#!perl -w

use strict;
use warnings;

sub see_args { 
    printf "I see args '%s'\n", join("', '",@_); 
    return; 
}

    warn sprintf "In test, at start (1): TMPDIR '%s'\n",
        ! exists $ENV{TMPDIR} ?  '<absent>' : ! defined $ENV{TMPDIR} ? '<undef>' : $ENV{TMPDIR};

    see_args( @ENV{qw(TMPDIR TEMP TMP)} );

    warn sprintf "In test, at end (2): TMPDIR '%s'\n",
        ! exists $ENV{TMPDIR} ?  '<absent>' : ! defined $ENV{TMPDIR} ? '<undef>' : $ENV{TMPDIR};

##</code><code>##

In test, at start (1): TMPDIR '<absent>'
Use of uninitialized value in join or string at test3.pl line 7.
I see args '', 'C:\DOCUME~1\ADMINI~1\LOCALS~1\Temp', 'C:\DOCUME~1\ADMINI~1\LOCALS~1\Temp'
In test, at end (2): TMPDIR '<undef>'

##</code><code>##

In test, at start (1): TMPDIR '<absent>'
In test, at end (2): TMPDIR '<undef>'