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 ae9e0c2..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 *
 
@@ -890,9 +922,9 @@ vmsperl on the web, http://www.sidhe.org/vmsperl/index.html
 
 =head2 VOS
 
-Perl on VOS is discussed in F<README.vos> in the perl distribution.
-Perl on VOS can accept either VOS- or Unix-style file
-specifications as in either of the following:
+Perl on VOS is discussed in F<README.vos> in the perl distribution
+(installed as L<perlvos>).  Perl on VOS can accept either VOS- or
+Unix-style file specifications as in either of the following:
 
     $ perl -ne "print if /perl_setup/i" >system>notices
     $ perl -ne "print if /perl_setup/i" /system/notices
@@ -908,12 +940,11 @@ contain a slash character cannot be processed.  Such files must be
 renamed before they can be processed by Perl.  Note that VOS limits
 file names to 32 or fewer characters.
 
-The following C functions are unimplemented on VOS, and any attempt by
-Perl to use them will result in a fatal error message and an immediate
-exit from Perl:  dup, do_aspawn, do_spawn, fork, waitpid.  Once these
-functions become available in the VOS POSIX.1 implementation, you can
-either recompile and rebind Perl, or you can download a newer port from
-ftp.stratus.com.
+See F<README.vos> for restrictions that apply when Perl is built
+with the alpha version of VOS POSIX.1 support.
+
+Perl on VOS is built without any extensions and does not support
+dynamic loading.
 
 The value of C<$^O> on VOS is "VOS".  To determine the architecture that
 you are running on without resorting to loading all of C<%Config> you
@@ -1044,7 +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 *
@@ -1056,7 +1087,7 @@ general usage issues for all EBCDIC Perls.  Send a message body of
 =item  *
 
 AS/400 Perl information at
-ttp://as400.rochester.ibm.com/
+http://as400.rochester.ibm.com/
 as well as on CPAN in the F<ports/> directory.
 
 =back
@@ -1203,7 +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 *
 
@@ -1211,7 +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>
 
@@ -1995,8 +2026,9 @@ http://www.perl.com/CPAN/ports/index.html for binary distributions.
 
 =head1 SEE ALSO
 
-L<perlamiga>, L<perlcygwin>, L<perldos>, L<perlhpux>, L<perlos2>,
-L<perlos390>, L<perlwin32>, L<perlvms>, and L<Win32>.
+L<perlaix>, L<perlamiga>, L<perlcygwin>, L<perldos>, L<perlepoc>,
+L<perlebcdic>, L<perlhpux>, L<perlos2>, L<perlos390>, L<perlbs2000>,
+L<perlwin32>, L<perlvms>, L<perlvos>, and L<Win32>.
 
 =head1 AUTHORS / CONTRIBUTORS
 
@@ -2012,7 +2044,7 @@ Neale Ferguson <neale@mailbox.tabnsw.com.au>,
 David J. Fiander <davidf@mks.com>,
 Paul Green <Paul_Green@stratus.com>,
 M.J.T. Guy <mjtg@cus.cam.ac.uk>,
-Jarkko Hietaniemi <jhi@iki.fi<gt>,
+Jarkko Hietaniemi <jhi@iki.fi>,
 Luther Huffman <lutherh@stratcom.com>,
 Nick Ing-Simmons <nick@ni-s.u-net.com>,
 Andreas J. KE<ouml>nig <koenig@kulturbox.de>,