If you want to grab each portion of the path, delimited by '/', you can do this (more on '/' later):

my $dir1 = 'c:/reports/temp1/temp2';
my $dir2 = 'c:/output';
my( @dirs ) = split /\//, $dir1;
$dirs[0] = $dir2;
foreach my $dir ( @dirs ) {
    $dir2 .= '/' . $dir;
    mkdir $dir2 or die $!;
}
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Note: For the sake of portability and simplicity, Perl allows you to separate directories with a '/' character, which is a whole lot easier to deal with than '\' characters. And you can do it that way on both a Windows system and a *nix system, from within a Perl script.