$^S

Current state of the interpreter.

    $^S         State
    ---------   -------------------
    undef       Parsing module/eval
    true (1)    Executing an eval
    false (0)   Otherwise

The first state may happen in $SIG{__DIE__} and $SIG{__WARN__} handlers.

##</code><code>##

#!/usr/bin/perl
use strict;
use warnings;

close STDERR;
$|++;
my $contaerrori= 0;
$SIG{__WARN__} = sub { ++$contaerrori;print STDOUT "[WARN] ",@_ };
$SIG{__DIE__} = sub  {
                        print STDOUT "[CRITICAL ERROR]\t",@_;
                        if  ($^S == 1) { print  "\tPerl interpreter     1 (Executing an eval)\n\tCONTINUE RUNNING\n"}
                        elsif ($^S == 0){ print "\tPerl interpreter     0 (Otherwise)\n\tSTOP\n"}
                        else { print            "\tPerl interpreter undef (Parsing module/eval)\n"}
                        print "\n";
                        };
################################################################################
# HERE THE TESTS
################################################################################

print "\nNATURAL END OF PROGRAM : ",$contaerrori," WARN",($contaerrori eq 1 ? '' : 'S' )," IN $0\n";


##</code><code>##

#A
print $a."\n";
#B
require AAAAAA;
#C
eval { require BBBBB; } or do { warn "  cannot load the mobule BBBBB \$^S = $^S\n";
                                print "\ttrying with another module: CCCC\n\n";
                                eval { require CCCC; } or do {warn "cannot load the mobule CCCC \$^S = $^S\n";};
                                if ( $@ ) {warn "no hope with modules today..\n\n";die}
                                else {print "\tsuccesfully loaded CCCC\n" ;}

                                };
#D
eval { 0 } or do { warn "zero is not true \$^S = $^S\n"; };
#E
eval { undef } or die "undef is not enough \$^S = $^S\n";
#F
eval {require AAAAAA;};
if ($@) {
        local $SIG{'__DIE__'} = 'DEFAULT';
        die "default die : $@";
}

##</code><code>##

#A
[WARN] Use of uninitialized value in concatenation (.) or string at warn-die.pl line 18.

NATURAL END OF PROGRAM : 1 WARN IN warn-die.pl
#B
[CRITICAL ERROR]	Can't locate AAAAAA.pm in @INC (@INC contains: C:/Perl/site/lib C:/Perl/lib .) at warn-die.pl line 20.
	Perl interpreter     0 (Otherwise)
	STOP
#C
[CRITICAL ERROR]	Can't locate BBBBB.pm in @INC (@INC contains: C:/Perl/site/lib C:/Perl/lib .) at warn-die.pl line 21.
	Perl interpreter     1 (Executing an eval)
	CONTINUE RUNNING

[WARN]   cannot load the mobule BBBBB $^S = 0
	trying with another module: CCCC

[CRITICAL ERROR]	Can't locate CCCC.pm in @INC (@INC contains: C:/Perl/site/lib C:/Perl/lib .) at warn-die.pl line 23.
	Perl interpreter     1 (Executing an eval)
	CONTINUE RUNNING

[WARN] cannot load the mobule CCCC $^S = 0
[WARN] no hope with modules today..

[CRITICAL ERROR]	Can't locate CCCC.pm in @INC (@INC contains: C:/Perl/site/lib C:/Perl/lib .) at warn-die.pl line 23.
	...propagated at warn-die.pl line 24.
	Perl interpreter     0 (Otherwise)
	STOP
#D
[WARN] zero is not true $^S = 0
NATURAL END OF PROGRAM : 1 WARN IN warn-die.pl
#E
[CRITICAL ERROR] undef is not enough $^S = 0
	Perl interpreter     0 (Otherwise)
	STOP
#F
[CRITICAL ERROR]Can't locate AAAAAA.pm in @INC (@INC contains: C:/Perl/site/lib C:/Perl/lib .) at warn-die.pl line 25.
	Perl interpreter     1 (Executing an eval)
	CONTINUE RUNNING