File::Path (part of core) has mkpath()

There is the File::Path module (in the standard distribution of Perl even), which does exactly that, create intermediate directories if they don't exist.

Path::Class is also capable of this, if you prefer an OO interface. See its documentation on the $dir->mkpath method.

use Path::Class qw(dir);
dir("foo", "bar")->mkpath;

what's wrong with ...

system( "mkdir -p $dirname" );

Might be a little heavier that you want, but File::Flat also does this, or rather it lets you just write a file somewhere and it sorts all the details out for you.

File::Flat->write( '/some/path/that/might/exist.txt', $contents );

Of course, the neatest thing is that this...

File::Flat->canWrite( '/some/path/that/might/exist.txt' );

... also "means what you think", that is, "Can I write to the file, or create the file, or create as many directories as are needed".

Great for writing installer-type applications.

$path =~ s[/][\\]g;
system "md $path";

Here is somthing I wrote to do what you need.

#Note this is windows centric
use strict;

make_dir("c\:\\this\\is\\a\\deep\\subdirectory\\");

sub make_dir {
	my ($inpath) = @_;	#Full directory path
	my $path = "";		#Storage path

	#Loop through the sections
	foreach(split/\\/,$inpath) {
		#Add to path
		$path .= $_ . "\\";

		#Elimnate the drive and check to see if path exists
		if(!/\:/ and !-e $path) {
			#If not then make it
			mkdir $path;

			#Show status for demo
			print "Makeing $path\n";
		}
	}
}