-T $file || -B $file
defined -T $file
defined -B $file

##</code><code>##

#!perl -l
use warnings;

print "-f:";
-f '""'
  ? print "Returned True (unwanted behaviour)\n"
  : print "Returned False (wanted behaviour)\n";

print "defined -f:";        
defined -f '""'
  ? print "Returned True (unwanted behaviour)\n"
  : print "Returned False (wanted behaviour)\n";

print "-T || -B:";
(-T '""' || -B '""')
  ? print "Returned True (unwanted behaviour)\n"
  : print "Returned False (wanted behaviour)\n";

print "defined -T:";
defined -T '""'
  ? print "Returned True (unwanted behaviour)\n"
  : print "Returned False (wanted behaviour)\n";

print "defined -B:";
defined -B '""'
  ? print "Returned True (unwanted behaviour)\n"
  : print "Returned False (wanted behaviour)\n";

##</code><code>##

-f:
Returned False (wanted behaviour)

defined -f:
Returned True (unwanted behaviour)

-T || -B:
Returned False (wanted behaviour)

defined -T:
Returned False (wanted behaviour)

defined -B:
Returned False (wanted behaviour)