source: vendor/perl/5.8.8/t/io/nargv.t

#!./perl

print "1..5\n";

my $j = 1;
for $i ( 1,2,5,4,3 ) {
    $file = mkfiles($i);
    open(FH, "> $file") || die "can't create $file: $!";
    print FH "not ok " . $j++ . "\n";
    close(FH) || die "Can't close $file: $!";
}


{
    local *ARGV;
    local $^I = '.bak';
    local $_;
    @ARGV = mkfiles(1..3);
    $n = 0;
    while (<>) {
        print STDOUT "# initial \@ARGV: [@ARGV]\n";
        if ($n++ == 2) {
            other();
        }
        show();
    }
}

$^I = undef;
@ARGV = mkfiles(1..3);
$n = 0;
while (<>) {
    print STDOUT "#final \@ARGV: [@ARGV]\n";
    if ($n++ == 2) {
        other();
    }
    show();
}

sub show {
    #warn "$ARGV: $_";
    s/^not //;
    print;
}

sub other {
    print STDOUT "# Calling other\n";
    local *ARGV;
    local *ARGVOUT;
    local $_;
    @ARGV = mkfiles(5, 4);
    while (<>) {
        print STDOUT "# inner \@ARGV: [@ARGV]\n";
        show();
    }
}

sub mkfiles {
    my @files = map { "scratch$_" } @_;
    return wantarray ? @files : $files[-1];
}

END { unlink map { ($_, "$_.bak") } mkfiles(1..5) }