use strict;

my $filename = '/home/cgmd/bin/learning_perl/sample_text';
open FILE, $filename
   or die "Can't open '$filename': $!";
chomp(my @strings = <FILE>);
print "Please enter a pattern: ";
while ((my $pattern = <STDIN>)!~/^\s$/) {
  chomp $pattern;
  my @matches = eval {
    grep /$pattern/, @strings;
  };
  if ($@) {
    print "Error: $@";
  } else {
    my $count = @matches;
    print "There were $count matching strings:\n",
      map "$_\n", @matches;
    print "Please enter a pattern: ";
  }
   print "\n";
}
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In this version the while condition is not infinite, it breaks when the input pattern is empty.

citromatik