PERL_SIGNALS=unsafe enables the old unsafe/immediate signals.

p4raw-id: //depot/perl@18766

3 files changed, 15 insertions, 1 deletions

diff --git a/pod/perldiag.pod b/pod/perldiag.pod
index 8c59189c71..e64253e559 100644
--- a/pod/perldiag.pod
+++ b/pod/perldiag.pod
@@ -3427,6 +3427,10 @@ superfluous.
 (W signal) The signal handler named in %SIG doesn't, in fact, exist.
 Perhaps you put it into the wrong package?
 
+=item PERL_SIGNALS illegal: "%s"
+
+See L<perlrun/PERL_SIGNALS> for legal values.
+
 =item sort is now a reserved word
 
 (F) An ancient error message that almost nobody ever runs into anymore.
diff --git a/pod/perlipc.pod b/pod/perlipc.pod
index f55bdff505..b743d4df04 100644
--- a/pod/perlipc.pod
+++ b/pod/perlipc.pod
@@ -279,7 +279,7 @@ to find out whether anyone (or anything) has accidentally removed our fifo.
 	sleep 2;    # to avoid dup signals
     }
 
-=head2 Deferred Signals
+=head2 Deferred Signals (Safe signals)
 
 In Perls before Perl 5.7.3 by installing Perl code to deal with
 signals, you were exposing yourself to danger from two things.  First,
@@ -368,6 +368,10 @@ there are un-waited-for completed child processes.
 
 =back
 
+If you want the old signal behaviour back regardless of possible
+memory corruption, set the environment variable C<PERL_SIGNALS> to
+C<"unsafe">.
+
 =head1 Using open() for IPC
 
 Perl's basic open() statement can also be used for unidirectional
diff --git a/pod/perlrun.pod b/pod/perlrun.pod
index 0f5bd35ffd..b9adb9b5a0 100644
--- a/pod/perlrun.pod
+++ b/pod/perlrun.pod
@@ -1091,6 +1091,12 @@ affect perl on VMS include PERLSHR, PERL_ENV_TABLES, and
 SYS$TIMEZONE_DIFFERENTIAL but are optional and discussed further in
 L<perlvms> and in F<README.vms> in the Perl source distribution.
 
+=item PERL_SIGNALS
+
+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.
+
 =item PERL_UNICODE
 
 Equivalent to the B<-C> command-line switch.