perl - ディレクトリを作成し、そこに adb ログを保存します

Question

現在のディレクトリに新しいディレクトリを作成し、作成したばかりの新しいディレクトリに adb ログを保存しようとしています。次のコードを試していますが、なぜか実行するたびにログが上書きされます。すべてのログを保存し、上書きしたくありません。

use POSIX;
use Getopt::Long;
our $timestamp;
our $mainlog_filename;
our $ostype = $^O;
our $ProcessObj;
$SIG{'INT'} = 'INT_handler';
$SIG{'TERM'} = 'INT_handler';
$SIG{'ABRT'} = 'INT_handler';
$SIG{'QUIT'} = 'INT_handler';

if($^O eq 'MSWin32') { 
    $SIG{'BREAK'} = 'INT_handler';
    use Win32::Process;
}

$split_val = join(':', @ARGV[0..(@ARGV-1)]);

@split_val = split(':',$split_val);
$counter=1;
foreach $sno(@split_val)
{
print "Serial Number $counter is $sno\n";
$counter++;
}

# Hash to translate number to month name
my $monthhash = {
    1  => 'Jan',
    2  => 'Feb',
    3  => 'Mar',
    4  => 'Apr',
    5  => 'May',
    6  => 'Jun',
    7  => 'Jul',
    8  => 'Aug',
    9  => 'Sep',
    10 => 'Oct',
    11 => 'Nov',
    12 => 'Dec',
};


$currdir = `pwd`; 
chomp $currdir; # gets current directory
$currdir =~ s/ \/[^\/]+$//; # removes the last / and everything after it
$new_dir = "adb logs";
$perm = 755;


sub makeDir {
  if (-e "$new_dir"){ problem("Directory $new_dir already exists.\n") } # Checks for existing
  mkdir ($new_dir,$perm) || problem("Error making Directory $new_dir\n");
  print "Content-type: text/html\n\n";
  print "$new_dir Directory has been created.\n";
  }
sub main
{
    my ($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst) = localtime(time);
    $mon  = $mon + 1;
    $mday = sprintf("%02d", $mday) if $mday <= 9;
    my $date    = $monthhash->{$mon}.$mday;
    $timestamp=$date."_".$hour."_".$min;
    foreach $sno(@split_val)
    {
    chomp($sno);
      $mainlog_filename = "adblogs_".$sno."_".$timestamp.".txt";
    }

    makeDir() unless -d $new_dir;

    my $adbcommand_logcat;
    my $adb_install_apk;
    my $adb_install_testapk;

    if($ostype eq 'MSWin32') {
        system("title Android");

        foreach $sno(@split_val)
        {
        chomp($sno);
        print "$sno\n";


        chdir $new_dir;
        $adbcommand_logcat = "start \"Android-Logcat\" cmd /c \"adb -s $sno logcat -v time | tee ".$mainlog_filename."\"";
        chdir $currdir;
        $adb_install_apk = "adb install xyz.apk";
        $adb_install_testapk = "adb install xyzTest.apk";

    $cmd = "adb -s $sno get\-state";
    my $cmdop = qx/$cmd 2>&1/;


    print $cmdop;


      if($cmdop =~ m/device/i) {

            system($adb_install_apk);
            system($adb_install_testapk); 
            system($adbcommand_logcat); 
        }
     else {
        print "Device is offline\n";
    }

    }
}
}
sub terminate
{
    print "\nTerminating script ...\n";
    system("adb kill-server");
   #if($ostype eq 'MSWin32') {
   #   $ProcessObj->Kill(0);
  #  }
    exit 0;
}

sub INT_handler
{
    terminate(); 
    exit 0;
}


main();

どんな助けでも大歓迎です。