Remove particular word in the starting of line

You just want to remove all lines that start with HPL_? That's easy!

perl -pi -e 's/^HPL_.*//s' myfile.txt



OR


#!perl

use strict;
use autodie;
use warnings FATAL => "all";

my $infile = "myfile.txt";
my $outfile = "changed.txt";

open( my $infh, '<', $infile );
open( my $outfh, '>', $outfile );
while( my $line = <$infh> ) {
   next if $line =~ /^HPL_/;
   print $outfh $line;
}
close( $outfh );
close( $infh );



OR


#!/usr/bin/perl
use strict;
use warnings;

open(my $in, '<', 'myfile.txt') or die "failed to open input for read: $!";
my @lines = <$in> or die 'no lines to read from input';
close($in);

# collect all lines that do not begin with HPL_ into @result
my @result = grep ! /^HPL_/, @lines;

open(my $out, '>', 'changed.txt') or die "failed to open output for write: $!";
print { $out } @result;
close($out);