open my $IN, "<", $infile
|| croak( "Could not open file $infile: $EXTENDED_OS_ERROR" );

open my $OUT, ">", $outfile
|| croak( "Could not open file $outfile: $EXTENDED_OS_ERROR" );

while ( <$IN> ){
  my $line = $_;
  chomp $line;
  if ( $line !~ /^AB.*C$/ ){
    print $OUT $line . "\n";
  }
}
close $IN;
close $OUT;