There is also the incredibly handy and usefull File::Find::Rule module:

use strict;
use File::Find::Rule;

my $commonField = 'Perl';
my $responseDir = '.';

my @files = File::Find::Rule->grep($commonField)->file->in($responseDi
+r);
print "I found '$searched_word' in $_" for @files;
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From the prompt: grep -l keyword *

Lazy perl way: $filename = `grep -l keyword *`

or

# Exits as soon as a match is found.
# only reads a line in at a time, not the entire file.

sub find_file {
   my ($dir_name, $keyword) = @_;

   my $file_name;
   my $file_path;

   my $dh = DirHandle->new($dir_name)
   or die("Can't read directory: $!.\n");

   while (defined($file_name = $dh->read())) {
      $file_path = "$dir_name/$file_name";

      next if ($file_name eq '.');
      next if ($file_name eq '..');
      next unless (-f $file_path);

      my $fh = FileHandle->new($file_path, 'r')
      or warn("Can't read file $file_name: $!.\n");

      while (defined($_ = $fh->getline())) {
         return $file_name if (index($_, $keyword) != -1);
      }
   }

   return undef;
}
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What do you want to happen if there is more than one file with the keyword? The (non-perl) grep utility is the usual way to solve this problem.

Guessing that you don't have system grep, you should generate a list of all filenames of interest with glob. Then open each and loop through the contents trying to match the keyword with the match operator, m/APPLES/. If a match is found, note the filename and go on to the next. That can be done in a way that generates an array of qualified files, using push.

I know for a fact that there will be only one UNIQUE KEYWORD, which will not be repeated in any other file

As they say, assumption is the mother of all foul-ups. The computer does exactly what it's told. At some point, someone will tell it to place the keyword in more than one file. At that point, things will break if you haven't decided to deal with it gracefully.

thor

Feel the white light, the light within
Be your own disciple, fan the sparks of will
For all of us waiting, your kingdom will come

opendir (DIR, "$responseDir") or die "could not open $responseDir :$!\
+n";
foreach $file ( readdir(DIR) ) {
  open THISFILE, "$responseDir/$file";
  my @newFile = grep { /$commonField/ } <THISFILE>;
  if ( @newFile ) {
    # If there were any contents, this is our file.
    $matchedfile = $file;
    close THISFILE;
    last;
  }
  close THISFILE;
}
closedir(DIR);
print "Matched file $matchedfile.\n";
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I tested a slight variation of this. You'll definitely want to re-test this, but I think it works.

--J

opendir (DIR, "$responseDir") or die "could not open $responseDir :$!\
+n";
my @newFile = grep { $commonField -f $responseDir/$_ } readdir(DIR);
closedir(DIR);
[download]

grep and glob are often very useful, for example:

my $dir = '.';
my $match = 'perl';

my @files = grep { -f } glob ( "$dir/*" );
for my $file(@files) {
    open my $fh, $file or next;
    print "Found match in $file\n" if grep{ /\Q$match\E/ }<$fh>;
}
[download]

cheers

tachyon

readdir returns the names of files, not their contents, so you're actually searching for files whose name matchs your keyword.