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in reply to =~ matches non-existent symbols

Another way could be to use Tie::File and grep. 

use strict;
use warnings;

use Tie::File;

die "File does not exist" unless -f $ARGV[0];

tie my @file, 'Tie::File', $ARGV[0] or die "Could not tie file";

if ( grep !/^[actg]+$/i, @file )
{
        print "BAD\n";
}
else
{
        print "OK\n";
}

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Update: Inefficent see below update by ikegami

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Re^2: =~ matches non-existent symbols
by ikegami (Patriarch) on Nov 18, 2014 at 17:38 UTC
    What a waste. This will slow down the program by so much and it'll use up so much more memory than needed. You could simply use 
    use strict;
use warnings;

my $bad = 0;
while (<>) {
   if (!/^[actg]+$/i) {
      ++$bad;
      last;
   }
}

print $bad ? "BAD\n" : "OK\n";

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[reply]
[d/l]

      You are correct, I had not considered how inefficent that method is. Thanks for pointing it out.

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