Escaping special character stored in variables : perl

Hi

just for regular use i m working on small module written in perl for getting date in specified format like i have to specify date format and then seperator to seperate date i am 95% done. now i m sure explanation i gave is not good enough so i am putting output here :

C:\Documents and Settings\idc193577\Desktop>perl d.pl

    Usage : d.pl <date_format> ['<seperator>']

    Desc  :
    --> valid date_formats - dd   # day of month ( 01 - 31 )
                           - ddd  # 3 letter day name ( Mon Tue Wed ...)
                           - DD   # full day name ( Monday )
                           - DDD  # day of month and name in full ( 13 Friday )
                           - mm   # month no ( 01 - 12 )
                           - mmm  # 3 letter month name ( May Jun Jul ...)
                           - MM   # full month name ( February )
                           - yy   # last 2 digits of year ( 2009 -> 09 )
                           - yyyy # 4 digit year ( 2009 )

    --> valid seperator    - All Non Digits & Characters are valid.

    *** P.S : Specify seperator within single quotes like ','

C:\Documents and Settings\idc193577\Desktop>perl d.pl ddmmyy
Input Format : ddmmyy | Seperator : [] | Output : [130209]

C:\Documents and Settings\idc193577\Desktop>perl d.pl ddd 
Input Format : ddd | Seperator : [] | Output :[Fri]                                                                
C:\Documents and Settings\idc193577\Desktop>perl d.pl mmm 
Input Format : mmm | Seperator : [] | Output [Feb]                                                                
C:\Documents and Settings\idc193577\Desktop>perl d.pl MM  
Input Format : MM | Seperator : [] | Output : [February]  

C:\Documents and Settings\idc193577\Desktop>perl d.pl yyyymmdd "/"
Input Format : yyyymmdd | Seperator : [/] | Output : [2009/02/13/]

now i can put anything as a seperator other than WORDS & NUMBERS this is where problem is coming look in above output last "/" in red is not required so i want to remove this and in code i am doing this as :

my $seperator = "$ARGV[1]" # which is "/"
my $result      = "2009/02/13/" ; # hardcoded here 

$result =~ s/${$seperator}$// ; # delete seperator which is at last but its not working i even tries escaping with \e${seperator} but did not work. 
print $result ; 

thanks

keep it simple....

why not just not use substitution?

print "${separator}$MM${separator}$MM${separator}$YYYY\n";

thanks for reply problem is i can try any combination of date format it can be yyyymmdd/dd/mmdd/ddmmyy anything ...so i am not sure which one is coming first ....