Here's a simple example script.

#!/usr/bin/perl -w
use strict;

# make html/forms easy to deal with
use CGI;

# report errors in the browser
# (remove from production code)
use CGI::Carp 'fatalsToBrowser';

# create new CGI object
my $q = new CGI;

if ( ! $q->param() )
{
    # first run, so present form
    print
        $q->header,
        $q->start_html,
        $q->start_multipart_form,
        $q->filefield('file'),
        $q->br,
        $q->submit('Upload'),
        $q->end_form,
        $q->end_html;
}
else
{
    # file uploaded, so process it

    # read filehandle from param and set to binary mode
    my $filehandle = $q->param('file');
    binmode $filehandle;

    # open file for output. Change this to suit your needs!!!
    open OUT, "> /path/to/local/filename" or die $!;
    binmode OUT;

    # process $filehandle
    {
        my $buffer;
        while ( read $filehandle, $buffer, 1024 )
        { 
            print OUT $buffer;
        }
    }

    close OUT;

    # show success
    print
        $q->header,
        $q->start_html,
        $q->p('File uploaded'),
        $q->end_html;
}
[download]

$SIG{__DIE__} = \&my_die;

use CGI;

$C = new CGI;
if ($C->param) {

$file=$C->param("upload");
### if you need to do fancy placement look at
### File::Basename
open (UPLOAD, "/path/to/file");

while ($bytesread=read($file,$buffer,1024)) {
    print UPLOAD $buffer;
}

print $C->header;
print $C->start_html;
print qq(<p>file uploaded successfully</p>);
print $C->end_html;
exit;
}
else
{
print $C->header;
print $C->start_html;
print $C->start_multipart_form;
print $C->filefield(-name=>'file');
print qq(<input type="submit" name="submit" value="submit">
    </form>
);
print $C->end_html;
exit;
}


sub my_die {

print $C->header;
print $C->start_html;
print $_;
print $C->end_html;
}
[download]

Originally posted as a Categorized Answer.