It would help immeasurably if you could provide some code showing how you originally create the time object. You might be using Time::localtime but that's only a guess.

Once it becomes clear quite how you are creating the time object it should be pretty simple to explain how to convert it to a string and back again.

Yes, it's with localtime

use 5.10.1;

use strict;
use Time::Local;
use Time::localtime;
use IO::File;

  my $ti = localtime;
  my $tf;
  my ($logFile, $logFileH);
  my $basePath = "c:\\las\\dump";
  my $processName = "dummy process";
  my $startState = "enabled";
  my $deaths = 4;
  my $diff;
  
  my $processNameOut;
  my $startStateOut;
  my $deathsOut;
  
  my $deathFile = "$basePath\\itrsDeaths.dat";
  my $deathFileH = new IO::File(">$deathFile") or logit("Can't open fi
+le: $deathFile for output.\n");

  printf $deathFileH ("%-35s%-9s %-5d %s\n", $processName, $startState
+, $deaths,$ti);

  if ( -f "$deathFile") {
    open(INIFILE,'<',"$deathFile") or logit( "Could not open death fil
+e $deathFile: $!");
    my @records = <INIFILE>;
    foreach my $record (@records) {
      my ($processNameOut, $startStateOut, $deathsOut, $ti) = $record 
+=~ /(\S+)\s+(\S+)\s+(\S+)\s+(\S+)?/;
    }
    close INIFILE;
  }
  else {
    open(INIFILE,'>',"$deathFile") or logit( "Could not create death f
+ile $deathFile: $!");
    close INIFILE;
  }
  
  sleep(2);
  
  $tf = localtime;
 
  $diff = getTimeDifferenceInSeconds($ti,$tf);
  
  say "The time difference in seconds is $diff";
    
  
  sub getTimeDifferenceInSeconds  {
  my ($t1,$t2) = @_;
  my $sec1 = $t1->sec;
  my $sec2 = $t2->sec;
  my $min1 = $t1->min;
  my $min2 = $t2->min;
  my $hour1 = $t1->hour;
  my $hour2 = $t2->hour;
  my $mday1 = $t1->mday;
  my $mday2 = $t2->mday;
  my $month1 = $t1->mon;
  my $month2 = $t2->mon;
  my $year1 = $t1->year;
  my $year2 = $t2->year;
  my $diff;

  my $es1 = timegm($sec1,$min1,$hour1,$mday1,$month1-1,$year1);
  my $es2 = timegm($sec2,$min2,$hour2,$mday2,$month2-1,$year2);

  $diff = $es2-$es1;

  return $diff;
}
  
  
  sub logit {
    print @_;
  #  print $logFileH @_ if ($ENV{ENABLE_ITRS_LOGGING});
  }
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Thanks for this code - that makes it all a good deal clearer. So, if all you are after is the time difference in seconds, why not just use epoch times throughout? You could even save both the epoch time and the localtime-as-string in the file if you want the file times to be easily understood by a non-machine reader.

 
#!/usr/bin/perl 
use strict; 
use warnings;

my $TESTFILE='/tmp/x';
unless (-f $TESTFILE){
    open(TF, '>',$TESTFILE) or die $!; 
    close(TF);
}

my $AGE_seconds = -r $TESTFILE ? int( (-M _) *60*60*24) : -1;
print "the file $TESTFILE is $AGE_seconds seconds old.\n";
[download]

As for the timelocal(), roll your own, with a simple regular expression you are all set. Just be careful to not match a date in the other fields.

> if you use a daemon, it will not work,

Fortunately, there's $^T to compensate:

$ touch 1
$ sleep 2
$ perl -wE '
    say 24 * 60 * 60 * -M "1";
    sleep 2;
    say time - $^T + 24 * 60 * 60 * -M "1";
'
2
4
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($q=q:Sq=~/;[c](.)(.)/;chr(-||-|5+lengthSq)`"S|oS2"`map{chr |+ord
}map{substrSq`S_+|`|}3E|-|`7**2-3:)=~y+S|`+$1,++print+eval$q,q,a,
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Thank you choroba, very insightful (you got my vote)... adding (time - $^T) to my snippets files...