Well, it ain't off-the-shelf Perl. Maybe you mean something like:

use strict;
use warnings;

my $sitelist = xmlFileData ("Content", "Sitelist.txt");
my $Session;
my $str;

while (<$sitelist>) {
    chomp;
    next unless /\Q$Session->{'usrSystem'}\E/;
    $str .= MLX40Tutorials ();
}
[download]

However the code that you posted is so far from anything meaningful that it is pretty much impossible to decide just what you really want to happen.

I strongly recommend that you use strictures (use strict; use warnings;) which might at least make you focus a little on the scope of variables and where they get initialized.

Note that a straight character for character match is almost never what you want when processing XML. Perhaps you should tell us something about the bigger picture?

I want a line for line comparison with sitelist to match the session variable usrSystem, usrSystem will definitely already have a value, I am checking sitelist to see if it is in the list, if so then I want to do something branch to subroutine that displays newstuff for example, if not then I want to do something else ie old subroutine, with your snippet it looks like conditional would fall out of the loop if the session is not a match, am I reading that correctly? session is global, sitelist can be local. grandfather does this make more sense? I am really trying to clarify. Thanks

So write that up as a code snippet then we should be able to tell if it makes sense. Even better would be to mock up some data so that you can test the snippet is doing what you expect. Something like:

use strict;
use warnings;

my $sampleData = <<DATA;
this and that
wibble
the other
DATA

open my $sitelist, '<', \$sampleData;
my $Session = {usrSystem => 'wibble'};
my $str;

while (<$sitelist>) {
    chomp;
    if (/\Q$Session->{'usrSystem'}\E/) {
        print "New stuff for $_\n";
    } else {
        print "Something else for $_\n";
    }
}
[download]

Prints:

Something else for This and that
New stuff for wibble
Something else for the other
[download]

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