More $0 sad tales.

[p5sagit/p5-mst-13.2.git] / pod / perlvar.pod

diff --git a/pod/perlvar.pod b/pod/perlvar.pod
index a4e8895..43e1468 100644 (file)
--- a/pod/perlvar.pod
+++ b/pod/perlvar.pod
@@ -294,26 +294,6 @@ past where $2 ends, and so on.  You can use C<$#+> to determine
 how many subgroups were in the last successful match.  See the
 examples given for the C<@-> variable.
 
-=item $MULTILINE_MATCHING
-
-=item $*
-
-Set to a non-zero integer value to do multi-line matching within a
-string, 0 (or undefined) to tell Perl that it can assume that strings
-contain a single line, for the purpose of optimizing pattern matches.
-Pattern matches on strings containing multiple newlines can produce
-confusing results when C<$*> is 0 or undefined. Default is undefined.
-(Mnemonic: * matches multiple things.) This variable influences the
-interpretation of only C<^> and C<$>. A literal newline can be searched
-for even when C<$* == 0>.
-
-Use of C<$*> is deprecated in modern Perl, supplanted by 
-the C</s> and C</m> modifiers on pattern matching.
-
-Assigning a non-numerical value to C<$*> triggers a warning (and makes
-C<$*> act if C<$* == 0>), while assigning a numerical value to C<$*>
-makes that an implicit C<int> is applied on the value.
-
 =item HANDLE->input_line_number(EXPR)
 
 =item $INPUT_LINE_NUMBER
@@ -858,20 +838,35 @@ and C<$)> can be swapped only on machines supporting setregid().
 
 =item $0
 
-Contains the name of the program being executed.  On some operating
-systems assigning to C<$0> modifies the argument area that the B<ps>
-program sees.  This is more useful as a way of indicating the current
-program state than it is for hiding the program you're running.
-(Mnemonic: same as B<sh> and B<ksh>.)
+Contains the name of the program being executed.
+
+On some (read: not all) operating systems assigning to C<$0> modifies
+the argument area that the C<ps> program sees.  On some platforms you
+may have to use special C<ps> options or a different C<ps> to see the
+changes.  Modifying the $0 is more useful as a way of indicating the
+current program state than it is for hiding the program you're
+running.  (Mnemonic: same as B<sh> and B<ksh>.)
+
+Note that there are platform specific limitations on the the maximum
+length of C<$0>.  In the most extreme case it may be limited to the
+space occupied by the original C<$0>.
+
+In some platforms there may be arbitrary amount of padding, for
+example space characters, after the modified name as shown by C<ps>.
+In some platforms this padding may extend all the way to the original
+length of the argument area, no matter what you do.
 
 Note for BSD users: setting C<$0> does not completely remove "perl"
-from the ps(1) output.  For example, setting C<$0> to C<"foobar"> will
-result in C<"perl: foobar (perl)">.  This is an operating system
-feature.
+from the ps(1) output.  For example, setting C<$0> to C<"foobar"> may
+result in C<"perl: foobar (perl)"> (whether both the C<"perl: "> prefix
+and the " (perl)" suffix are shown depends on your exact BSD variant
+and version).  This is an operating system feature, Perl cannot help it.
 
 In multithreaded scripts Perl coordinates the threads so that any
 thread may modify its copy of the C<$0> and the change becomes visible
-to ps(1) (assuming the operating system plays along).
+to ps(1) (assuming the operating system plays along).  Note that the
+the view of C<$0> the other threads have will not change since they
+have their own copies of it.
 
 =item $[
 
@@ -883,8 +878,14 @@ subscripting and when evaluating the index() and substr() functions.
 
 As of release 5 of Perl, assignment to C<$[> is treated as a compiler
 directive, and cannot influence the behavior of any other file.
+(That's why you can only assign compile-time constants to it.)
 Its use is highly discouraged.
 
+Note that, unlike other compile-time directives (such as L<strict>),
+assignment to $[ can be seen from outer lexical scopes in the same file.
+However, you can use local() on it to strictly bound its value to a
+lexical block.
+
 =item $]
 
 The version + patchlevel / 1000 of the Perl interpreter.  This variable
@@ -916,7 +917,8 @@ C<$^C = 1> is similar to calling C<B::minus_c>.
 =item $^D
 
 The current value of the debugging flags.  (Mnemonic: value of B<-D>
-switch.)
+switch.) May be read or set. Like its command-line equivalent, you can use
+numeric or symbolic values, eg C<$^D = 10> or C<$^D = "st">.
 
 =item $SYSTEM_FD_MAX
 
@@ -1117,9 +1119,10 @@ B<-t> or B<-TU>).  This variable is read-only.
 
 =item ${^UNICODE}
 
-Reflects certain Unicode settings of Perl.  See L<perlrun> for more
-information about the possible values. This variable is set during
-Perl startup and thereafter read-only.
+Reflects certain Unicode settings of Perl.  See L<perlrun>
+documentation for the C<-C> switch for more information about
+the possible values. This variable is set during Perl startup
+and is thereafter read-only.
 
 =item $PERL_VERSION
 
@@ -1343,6 +1346,10 @@ this:
 
 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