#! /usr/bin/perl
use v5.16;
use warnings;

##############
##  03/14/19
##  Exercise reads from file, then lets user interactively submit matching search criteria

    my $input_file = <STDIN>;
    open my $fh, '<', $input_file;
    chomp(my @strings = <$fh>); 
    while (1) {
       print 'Please enter a pattern: ';
       chomp(my $pattern = <STDIN>);
       last if $pattern =~ /\A\s*\Z/;
       my @matches = eval { 
          grep /$pattern/, @strings;
       }; ## end of eval
       if ($@) {
          print "Error: $@";
       } else {
           my $count = @matches;
           print "There were $count matching strings:\n",
             map "$_\n", @matches;
       }
       print "\n";
     }

readline() on closed filehandle $fh at ./Chapter16_Exer1 line 11.