Make using U+FDD0..U+FDEF (noncharacters since Unicode 3.1),

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

diff --git a/pod/perlrun.pod b/pod/perlrun.pod
index 0e3017f..2b7cca1 100644 (file)
--- a/pod/perlrun.pod
+++ b/pod/perlrun.pod
@@ -4,7 +4,7 @@ perlrun - how to execute the Perl interpreter
 
 =head1 SYNOPSIS
 
-B<perl>        S<[ B<-CsTuUWX> ]>
+B<perl>        S<[ B<-CsTtuUWX> ]>
        S<[ B<-hv> ] [ B<-V>[:I<configvar>] ]>
        S<[ B<-cw> ] [ B<-d>[:I<debugger>] ] [ B<-D>[I<number/list>] ]>
        S<[ B<-pna> ] [ B<-F>I<pattern> ] [ B<-l>[I<octal>] ] [ B<-0>[I<octal>] ]>
@@ -569,12 +569,39 @@ the implicit loop, just as in B<awk>.
 
 =item B<-P>
 
-causes your program to be run through the C preprocessor before
+B<NOTE: Use of -P is strongly discouraged because of its inherent
+problems, including poor portability.>
+
+This option causes your program to be run through the C preprocessor before
 compilation by Perl.  Because both comments and B<cpp> directives begin
 with the # character, you should avoid starting comments with any words
 recognized by the C preprocessor such as C<"if">, C<"else">, or C<"define">.
-Also, in some platforms the C preprocessor knows too much: it knows
-about the C++ -style until-end-of-line comments starting with C<"//">.
+
+If you're considering using C<-P>, you might also want to look at the
+Filter::cpp module from CPAN.
+
+The problems of -P include, but are not limited to:
+
+=over 10
+
+=item *
+
+The C<#!> line is stripped, so any switches there don't apply.
+
+=item *
+
+A C<-P> on a C<#!> line doesn't work.
+
+=item *
+
+B<All> lines that begin with (whitespace and) a C<#> but
+do not look like cpp commands, are stripped, including anything
+inside Perl strings, regular expressions, and here-docs . 
+
+=item *
+
+In some platforms the C preprocessor knows too much: it knows about
+the C++ -style until-end-of-line comments starting with C<"//">.
 This will cause problems with common Perl constructs like
 
     s/foo//;
@@ -588,6 +615,23 @@ like for example C<"!">:
 
     s!foo!!;
 
+
+
+=item *
+
+It requires not only a working C preprocessor but also a working
+F<sed>.  If not on UNIX, you are probably out of luck on this.
+
+=item *
+
+Script line numbers are not preserved.
+
+=item *
+
+The C<-x> does not work with C<-P>.
+
+=back
+
 =item B<-s>
 
 enables rudimentary switch parsing for switches on the command
@@ -653,6 +697,15 @@ separators, it will first be searched for in the current directory
 before being searched for on the PATH.  On Unix platforms, the
 program will be searched for strictly on the PATH.
 
+=item B<-t>
+
+Like B<-T>, but taint checks will issue warnings rather than fatal
+errors.  Since these are warnings, the B<-w> switch (or C<use
+warnings>) must be used along with this option.  B<NOTE: this is
+not a substitute for -T.> This is meant only to be used as a temporary
+aid while securing legacy code: for real production code and for new
+secure code written from scratch always use the real B<-T>.
+
 =item B<-T>
 
 forces "taint" checks to be turned on so you can test them.  Ordinarily
@@ -785,7 +838,7 @@ The program should instead say:
 =item PERL5OPT
 
 Command-line options (switches).  Switches in this variable are taken
-as if they were on every Perl command line.  Only the B<-[DIMUdmw]>
+as if they were on every Perl command line.  Only the B<-[DIMUdmtw]>
 switches are allowed.  When running taint checks (because the program
 was running setuid or setgid, or the B<-T> switch was used), this
 variable is ignored.  If PERL5OPT begins with B<-T>, tainting will be