PM

06-27-2014

Moderator

Surely cat filename|wc -l adds a process and therefore considerable extra time. Would wc -l filename not be quicker?

Anyhow, is the file being appended to as in-use all the time or is it separate operations. Consider these two (probably not exactly true, but just for an example)

Code:

for i in 1 2 3 4 5
do
   echo "Hello $i" >> filename
   sleep 5
done

versus

Code:

for i in 1 2 3 4 5
do
   echo "Hello $i"
   sleep 5
done >>filename

In the first, you have five discreet "open-append and close" operations. In the second you have one, so in the gaps between the echo statements, the file remains open. If you delete the data and write the file back, where does the subsequent output go? If you rename the file, then the output follows the old file.

Like Corona688 says, we need to know what is generating the messages. It may be that you have to stop that process whilst you manipulate the file, then restart it if there is no signal you can send to get it to switch logs.

Robin

rbatte1

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LEARN ABOUT PHP

sleep

SLEEP(3)								 1								  SLEEP(3)

sleep - Delay execution

SYNOPSIS

       int sleep (int  $seconds)

DESCRIPTION

	Delays the program execution for the given number of $seconds.

PARAMETERS

	      o $seconds
		- Halt time in seconds.

RETURN VALUES

	Returns zero on success, or FALSE on error.

	If  the  call  was interrupted by a signal, sleep(3) returns a non-zero value. On Windows, this value will always be 192 (the value of the
       WAIT_IO_COMPLETION constant within the Windows API). On other platforms, the return value will be the number of seconds left to sleep.

ERRORS
/EXCEPTIONS
	If the specified number of $seconds is negative, this function will generate a E_WARNING.

CHANGELOG

       +--------+---------------------------------------------------+
       |Version |						    |
       |	|						    |
       |	|		     Description		    |
       |	|						    |
       +--------+---------------------------------------------------+
       | 5.3.4	|						    |
       |	|						    |
       |	|  Before PHP 5.3.4, on  Windows,  sleep(3)  always |
       |	| returns  NULL when sleep has occurred, regardless |
       |	| of whether the sleep was interrupted or not.	    |
       |	|						    |
       +--------+---------------------------------------------------+
EXAMPLES

       Example #1

	      sleep(3) example

	      <?php

	      // current time
	      echo date('h:i:s') . "
";

	      // sleep for 10 seconds
	      sleep(10);

	      // wake up !
	      echo date('h:i:s') . "
";

	      ?>

	       This example will output (after 10 seconds)

	      05:31:23
	      05:31:33

SEE ALSO

       usleep(3), time_nanosleep(3), time_sleep_until(3), set_time_limit(3).

PHP Documentation Group 														  SLEEP(3)