p4raw-id: //depot/perl@19164
If you want the old signal behaviour back regardless of possible
memory corruption, set the environment variable C<PERL_SIGNALS> to
-C<"unsafe">.
+C<"unsafe"> (a new feature since Perl 5.8.1).
=head1 Using open() for IPC
In Perls 5.8.1 and later. If set to C<unsafe> the pre-Perl-5.8.0
signals behaviour (immediate but unsafe) is restored. If set to
-C<safe> the safe signals are used.
+C<safe> the safe (or deferred) signals are used. See L<perlipc>.
=item PERL_UNICODE
See L<POSIX>.
+The delivery policy of signals changed in Perl 5.8.0 from immediate
+(also known as "unsafe") to deferred, also known as "safe signals".
+See L<perlipc> for more information.
+
Certain internal hooks can be also set using the %SIG hash. The
routine indicated by C<$SIG{__WARN__}> is called when a warning message is
about to be printed. The warning message is passed as the first