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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is_executable

IS_EXECUTABLE(3)							 1							  IS_EXECUTABLE(3)

is_executable - Tells whether the filename is executable

SYNOPSIS

       bool is_executable (string  $filename)

DESCRIPTION

	Tells whether the filename is executable.

PARAMETERS

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RETURN VALUES

	Returns TRUE if the filename exists and is executable, or FALSE on error.

EXAMPLES

       Example #1

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	      $file = '/home/vincent/somefile.sh';

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ERRORS
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NOTES

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SEE ALSO

       is_file(3), is_link(3).

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