Thanks very much. I am not able to print the contents of the file. I'll read about glob and the explanation in the perlop. Thank you!

my $dir = 'input_files';
die "can't opendir $!" unless opendir DIR, $dir;
while (defined(my $file = readdir DIR)) {
    do {
        print "The directory and file are $dir/$file\n";
        die "Can't open input file $!" unless open IN, "< $dir/$file";
        use File::Glob ();
        while (defined($_ = glob(' IN '))) {
            print $_;
        }
    };
}
closedir DIR;
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Output

perl create_indivo_schemas.pl
Name "main::IN" used only once: possible typo at create_indivo_schemas
+.pl line 18.
The directory and file are input_files/allergies
INThe directory and file are input_files/immunizations
INThe directory and file are input_files/..
INThe directory and file are input_files/.
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