I suspect it may be that you are not actually writing the session file, probably due to File::Spec::tmpdir returning a dir you can't write. CGI::Session fails silently in this case. Try adding END{ warn $session->error } to pick up any errors.

You are making harder work of it than required. Try something like this with a hard coded tmpdir file. CHECK to see that your session files are getting written there.

my $q = CGI->new;

# this will return a session object.
# if the CGISESSID is avialable via cookie or param 
# that is what's used, otherwise it is a new session

my $session = new CGI::Session("driver:File", $q, {Directory=>'/tmp'})
+;

# this prints a header with the CGISSESSID cookie:
print $session->header()

# now if you want to stick it in a form as well, get the SESSID
my $sessid = $session->id;

# and stick it in the form.....
print <<HTML;
<form>
<input type="hidden" name="CGISESSID" value="$sessid">
</form>
HTML
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