transient information about idiosyncrasies of some of the ports, almost
all of which are in a state of constant evolution. Thus, this material
should be considered a perpetual work in progress
-(<IMG SRC="yellow_sign.gif" ALT="Under Construction">).
+(C<< <IMG SRC="yellow_sign.gif" ALT="Under Construction"> >>).
=head1 ISSUES
Some of this may be confusing. Here's a handy reference to the ASCII CR
and LF characters. You can print it out and stick it in your wallet.
- LF == \012 == \x0A == \cJ == ASCII 10
- CR == \015 == \x0D == \cM == ASCII 13
+ LF eq \012 eq \x0A eq \cJ eq chr(10) eq ASCII 10
+ CR eq \015 eq \x0D eq \cM eq chr(13) eq ASCII 13
| Unix | DOS | Mac |
---------------------------
"\n", and "\n" on output becomes CRLF.
These are just the most common definitions of C<\n> and C<\r> in Perl.
-There may well be others.
+There may well be others. For example, on an EBCDIC implementation such
+as z/OS or OS/400 the above material is similar to "Unix" but the code
+numbers change:
+
+ LF eq \025 eq \x15 eq chr(21) eq CP-1047 21
+ LF eq \045 eq \x25 eq \cU eq chr(37) eq CP-0037 37
+ CR eq \015 eq \x0D eq \cM eq chr(13) eq CP-1047 13
+ CR eq \015 eq \x0D eq \cM eq chr(13) eq CP-0037 13
+
+ | z/OS | OS/400 |
+ ----------------------
+ \n | LF | LF |
+ \r | CR | CR |
+ \n * | LF | LF |
+ \r * | CR | CR |
+ ----------------------
+ * text-mode STDIO
=head2 Numbers endianness and Width
the standard distribution as of Perl 5.005) and Storable (included as
of perl 5.8). Keeping all data as text significantly simplifies matters.
+The v-strings are portable only up to v2147483647 (0x7FFFFFFF), that's
+how far EBCDIC, or more precisely UTF-EBCDIC will go.
+
=head2 Files and Filesystems
Most platforms these days structure files in a hierarchical fashion.
modification timestamp), or one second granularity of any timestamps
(e.g. the FAT filesystem limits the time granularity to two seconds).
+The "inode change timestamp" (the C<-C> filetest) may really be the
+"creation timestamp" (which it is not in UNIX).
+
VOS perl can emulate Unix filenames with C</> as path separator. The
native pathname characters greater-than, less-than, number-sign, and
percent-sign are always accepted.
Don't assume a text file will end with a newline. They should,
but people forget.
-Do not have two files of the same name with different case, like
-F<test.pl> and F<Test.pl>, as many platforms have case-insensitive
-filenames. Also, try not to have non-word characters (except for C<.>)
-in the names, and keep them to the 8.3 convention, for maximum
-portability, onerous a burden though this may appear.
+Do not have two files or directories of the same name with different
+case, like F<test.pl> and F<Test.pl>, as many platforms have
+case-insensitive (or at least case-forgiving) filenames. Also, try
+not to have non-word characters (except for C<.>) in the names, and
+keep them to the 8.3 convention, for maximum portability, onerous a
+burden though this may appear.
Likewise, when using the AutoSplit module, try to keep your functions to
8.3 naming and case-insensitive conventions; or, at the least,
make it so the resulting files have a unique (case-insensitively)
first 8 characters.
-Whitespace in filenames is tolerated on most systems, but not all.
+Whitespace in filenames is tolerated on most systems, but not all,
+and even on systems where it might be tolerated, some utilities
+might become confused by such whitespace.
+
Many systems (DOS, VMS) cannot have more than one C<.> in their filenames.
Don't assume C<< > >> won't be the first character of a filename.
-Always use C<< < >> explicitly to open a file for reading,
-unless you want the user to be able to specify a pipe open.
+Always use C<< < >> explicitly to open a file for reading, or even
+better, use the three-arg version of open, unless you want the user to
+be able to specify a pipe open.
- open(FILE, "< $existing_file") or die $!;
+ open(FILE, '<', $existing_file) or die $!;
If filenames might use strange characters, it is safest to open it
with C<sysopen> instead of C<open>. C<open> is magic and can
translate characters like C<< > >>, C<< < >>, and C<|>, which may
be the wrong thing to do. (Sometimes, though, it's the right thing.)
+Three-arg open can also help protect against this translation in cases
+where it is undesirable.
+
+Don't use C<:> as a part of a filename since many systems use that for
+their own semantics (MacOS Classic for separating pathname components,
+many networking schemes and utilities for separating the nodename and
+the pathname, and so on). For the same reasons, avoid C<@>, C<;> and
+C<|>.
+
+Don't assume that in pathnames you can collapse two leading slashes
+C<//> into one: some networking and clustering filesystems have special
+semantics for that. Let the operating system to sort it out.
+
+The I<portable filename characters> as defined by ANSI C are
+
+ a b c d e f g h i j k l m n o p q r t u v w x y z
+ A B C D E F G H I J K L M N O P Q R T U V W X Y Z
+ 0 1 2 3 4 5 6 7 8 9
+ . _ -
+
+and the "-" shouldn't be the first character. If you want to be
+hypercorrect, stay case-insensitive and within the 8.3 naming
+convention (all the files and directories have to be unique within one
+directory if their names are lowercased and truncated to eight
+characters before the C<.>, if any, and to three characters after the
+C<.>, if any). (And do not use C<.>s in directory names.)
=head2 System Interaction
Don't count on specific values of C<$!>.
+=head2 Command names versus file pathnames
+
+Don't assume that the name used to invoke a command or program with
+C<system> or C<exec> can also be used to test for the existence of the
+file that holds the executable code for that command or program.
+First, many operating systems have "internal" commands that are
+built-in to the OS and while these commands can be invoked, there is
+no corresponding file. Second, some operating systems (Cygwin, DJGPP,
+OS/2, and VOS) have required suffixes for executable files; these
+suffixes are generally permitted on the command name but are not
+required. Thus, a command like "perl" might exist in a file named
+"perl", "perl.exe", or "perl.pm", depending on the operating system.
+The variable "_exe" in the Config module holds the executable suffix,
+if any. Third, VMS files always end in a version number, which comes
+after the executable suffix.
+
+To convert $^X to a file pathname, taking account of the requirements
+of the various operating system possibilities, say:
+ use Config;
+ use File::Spec;
+ $thisperl = $^X;
+ $thisperl .= $Config{_exe} unless $thisperl ~= m/$Config{_exe}([;\d]*)$/i;
+
+To convert $Config{perlpath} to a file pathname, say:
+
+ use Config;
+ use File::Spec;
+ $thisperl = File::Spec->canonpath($Config{perlpath});
+ $thisperl .= $Config{_exe} unless $thisperl ~= m/$Config{_exe}([;\d]*)$/i;
+
=head2 Interprocess Communication (IPC)
In general, don't directly access the system in code meant to be
=head2 Character sets and character encoding
-Assume little about character sets. Assume nothing about
-numerical values (C<ord>, C<chr>) of characters. Do not
-assume that the alphabetic characters are encoded contiguously (in
-the numeric sense). Do not assume anything about the ordering of the
-characters. The lowercase letters may come before or after the
-uppercase letters; the lowercase and uppercase may be interlaced so
-that both `a' and `A' come before `b'; the accented and other
-international characters may be interlaced so that E<auml> comes
-before `b'.
+Assume very little about character sets.
+
+Assume nothing about numerical values (C<ord>, C<chr>) of characters.
+Do not use explicit code point ranges (like \xHH-\xHH); use for
+example symbolic character classes like C<[:print:]>.
+
+Do not assume that the alphabetic characters are encoded contiguously
+(in the numeric sense). There may be gaps.
+
+Do not assume anything about the ordering of the characters.
+The lowercase letters may come before or after the uppercase letters;
+the lowercase and uppercase may be interlaced so that both `a' and `A'
+come before `b'; the accented and other international characters may
+be interlaced so that E<auml> comes before `b'.
=head2 Internationalisation
--------------------------------------------
AIX aix aix
BSD/OS bsdos i386-bsdos
+ Darwin darwin darwin
dgux dgux AViiON-dgux
DYNIX/ptx dynixptx i386-dynixptx
FreeBSD freebsd freebsd-i386
The EMX environment for DOS, OS/2, etc. emx@iaehv.nl,
http://www.leo.org/pub/comp/os/os2/leo/gnu/emx+gcc/index.html or
-ftp://hobbes.nmsu.edu/pub/os2/dev/emx. Also L<perlos2>.
+ftp://hobbes.nmsu.edu/pub/os2/dev/emx/ Also L<perlos2>.
=item *
(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
+ C<< $ perl -ne "print if /perl_setup/i" >system>notices >>
+ C<< $ perl -ne "print if /perl_setup/i" /system/notices >>
or even a mixture of both as in:
- $ perl -ne "print if /perl_setup/i" >system/notices
+ C<< $ perl -ne "print if /perl_setup/i" >system/notices >>
Even though VOS allows the slash character to appear in object
names, because the VOS port of Perl interprets it as a pathname
renamed before they can be processed by Perl. Note that VOS limits
file names to 32 or fewer characters.
-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.
+Perl on VOS can be built using two different compilers and two different
+versions of the POSIX runtime. The recommended method for building full
+Perl is with the GNU C compiler and the generally-available version of
+VOS POSIX support. See F<README.vos> (installed as L<perlvos>) for
+restrictions that apply when Perl is built using the VOS Standard C
+compiler or the alpha version of VOS POSIX support.
The value of C<$^O> on VOS is "VOS". To determine the architecture that
you are running on without resorting to loading all of C<%Config> you
=item *
-F<README.vos>
+F<README.vos> (installed as L<perlvos>)
=item *
There is no specific mailing list for Perl on VOS. You can post
comments to the comp.sys.stratus newsgroup, or subscribe to the general
-Stratus mailing list. Send a letter with "Subscribe Info-Stratus" in
+Stratus mailing list. Send a letter with "subscribe Info-Stratus" in
the message body to majordomo@list.stratagy.com.
=item *
-VOS Perl on the web at http://ftp.stratus.com/pub/vos/vos.html
+VOS Perl on the web at http://ftp.stratus.com/pub/vos/posix/posix.html
=back
Access permissions are mapped onto VOS access-control list changes. (VOS)
+The actual permissions set depend on the value of the C<CYGWIN>
+in the SYSTEM environment settings. (Cygwin)
+
=item chown LIST
Not implemented. (S<Mac OS>, Win32, Plan9, S<RISC OS>, VOS)
Not implemented. (Win32, Plan9)
-=item setpwent
-
-Not implemented. (S<Mac OS>, Win32, S<RISC OS>)
-
-=item setgrent
-
-Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>)
-
=item sethostent STAYOPEN
Not implemented. (S<Mac OS>, Win32, Plan9, S<RISC OS>)
=item setgrent
-Not implemented. (MPE/iX, Win32)
+Not implemented. (S<Mac OS>, MPE/iX, VMS, Win32, VMS, S<RISC OS>)
=item setpgrp PID,PGRP
=item setpwent
-Not implemented. (MPE/iX, Win32)
+Not implemented. (S<Mac OS>, MPE/iX, Win32, S<RISC OS>)
=item setsockopt SOCKET,LEVEL,OPTNAME,OPTVAL
'not numeric' warnings.
mtime and atime are the same thing, and ctime is creation time instead of
-inode change time. (S<Mac OS>)
+inode change time. (S<Mac OS>).
+
+ctime not supported on UFS (S<Mac OS X>).
+
+ctime is creation time instead of inode change time (Win32).
device and inode are not meaningful. (Win32)
=item system LIST
+In general, do not assume the UNIX/POSIX semantics that you can shift
+C<$?> right by eight to get the exit value, or that C<$? & 127>
+would give you the number of the signal that terminated the program,
+or that C<$? & 128> would test true if the program was terminated by a
+coredump. Instead, use the POSIX W*() interfaces: for example, use
+WIFEXITED($?) and WEXITVALUE($?) to test for a normal exit and the exit
+value, WIFSIGNALED($?) and WTERMSIG($?) for a signal exit and the
+signal. Core dumping is not a portable concept, so there's no portable
+way to test for that.
+
Only implemented if ToolServer is installed. (S<Mac OS>)
As an optimization, may not call the command shell specified in
=item utime LIST
-Only the modification time is updated. (S<Mac OS>, VMS, S<RISC OS>)
+Only the modification time is updated. (S<BeOS>, S<Mac OS>, VMS, S<RISC OS>)
May not behave as expected. Behavior depends on the C runtime
library's implementation of utime(), and the filesystem being
DG/UX
DOS DJGPP 1)
DYNIX/ptx
- EPOC
+ EPOC R5
FreeBSD
HP-UX
IRIX
Netware
The following platforms have their own source code distributions and
-binaries available via http://www.cpan.org/ports/index.html:
+binaries available via http://www.cpan.org/ports/
Perl release
Larry Moore <ljmoore@freespace.net>,
Paul Moore <Paul.Moore@uk.origin-it.com>,
Chris Nandor <pudge@pobox.com>,
-Matthias Neeracher <neeri@iis.ee.ethz.ch>,
+Matthias Neeracher <neeracher@mac.com>,
Philip Newton <pne@cpan.org>,
Gary Ng <71564.1743@CompuServe.COM>,
Tom Phoenix <rootbeer@teleport.com>,
Dan Sugalski <dan@sidhe.org>,
Nathan Torkington <gnat@frii.com>.
-=head1 VERSION
-
-Version 1.50, last modified 10 Jul 2001
projects / p5sagit/p5-mst-13.2.git / blobdiff