$ perl -d -e 1

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::(-e:1):   1
Can't ioctl TIOCGETP: Invalid argument
Consider installing Term::ReadKey from CPAN site nearby
        at http://www.perl.com/CPAN
Or use
        perl -MCPAN -e shell
to reach CPAN. Falling back to 'stty'.
        If you do not want to see this warning, set PERL_READLINE_NOWARN