I am unable to use this function in proper way.. When I am calling this function instead of fork , it just detaches from ssh session but cant process the exact function system(...) that we are really intended for.. I am giving u the modified code... Please come up with exact implementation of daemonize() which will both run the intended function in background..and detatch from ssh session.

#!/usr/bin/perl -w
use strict;
use warnings;
use Getopt::Long;

#variable declaration
my $exec_mode;
my $param;
my $paramfile;
my $log_loc= "/logs/default_log.txt";
my $interv =2;

GetOptions( "e=s" => \$exec_mode, "p=s" => \$param, "pf=s" => \$paramf
+ile, "l=s" => \log_loc, "i=i" => \$interv);

    if($exec_mode eq 'start')
    {
        if( $paramfile eq NULL)
        {
               &startsar ($param, $interv);
        }
        else
        {
               &startsar ($paramfile, $interv);
        }
    elsif($exec_mode eq 'stop')
                            {
            &stopsar ( $log_loc);
                            }
    else
              {
    print " usage sarexec -arguemrnts are-\n -e <start>/<stop>\n -p <p
+arams> \n -pf <param_file> \n -l <location> (by default location is '
+/logs/default_log.txt')\n -i <interval> ( by default interval is 2)\n
+ "
              }

sub startsar 
{ 
              
              if (substr($_[0],0,1) eq "-")
                {
                    my $pid = fork();
                            if($pid>0)
                            {
                             #parent
                            }
                           else
                           {
                            system("sar  -o logfile $_[0]  $interval 0
+ > /dev/null&"); # this utility must run in background and able to cl
+ose the script
        exit 0;
                           }   
                        
                }
                else 
                {
                  chomp $_[0];
                  my $param;
                            open FH,"< $_[0]" or die"cant open the fil
+e";
         $param = <FH>;
         close FH or die "cant close the file";
         chomp($param);
                            my $pid = fork();
                            if($pid>0)
                            {
                             #parent
                            }
                           else
                           {
                            system("sar  -o logfile $param   $interval
+ 0 > /dev/null&"); # this utility must run in background and able to 
+close the script
        exit 0;
                           }
                  }
}

sub stopsar
{
    system("kill \$(pidof sadc)");
      system("sar -f logfile>>$_[0]");
}
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