Datemodif perl script

#!/usr/bin/perl

# datemodif <format> <fichier>
# ex : datemodif ymd tutu.txt
# ex : datemodif m-d tutu.txt
# ex : datemodif "D M Y" tutu.txt
#
# Heure de modif :
# s : 01-59
# m : 01-12
# h : 01-24
# i : 01-12 am/pm
#
# Jour de modif :
# d : 01-31
# D : Lun-Dim
# e : lun-dim
# F : Lundi - Dimanche
# g : lundi - dimanche
# M : 1-12
# N : Jan-Dec
# n ; jan-dec
# O : Janvier-Decembre
# o : janvier-decembre
# y : 02
# Y : 2002

%weekday=(
    "0"=>"Dim",
    "1"=>"Lun",
    "2"=>"Mar",
    "3"=>"Mer",
    "4"=>"Jeu",
    "5"=>"Ven",
    "6"=>"Sam",
);

%lweekday=(
    "0"=>"Dimanche",
    "1"=>"Lundi",
    "2"=>"Mardi",
    "3"=>"Mercredi",
    "4"=>"Jeudi",
    "5"=>"Vendredi",
    "6"=>"Samedi",
);

%month=(
    "1"=>"Jan",
    "2"=>"Fev",
    "3"=>"Mar",
    "4"=>"Avr",
    "5"=>"Mai",
    "6"=>"Juin",
    "7"=>"Juil",
    "8"=>"Aout",
    "9"=>"Sept",
    "10"=>"Oct",
    "11"=>"Nov",
    "12"=>"Dec",
);


%lmonth=(
    "1"=>"Janvier",
    "2"=>"Février",
    "3"=>"Mars",
    "4"=>"Avril",
    "5"=>"Mai",
    "6"=>"Juin",
    "7"=>"Juillet",
    "8"=>"Aout",
    "9"=>"Septembre",
    "10"=>"Octobre",
    "11"=>"Novembre",
    "12"=>"Décembre",
);

if (!@ARGV ) { 
	help();
	exit;
}

$file=pop;

if (!-e $file) {
   print "File $file not found, aborting.\n";
   print "Calling script with no arguments prints help\n" ;
   exit;
}

$arg = join " ",@ARGV;

$mtime = (stat($file))[9];
($sec,$min,$hour,$day,$mon,$year,$wday,$yday) = localtime($mtime);
$year+=1900;
$mon++;
if ($hour > 12) {
   $hour_ampm=abs($hour - 12); $p="pm"
} else {
   $hour_ampm="$hour"; $p="am"
}
$ssec=&paf($sec);
$mmin=&paf($min);
$hhour=&paf($hour);
$hhour_ampm=&paf($hour_ampm);
$dday=&paf($day);
$mmon=&paf($mon);
$yyear=substr($year,2,2);

$arg=" ".$arg;
$result = "";
$translated = 0;

foreach $letter (split //,$arg) {

$translated = 0;

# time
&pouet("s",$ssec);
&pouet("t",$sec);
&pouet("m",$mmin);
&pouet("u",$min);
&pouet("h",$hhour);
&pouet("g",$hour);
&pouet("i",$hhour_ampm);
&pouet("k",$hour_ampm);
&pouet("p",$p);
# day
&pouet("d",$dday);
&pouet("D",$day);
&pouet("W",($weekday{"$wday"}));
&pouet("w",lc($weekday{$wday}));
&pouet("X",$lweekday{$wday});
&pouet("x",lc($lweekday{$wday}));
# month
&pouet("M",$mmon);
&pouet("T",$mon);
&pouet("N",$month{$mon});
&pouet("n",lc($month{$mon}));
&pouet("O",$lmonth{$mon});
&pouet("o",lc($lmonth{$mon}));
# year
&pouet("y",$year);
&pouet("Y",$yyear);

$previousletter=$letter;
if (!$translated) { $result.=$letter }
}

$result=~s/^ //;
$result=~s/\^//;

print "$result";


sub pouet {
my ($in,$out) = @_ ;
if ($previousletter ne "^" && $letter eq $in) {
	$letter =~ s/$in/$out/g ;
	$result .= $letter;
	$translated=1;
}
return
}

sub paf {
my ($in)=@_ ;
if ($in < 10) {$in="0".$in}
return $in;
}

sub help {
print <<ENDHELP;
Output modification time and date in various format.

Usage :
$0 <optional format> [file]

Format arguments are :
     arg   value   (output)
 > Time 
      s : seconds  (01-59)
      t : seconds  (1-59)
      m : minutes  (01-12)
      u : minutes  (1-12)
      h : hour     (01-24)
      g : hour     (1-24)
      i : hour     (01-12)
      k : hour     (1-12)
      p : am or pm (am-pm)
 > Day 
      d : monthday (01-31)
      D : monthday (1-31)
      W : weekday  (Lun-Dim)
      w : weekday  (lun-dim)
      X : weekday  (Lundi-Dimanche)
      x : weekday  (lundi-dimanche)
 > Month
      M : month    (01-12)
      T : month    (1-12)
      N : month    (Jan-Dec)
      n : month    (jan-dec)
      O : month    (Janvier-Decembre)
      o : month    (janvier-decembre)
 > Year
      y : year     (02)
      Y : year     (2002)

To escape an argument, use ^
Edit the script ($0) to translate weekdays and months if you wish.

Examples :
 $0 ymd tutu.txt
 $0 m-d tutu.txt
 $0 D M Y tutu.txt
 $0 ^dd^mm^yy tutu.txt

ENDHELP
}