perlport.pod

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    }

Also see:

=over 4

=item *

F<README.vos> (installed as L<perlvos>)

=item *

The VOS mailing list.

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
the message body to [e-mail].

=item *

VOS Perl on the web at http://ftp.stratus.com/pub/vos/posix/posix.html

=back

=head2 EBCDIC Platforms

Recent versions of Perl have been ported to platforms such as OS/400 on
AS/400 minicomputers as well as OS/390, VM/ESA, and BS2000 for S/390
Mainframes.  Such computers use EBCDIC character sets internally (usually
Character Code Set ID 0037 for OS/400 and either 1047 or POSIX-BC for S/390
systems).  On the mainframe perl currently works under the "Unix system
services for OS/390" (formerly known as OpenEdition), VM/ESA OpenEdition, or
the BS200 POSIX-BC system (BS2000 is supported in perl 5.6 and greater).
See L<perlos390> for details.  Note that for OS/400 there is also a port of
Perl 5.8.1/5.9.0 or later to the PASE which is ASCII-based (as opposed to
ILE which is EBCDIC-based), see L<perlos400>. 

As of R2.5 of USS for OS/390 and Version 2.3 of VM/ESA these Unix
sub-systems do not support the C<#!> shebang trick for script invocation.
Hence, on OS/390 and VM/ESA perl scripts can be executed with a header
similar to the following simple script:

    : # use perl
        eval 'exec /usr/local/bin/perl -S $0 ${1+"$@"}'
            if 0;
    #!/usr/local/bin/perl     # just a comment really

    print "Hello from perl!\n";

OS/390 will support the C<#!> shebang trick in release 2.8 and beyond.
Calls to C<system> and backticks can use POSIX shell syntax on all
S/390 systems.

On the AS/400, if PERL5 is in your library list, you may need
to wrap your perl scripts in a CL procedure to invoke them like so:

    BEGIN
      CALL PGM(PERL5/PERL) PARM('/QOpenSys/hello.pl')
    ENDPGM

This will invoke the perl script F<hello.pl> in the root of the
QOpenSys file system.  On the AS/400 calls to C<system> or backticks
must use CL syntax.

On these platforms, bear in mind that the EBCDIC character set may have
an effect on what happens with some perl functions (such as C<chr>,
C<pack>, C<print>, C<printf>, C<ord>, C<sort>, C<sprintf>, C<unpack>), as
well as bit-fiddling with ASCII constants using operators like C<^>, C<&>
and C<|>, not to mention dealing with socket interfaces to ASCII computers
(see L<"Newlines">).

Fortunately, most web servers for the mainframe will correctly
translate the C<\n> in the following statement to its ASCII equivalent
(C<\r> is the same under both Unix and OS/390 & VM/ESA):

    print "Content-type: text/html\r\n\r\n";

The values of C<$^O> on some of these platforms includes:

    uname         $^O        $Config{'archname'}
    --------------------------------------------
    OS/390        os390      os390
    OS400         os400      os400
    POSIX-BC      posix-bc   BS2000-posix-bc
    VM/ESA        vmesa      vmesa

Some simple tricks for determining if you are running on an EBCDIC
platform could include any of the following (perhaps all):

    if ("\t" eq "\05")   { print "EBCDIC may be spoken here!\n"; }

    if (ord('A') == 193) { print "EBCDIC may be spoken here!\n"; }

    if (chr(169) eq 'z') { print "EBCDIC may be spoken here!\n"; }

One thing you may not want to rely on is the EBCDIC encoding
of punctuation characters since these may differ from code page to code
page (and once your module or script is rumoured to work with EBCDIC,
folks will want it to work with all EBCDIC character sets).

Also see:

=over 4

=item *

L<perlos390>, F<README.os390>, F<perlbs2000>, F<README.vmesa>,
L<perlebcdic>.

=item *

The [e-mail] list is for discussion of porting issues as well as
general usage issues for all EBCDIC Perls.  Send a message body of
"subscribe perl-mvs" to [e-mail].

=item *

AS/400 Perl information at
http://as400.rochester.ibm.com/
as well as on CPAN in the F<ports/> directory.

=back

=head2 Acorn RISC OS

Because Acorns use ASCII with newlines (C<\n>) in text files as C<\012> like
Unix, and because Unix filename emulation is turned on by default, 
most simple scripts will probably work "out of the box".  The native
filesystem is modular, and individual filesystems are free to be
case-sensitive or insensitive, and are usually case-preserving.  Some
native filesystems have name length limits, which file and directory
names are silently truncated to fit.  Scripts should be aware that the
standard filesystem currently has a name length limit of B<10>
characters, with up to 77 items in a directory, but other filesystems
may not impose such limitations.

Native filenames are of the form

    Filesystem#Special_Field::DiskName.$.Directory.Directory.File

where

    Special_Field is not usually present, but may contain . and $ .
    Filesystem =~ m|[A-Za-z0-9_]|
    DsicName   =~ m|[A-Za-z0-9_/]|
    $ represents the root directory
    . is the path separator
    @ is the current directory (per filesystem but machine global)
    ^ is the parent directory
    Directory and File =~ m|[^\0- "\.\$\%\&:\@\\^\|\177]+|

The default filename translation is roughly C<tr|/.|./|;>

Note that C<"ADFS::HardDisk.$.File" ne 'ADFS::HardDisk.$.File'> and that
the second stage of C<$> interpolation in regular expressions will fall
foul of the C<$.> if scripts are not careful.

Logical paths specified by system variables containing comma-separated
search lists are also allowed; hence C<System:Modules> is a valid
filename, and the filesystem will prefix C<Modules> with each section of
C<System$Path> until a name is made that points to an object on disk.
Writing to a new file C<System:Modules> would be allowed only if
C<System$Path> contains a single item list.  The filesystem will also
expand system variables in filenames if enclosed in angle brackets, so
C<< <System$Dir>.Modules >> would look for the file
S<C<$ENV{'System$Dir'} . 'Modules'>>.  The obvious implication of this is
that B<fully qualified filenames can start with C<< <> >>> and should
be protected when C<open> is used for input.

Because C<.> was in use as a directory separator and filenames could not
be assumed to be unique after 10 characters, Acorn implemented the C
compiler to strip the trailing C<.c> C<.h> C<.s> and C<.o> suffix from
filenames specified in source code and store the respective files in
subdirectories named after the suffix.  Hence files are translated:

    foo.h           h.foo
    C:foo.h         C:h.foo        (logical path variable)
    sys/os.h        sys.h.os       (C compiler groks Unix-speak)
    10charname.c    c.10charname
    10charname.o    o.10charname
    11charname_.c   c.11charname   (assuming filesystem truncates at 10)

The Unix emulation library's translation of filenames to native assumes
that this sort of translation is required, and it allows a user-defined list
of known suffixes that it will transpose in this fashion.  This may
seem transparent, but consider that with these rules C<foo/bar/baz.h>
and C<foo/bar/h/baz> both map to C<foo.bar.h.baz>, and that C<readdir> and
C<glob> cannot and do not attempt to emulate the reverse mapping.  Other
C<.>'s in filenames are translated to C</>.

As implied above, the environment accessed through C<%ENV> is global, and
the convention is that program specific environment variables are of the
form C<Program$Name>.  Each filesystem maintains a current directory,
and the current filesystem's current directory is the B<global> current
directory.  Consequently, sociable programs don't change the current
directory but rely on full pathnames, and programs (and Makefiles) cannot
assume that they can spawn a child process which can change the current
directory without affecting its parent (and everyone else for that
matter).

Because native operating system filehandles are global and are currently 
allocated down from 255, with 0 being a reserved value, the Unix emulation
library emulates Unix filehandles.  Consequently, you can't rely on
passing C<STDIN>, C<STDOUT>, or C<STDERR> to your children.

The desire of users to express filenames of the form
C<< <Foo$Dir>.Bar >> on the command line unquoted causes problems,
too: C<``> command output capture has to perform a guessing game.  It
assumes that a string C<< <[^<>]+\$[^<>]> >> is a
reference to an environment variable, whereas anything else involving
C<< < >> or C<< > >> is redirection, and generally manages to be 99%
right.  Of course, the problem remains that scripts cannot rely on any
Unix tools being available, or that any tools found have Unix-like command
line arguments.

Extensions and XS are, in theory, buildable by anyone using free
tools.  In practice, many don't, as users of the Acorn platform are
used to binary distributions.  MakeMaker does run, but no available
make currently copes with MakeMaker's makefiles; even if and when
this should be fixed, the lack of a Unix-like shell will cause
problems with makefile rules, especially lines of the form C<cd
sdbm && make all>, and anything using quoting.

"S<RISC OS>" is the proper name for the operating system, but the value
in C<$^O> is "riscos" (because we don't like shouting).

=head2 Other perls

Perl has been ported to many platforms that do not fit into any of
the categories listed above.  Some, such as AmigaOS, Atari MiNT,
BeOS, HP MPE/iX, QNX, Plan 9, and VOS, have been well-integrated
into the standard Perl source code kit.  You may need to see the
F<ports/> directory on CPAN for information, and possibly binaries,
for the likes of: aos, Atari ST, lynxos, riscos, Novell Netware,
Tandem Guardian, I<etc.>  (Yes, we know that some of these OSes may
fall under the Unix category, but we are not a standards body.)

Some approximate operating system names and their C<$^O> values
in the "OTHER" category include:

    OS            $^O        $Config{'archname'}
    ------------------------------------------
    Amiga DOS     amigaos    m68k-amigos
    BeOS          beos
    MPE/iX        mpeix      PA-RISC1.1

See also:

=over 4

=item *

Amiga, F<README.amiga> (installed as L<perlamiga>).

=item *

Atari, F<README.mint> and Guido Flohr's web page
http://stud.uni-sb.de/~gufl0000/

=item *

Be OS, F<README.beos>

=item *

HP 300 MPE/iX, F<README.mpeix> and Mark Bixby's web page
http://www.bixby.org/mark/perlix.html

=item *

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  *

S<Plan 9>, F<README.plan9>

=back

=head1 FUNCTION IMPLEMENTATIONS

Listed below are functions that are either completely unimplemented
or else have been implemented differently on various platforms.
Following each description will be, in parentheses, a list of
platforms that the description applies to.

The list may well be incomplete, or even wrong in some places.  When
in doubt, consult the platform-specific README files in the Perl
source distribution, and any other documentation resources accompanying
a given port.

Be aware, moreover, that even among Unix-ish systems there are variations.

For many functions, you can also query C<%Config>, exported by
default from the Config module.  For example, to check whether the
platform has the C<lstat> call, check C<$Config{d_lstat}>.  See
L<Config> for a full description of available variables.

=head2 Alphabetical Listing of Perl Functions

=over 8

=item -X

C<-r>, C<-w>, and C<-x> have a limited meaning only; directories
and applications are executable, and there are no uid/gid
considerations.  C<-o> is not supported.  (S<Mac OS>)

C<-r>, C<-w>, C<-x>, and C<-o> tell whether the file is accessible,
which may not reflect UIC-based file protections.  (VMS)

C<-s> returns the size of the data fork, not the total size of