Learning Perl on Win32 Systems

Reading a Directory Handle

After we have a directory handle open, we can read the list of names with readdir , which takes a single parameter: the directory handle. Each invocation of readdir in a scalar context returns the next filename (just the basename—you’ll never get any slashes or backslashes in the return value) in a seemingly random order.^[82] If no more names exist, readdir returns undef. Invoking readdir in a list context returns all of the remaining names as a list with one name per element. Here’s an example of listing all of the names from your Windows directory:

$windir = $ENV{"WINDIR"};
opendir(NT, $windir) || die "no $windir?: $!";
while ($name = readdir(NT)) { # scalar context, one per loop
		print "$name\n"; # prints ., .., system.ini, and so on
}
closedir(NT);

And here’s a way of getting them all in alphabetical order with the assistance of sort:

$windir = $ENV{"WINDIR"};
opendir(NT, $windir) || die "no $windir?: $!";
foreach $name (sort readdir(NT)) { # list context, sorted
		print "$name\n"; # prints ., .., system.ini, and so on
}
closedir(NT);

The names include files that begin with a dot. This method is unlike globbing with <*>, which does not return names that begin with a dot. This method is a relic from Perl’s UNIX heritage, where the standard filename expansion normally does not include any files that begin with a dot.

In the current version of Perl for Win32, and the current version of the standard distribution, opendir fails on UNC paths. You can work around ...