As others have pointed out this is Perl's "statement modifier" idiom. Perl has many shorthand ways of achieving things and that is a large part of what gives Perl its power to be concise and clear.

consider the following:

my $filename = "$root/$path/$name";
open my $fileHandle, '<', $filename or die "Failed to open $filename: 
+$!";
print $fileHandle "$_:    $results[$_]\n" for 1 .. $#results;
print $fileHandle "Total: $results[0]\n";
[download]

which deflares a variable in the middle of a file open statement, uses the "or die" idiom to check the result of an open, uses a for loop taking a range as a statement modifier and uses string interpolation to construct a file name from components and to build the strings to be printed.

The result is concise, lucid and robust.