C:\>perl -d -Te"warn 1; warn fileno shift" -

Loading DB routines from perl5db.pl version 1.3
Editor support available.

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

main::(-e:1):   warn 1; warn fileno shift
  DB<1> n
1 at -e line 1.
 at -e line 1
main::(-e:1):   warn 1; warn fileno shift
  DB<1> n
Warning: something's wrong at -e line 1.
 at -e line 1
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> n
Use `q' to quit or `R' to restart.  `h q' for details.
  DB<1>
Use `q' to quit or `R' to restart.  `h q' for details.
  DB<1> q

C:\>