#!/usr/bin/perl -wT
use strict;
use Time::Piece;

my $daysago    = 28;
my $datadir    = "/var/adm";

# MMDDYY of 28 days ago
my $timestring = localtime(time-$daysago*24*60*60)->strftime("%m%d%y");
my $file       = "$datadir/backup.$timestring.log.Z";

-e $file     or die "File '$file' doesn't exist"; 
unlink $file or die "Couldn't unlink '$file'";