use Data::Dumper;
my %envron;
while (<DATA>) {
		chomp;
		my ($key, $value) = /(.+)=(.*)/;
		next unless defined $key;
		$value =~ s/\$(\w+)/$environ{$1}/g;
		$environ{$key} = $value;
}	
print Data::Dumper->Dump([\%environ], ["*environ"]);

__DATA__
myfile=test.log
mydir=/kelly/$myfile
longdir=/$myfile$mydir

__OUTPUT__
%environ = (
             'longdir' => '/test.log/kelly/test.log',
             'mydir' => '/kelly/test.log',
             'myfile' => 'test.log'
           );