Trapping a kill command sent to a script and using it to send an EOF to a subprocess before killing Post: 302880579

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Top Forums UNIX for Advanced & Expert Users Trapping a kill command sent to a script and using it to send an EOF to a subprocess before killing Post 302880579 by DeCoTwc on Friday 20th of December 2013 04:55:13 PM

12-20-2013

Registered User

Trapping a kill command sent to a script and using it to send an EOF to a subprocess before killing

I originally had a script written in pure shell that I used to parse logs in real time and create a pipe delimited file that only contained errors. It worked but it was using a lot of memory (still not clear on why). I originally got around this by writing a wrapper for the script that ran on cron and periodically killed the script and started a new instance. This worked for a while, but was still too heavy. So, I rewrote the parsing logic in awk instead of shell and the memory and CPU utilization dropped completely.

So now, I have this script running, but every 15 minutes the cronjob kills it and starts a new instance. What I want to do now is have my awk section of the script building out arrays, and when the cron kicks in, it sends an EOF to the awk so it can dump it's info into a separate file before it's killed and a new instance is started. Below is my code. What I want to do is add blocks to the awk section that creates arrays, and then add an end block to it that dumps the values from those arrays into a file. So, I need to trap the kill command and then have it send an EOF to awk, then kill the script and start a new instance.

Code:

#!/bin/bash
######################################################
# Program:      logGen.sh
# Date Created: 22 Aug 2012
# Description:  parses the manager log in real time into daily error files
# Date Updated: 27 Nov 2013
#		|_moved all data parsing logic to awk instead of shell
#		|_Need to analyze memory/CPU usage and consider changing
#		|_restart frequency in cron
# Developer:    Redacted (Senior Support Engineer)
######################################################
#Prefix for pid file
pidPrefix="logGen"
#output direcory
outDir="/opt/Redacted/logs/allerrors/"
#Simple function to see if running on primary
checkPrime ()
{
  if /sbin/ifconfig eth0:0|/bin/grep -wq inet;then isPrime=1;else isPrime=0;fi
}


#function to kill previous instances of this script
killScript ()
{
  /usr/bin/find /var/run -name "${pidPrefix}.*.pid" |while read pidFile;do
    if [[  "${pidFile}" != "/var/run/${pidPrefix}.${$}.pid" ]];then
      /bin/kill -- -$(/bin/cat ${pidFile})
      /bin/rm ${pidFile}
    fi
  done
}


#Check to see if primary
#If so, kill any previous instance and start log parsing
#If not, just kill leftover running processes

checkPrime
if [[ "${isPrime}" -eq 1 ]];then
  echo "$$" > /var/run/${pidPrefix}.$$.pid
  killScript
  tail -F -n0 /opt/Fabrix.TV/logs/manager_proxy.log|awk -v dir=$outDir '{OFS="|"}
{
  if ($3 == "E")
  {
    file="allerrors."$1".log"
    gsub("/",".",file)
    if ($9 ~ /@/)
      print $1,$2,$8,$9,substr($0, index($0,$10)) >> dir file
    else {if ($8 !~ /@/)
      print $1,$2,$7,"NULL",substr($0, index($0,$8)) >> dir file
    }
    fflush(stdout);
  }
}'
else
  killScript
  exit 0
fi

DeCoTwc

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LEARN ABOUT DEBIAN

pperl

PPERL(1p)						User Contributed Perl Documentation						 PPERL(1p)

NAME

       PPerl - Make perl scripts persistent in memory

SYNOPSIS

	 $ pperl foo.pl

DESCRIPTION

       This program turns ordinary perl scripts into long running daemons, making subsequent executions extremely fast. It forks several processes
       for each script, allowing many processes to call the script at once.

       It works a lot like SpeedyCGI, but is written a little differently. I didn't use the SpeedyCGI codebase, because I couldn't get it to
       compile, and needed something ASAP.

       The easiest way to use this is to change your shebang line from:

	 #!/usr/bin/perl -w

       To use pperl instead:

	 #!/usr/bin/pperl -w

WARNINGS

       Like other persistent environments, this one has problems with things like BEGIN blocks, global variables, etc. So beware, and try checking
       the mod_perl guide at http://perl.apache.org/guide/ for lots of information that applies to many persistent perl environments.

Parameters
	 $ pperl <perl params> -- <pperl params> scriptname <script params>

       The perl params are sent to the perl binary the first time it is started up.  See perlrun for details.

       The pperl params control how pperl works. Try -h for an overview.

       The script params are passed to the script on every invocation. The script also gets any current environment variables, the current working
       directory, and everything on STDIN.

Killing
       In order to kill a currently running PPerl process, use:

	 pperl -- -k <scriptname>

       You need to make sure the path to the script is the same as when it was invoked.

       Alternatively look for a .pid file for the script in your tmp directory, and kill (with SIGINT) the process with that PID.

ENVIRONMENT

       pperl uses the PPERL_TMP_PATH environment variable to determine the directory where to store the files used for inter-process
       communication.  By default, the subdirectory .pperl of the user's home directory is used.

BUGS

       The process does not reload when the script or modules change.

       $^S is not represented identically with respect to perl, since your script will be run within an eval block

AUTHOR

       Matt Sergeant, matt@sergeant.org. Copyright 2001 MessageLabs Ltd.

SEE ALSO

       perl. perlrun.

perl v5.14.2							    2011-11-15								 PPERL(1p)

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