$ perl -d ./aliasing2.pl

Loading DB routines from perl5db.pl version 1.28
Editor support available.

Enter h or `h h' for help, or `man perldebug' for more help.

main::(./aliasing2.pl:3):    my $file = "foo.out";
  DB<1> c
fds before aliasing: fh=8, STDOUT=1
fds after aliasing:  fh=8, STDOUT=8
Debugged program terminated.  Use q to quit or R to restart,
  use o inhibit_exit to avoid stopping after program termination,
  h q, h R or h o to get additional info.  
  DB<1> q