I see a couple of issues.

1. You neglected to remove the trailing newline from your input. You can take care of this by chomping the value:

   chomp(my $dir = <STDIN>);

2. You omitted a semicolon on line 8:

   chdir($dir);

3. You neglected to declare your variables @files and $file on lines 9 and 10:

   my @files = <$dir/*>;
   foreach my $file (@files)
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4. You omitted a comma (Comma Operator) from your print statement. Without it, Perl will read that as printing "\n" to the lexical file handle in $file.

   print $file, "\n";

You also might want to read Markup in the Monastery since you haven't followed site protocol. Rather than using a glob, I'd also use opendir, readdir and closedir to protect yourself from typos and pathological file names.

#!/usr/bin/perl

use strict;
use warnings;

print "Enter name of directory (fully qualified path): ";
chomp(my $dir = <STDIN>);
opendir my($dirhandle), $dir or die "No such directory: $dir";
my @files = readdir($dirhandle);
closedir($dirhandle);
foreach my $file (@files)
{
print $file, "\n";
}
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