use IO::File;
use strict;

# Load host list
my $host = new IO::File "host.txt", "r"
    or die "Can not open host list file!";
my @hosts = <$host>;
undef $host;
foreach (@hosts) {
    chomp;
    s/\s+//g;   # get rid of spaces
}

# Load input lines
my $input = new IO::File "mainfile.txt", "r"
    or die "Can not open file!";
my @lines = <$input>;
undef $input;
foreach (@lines) { chomp };

# Create output files for hosts
my $prefix = "mainfile_";
foreach (@hosts)
{
    my ($hostname, $ipaddr) = split/,/;
    
    # Create the output file, and replace the
    # HOST and IP lines with actual data
    my $output = new IO::File "${prefix}${hostname}.txt", "w"
        or die "Can not create file!";
        
    foreach my $txt (@lines)
    {
        if ($txt eq "HOST") {
            print $output "$hostname\n";
        } elsif ($txt eq "IP") {
            print $output "$ipaddr\n";
        } else {
            print $output "$txt\n";
        }           
    }
    
    # explicitly close the output file
    # not required, but good for the eye
    undef $output;
}
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Thanky very much for the quick answer.
The code works great!.
I have only one more question.
If the "MAINFILE.TXT" also contain the HOST and IP on several lines like this.
"MAINFILE.TXT"
someinfo
HOST
IP
someinfo
This is my computer HOST and it has the adress IP.
someinfo someinfoHOSTsomeinfo
How can I also replace these?.

Yes It it should be one line
someinfo someinfoHOSTsomeinfo


//Anders Andersson

If you want to replace all occurances of HOST and IP in your mainfile.txt during the copy process, you just need to replace the printing part:



 ...

 foreach my $txt (@lines)
 {
   # replace HOST and IP with $hostname and $ipaddr
   $txt =~ s/HOST/$hostname/g;
   $txt =~ s/IP/$ipaddr/g;
   print $output "$txt\n";
 }
[download]

This will replace ALL occurances of HOST and IP in your mainfile.txt.

Isn't Getopt::Long part of the core distribution? I don't remember installing it on my machine and it's there. Then again, it could just be that my brain needs to be upgraded.

You are probably right. I just mentioned CPAN because in case a certain module is not found, you know where to get it. :-)

Warning:The following script is based on your first definition of HOSTS.TXT. You would have to use a split or other means to extract the host name if your HOSTS.TXT is actually as in your second definition.

In fact the second part is rather unclear - perhaps you could provide an exact explanation of what is in your files and what you wish to achieve?

#!/usr/bin/perl -w
use strict;
use CGI::Carp qw(fatalsToBrowser warningsToBrowser);
use CGI ':standard';


open MAINFILE, "../test/MAINFILE.TXT" or die $!;
my @all = <MAINFILE>;
close MAINFILE;

open HOST, "../test/HOSTS.TXT" or die $!;
foreach my $line (<HOST>) {
    chomp $line;
    open HOSTFILE, "> ../test/results/MAINFILE_$line.txt" or die $!;
    print HOSTFILE "@all";
    close HOSTFILE;
}
close HOST;    


print "Content-type: text/html\n\n";
print "done";
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