Add more known sprintf failures.

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

diff --git a/pod/perlport.pod b/pod/perlport.pod
index d1887bf..457584c 100644 (file)
--- a/pod/perlport.pod
+++ b/pod/perlport.pod
@@ -94,6 +94,26 @@ from) C<\015\012>, depending on whether you're reading or writing.
 Unix does the same thing on ttys in canonical mode.  C<\015\012>
 is commonly referred to as CRLF.
 
+A common cause of unportable programs is the misuse of chop() to trim
+newlines:
+
+    # XXX UNPORTABLE!
+    while(<FILE>) {
+        chop;
+        @array = split(/:/);
+        #...
+    }
+
+You can get away with this on Unix and MacOS (they have a single
+character end-of-line), but the same program will break under DOSish
+perls because you're only chop()ing half the end-of-line.  Instead,
+chomp() should be used to trim newlines.  The Dunce::Files module can
+help audit your code for misuses of chop().
+
+When dealing with binary files (or text files in binary mode) be sure
+to explicitly set $/ to the appropriate value for your file format
+before using chomp().
+
 Because of the "text" mode translation, DOSish perls have limitations
 in using C<seek> and C<tell> on a file accessed in "text" mode.
 Stick to C<seek>-ing to locations you got from C<tell> (and no
@@ -334,7 +354,10 @@ operating systems put mandatory locks on such files.
 
 Don't count on a specific environment variable existing in C<%ENV>.
 Don't count on C<%ENV> entries being case-sensitive, or even
-case-preserving.
+case-preserving.  Don't try to clear %ENV by saying C<%ENV = ();>, or,
+if you really have to, make it conditional on C<$^O ne 'VMS'> since in
+VMS the C<%ENV> table is much more than a per-process key-value string
+table.
 
 Don't count on signals or C<%SIG> for anything.
 
@@ -652,6 +675,15 @@ DOSish perls are as follows:
     Windows NT    MSWin32    MSWin32-ppc
     Cygwin        cygwin
 
+The various MSWin32 Perl's can distinguish the OS they are running on
+via the value of the fifth element of the list returned from 
+Win32::GetOSVersion().  For example:
+
+    if ($^O eq 'MSWin32') {
+        my @os_version_info = Win32::GetOSVersion();
+        print +('3.1','95','NT')[$os_version_info[4]],"\n";
+    }
+
 Also see:
 
 =over 4
@@ -683,7 +715,7 @@ The ActiveState Pages, http://www.activestate.com/
 =item *
 
 The Cygwin environment for Win32; F<README.cygwin> (installed 
-as L<perlcygwin>), http://sources.redhat.com/cygwin/
+as L<perlcygwin>), http://www.cygwin.com/
 
 =item *
 
@@ -1043,7 +1075,7 @@ Also see:
 
 *
 
-L<perlos390>, F<README.os390>, F<perlposix-bc>, F<README.vmesa>,
+L<perlos390>, F<README.os390>, F<perlbs2000>, F<README.vmesa>,
 L<perlebcdic>.
 
 =item *
@@ -1202,7 +1234,7 @@ Be OS, F<README.beos>
 =item *
 
 HP 300 MPE/iX, F<README.mpeix> and Mark Bixby's web page
-http://www.cccd.edu/~markb/perlix.html
+http://www.bixby.org/mark/perlix.html
 
 =item *
 
@@ -1210,7 +1242,7 @@ A free perl5-based PERL.NLM for Novell Netware is available in
 precompiled binary and source code form from http://www.novell.com/
 as well as from CPAN.
 
-=item 
+=item  *
 
 Plan 9, F<README.plan9>
 
@@ -1995,7 +2027,7 @@ http://www.perl.com/CPAN/ports/index.html for binary distributions.
 =head1 SEE ALSO
 
 L<perlaix>, L<perlamiga>, L<perlcygwin>, L<perldos>, L<perlepoc>,
-L<perlebcdic>, L<perlhpux>, L<perlos2>, L<perlos390>, L<perlposix-bc>,
+L<perlebcdic>, L<perlhpux>, L<perlos2>, L<perlos390>, L<perlbs2000>,
 L<perlwin32>, L<perlvms>, L<perlvos>, and L<Win32>.
 
 =head1 AUTHORS / CONTRIBUTORS