my $replacestring = "TOM";
open(my $infile,"<","inputfile.txt") or die $!;
open (my $outfile,">","outputfile.txt") or die $!;
while (<$infile>)
{
    $_=~s/$replacestring//g;
    print $outfile $_;
}
close $infile;
close $outfile;

##</code><code>##

my $string = "TOM";
open(my $infile,"<","inputfile.txt") or die $!;
open (my $outfile,">","outputfile.txt") or die $!;
while (<$infile>)
{
    if ($_ !~/$string/)
    {
       print $outfile $_;
    }
}
close $infile;
close $outfile;