features.
This document is meant to help you to find out what constitutes portable
-perl code, so that once you have made your decision to write portably,
+Perl code, so that once you have made your decision to write portably,
you know where the lines are drawn, and you can stay within them.
-There is a tradeoff between taking full advantage of B<a> particular type
-of computer, and taking advantage of a full B<range> of them. Naturally,
-as you make your range bigger (and thus more diverse), the common denominators
-drop, and you are left with fewer areas of common ground in which
-you can operate to accomplish a particular task. Thus, when you begin
-attacking a problem, it is important to consider which part of the tradeoff
-curve you want to operate under. Specifically, whether it is important to
-you that the task that you are coding needs the full generality of being
-portable, or if it is sufficient to just get the job done. This is the
-hardest choice to be made. The rest is easy, because Perl provides lots
-of choices, whichever way you want to approach your problem.
-
-Looking at it another way, writing portable code is usually about willfully
-limiting your available choices. Naturally, it takes discipline to do that.
+There is a tradeoff between taking full advantage of one particular type
+of computer, and taking advantage of a full range of them. Naturally,
+as you make your range bigger (and thus more diverse), the common
+denominators drop, and you are left with fewer areas of common ground in
+which you can operate to accomplish a particular task. Thus, when you
+begin attacking a problem, it is important to consider which part of the
+tradeoff curve you want to operate under. Specifically, whether it is
+important to you that the task that you are coding needs the full
+generality of being portable, or if it is sufficient to just get the job
+done. This is the hardest choice to be made. The rest is easy, because
+Perl provides lots of choices, whichever way you want to approach your
+problem.
+
+Looking at it another way, writing portable code is usually about
+willfully limiting your available choices. Naturally, it takes discipline
+to do that.
Be aware of two important points:
+
=over 4
=item Not all Perl programs have to be portable
Windows registry. If it makes no sense to aim for portability for one
reason or another in a given program, then don't bother.
-=item The vast majority of Perl B<is> portable
+=item The vast majority of Perl I<is> portable
Don't be fooled into thinking that it is hard to create portable Perl
code. It isn't. Perl tries its level-best to bridge the gaps between
what's available on different platforms, and all the means available to
use those features. Thus almost all Perl code runs on any machine
-without modification. But there I<are> some significant issues in
+without modification. But there are some significant issues in
writing portable code, and this document is entirely about those issues.
=back
+
Here's the general rule: When you approach a task that is commonly done
using a whole range of platforms, think in terms of writing portable
code. That way, you don't sacrifice much by way of the implementation
often the case with systems programming (whether for Unix, Windows,
S<Mac OS>, VMS, etc.), consider writing platform-specific code.
-When the code will run on only two or three operating systems, then you may
-only need to consider the differences of those particular systems. The
-important thing is to decide where the code will run, and to be deliberate
-in your decision.
+When the code will run on only two or three operating systems, then you
+may only need to consider the differences of those particular systems.
+The important thing is to decide where the code will run, and to be
+deliberate in your decision.
+
+The material below is separated into three main sections: main issues of
+portability (L<"ISSUES">, platform-specific issues (L<"PLATFORMS">, and
+builtin perl functions that behave differently on various ports
+(L<"FUNCTION IMPLEMENTATIONS">.
This information should not be considered complete; it includes possibly
transient information about idiosyncrasies of some of the ports, almost
=head2 Newlines
-In most operating systems, lines in files are separated with newlines.
+In most operating systems, lines in files are terminated by newlines.
Just what is used as a newline may vary from OS to OS. Unix
traditionally uses C<\012>, one kind of Windows I/O uses C<\015\012>,
and S<Mac OS> uses C<\015>.
is logical may depend on the platform in use. In MacPerl, C<\n>
always means C<\015>. In DOSish perls, C<\n> usually means C<\012>, but
when accessing a file in "text" mode, STDIO translates it to (or from)
-C<\015\012>.
+C<\015\012>. C<\015\012> is commonly referred to as CRLF.
Due to the "text" mode translation, DOSish perls have limitations
of using C<seek> and C<tell> when a file is being accessed in "text"
with arbitrary values quite safely.
A common misconception in socket programming is that C<\n> eq C<\012>
-everywhere. When using protocols, such as common Internet protocols,
+everywhere. When using protocols such as common Internet protocols,
C<\012> and C<\015> are called for specifically, and the values of
the logical C<\n> and C<\r> (carriage return) are not reliable.
print SOCKET "Hi there, client!\r\n"; # WRONG
print SOCKET "Hi there, client!\015\012"; # RIGHT
-[NOTE: this does not necessarily apply to communications that are
-filtered by another program or module before sending to the socket; the
-the most popular EBCDIC webserver, for instance, accepts C<\r\n>,
-which translates those characters, along with all other
-characters in text streams, from EBCDIC to ASCII.]
-
-However, C<\015\012> (or C<\cM\cJ>, or C<\x0D\x0A>) can be tedious and
-unsightly, as well as confusing to those maintaining the code. As such,
-the C<Socket> module supplies the Right Thing for those who want it.
+However, using C<\015\012> (or C<\cM\cJ>, or C<\x0D\x0A>) can be tedious
+and unsightly, as well as confusing to those maintaining the code. As
+such, the Socket module supplies the Right Thing for those who want it.
use Socket qw(:DEFAULT :crlf);
print SOCKET "Hi there, client!$CRLF" # RIGHT
-When reading I<from> a socket, remember that the default input record
-separator (C<$/>) is C<\n>, but code like this should recognize C<$/> as
+When reading from a socket, remember that the default input record
+separator C<$/> is C<\n>, but code like this should recognize C<$/> as
C<\012> or C<\015\012>:
while (<SOCKET>) {
# ...
}
-Better:
+Since both CRLF and LF end in LF, the input record separator can
+be set to LF, and the CR can be stripped later, if present. Better:
use Socket qw(:DEFAULT :crlf);
local($/) = LF; # not needed if $/ is already \012
platforms, because now any C<\015>'s (C<\cM>'s) are stripped out
(and there was much rejoicing).
+Similarly, functions that return text data--such as a function that
+fetches a web page--should, in some cases, translate newlines before
+returning the data, if they've not yet been trsnalted to the local
+newline. Often one line of code will suffice:
+
+ $data =~ s/\015?\012/\n/g;
+ return $data;
+
+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
+
+ | Unix | DOS | Mac |
+ ---------------------------
+ \n | LF | LF | CR |
+ \r | CR | CR | LF |
+ \n * | LF | CRLF | CR |
+ \r * | CR | CR | LF |
+ ---------------------------
+ * text-mode STDIO
+
+These are just the most common definitions of C<\n> and C<\r> in Perl.
+There may well be others.
+
-=head2 File Paths
+=head2 Numbers endianness and Width
+
+Different CPUs store integers and floating point numbers in different
+orders (called I<endianness>) and widths (32-bit and 64-bit being the
+most common). This affects your programs if they attempt to transfer
+numbers in binary format from one CPU architecture to another over some
+channel, usually either "live" via network connection, or by storing the
+numbers to secondary storage such as a disk file.
+
+Conflicting storage orders make utter mess out of the numbers: if a
+little-endian host (Intel, Alpha) stores 0x12345678 (305419896 in
+decimal), a big-endian host (Motorola, MIPS, Sparc, PA) reads it as
+0x78563412 (2018915346 in decimal). To avoid this problem in network
+(socket) connections use the C<pack> and C<unpack> formats C<n>
+and C<N>, the "network" orders. They are guaranteed to be portable.
+
+Different widths can cause truncation even between platforms of equal
+endianness: the platform of shorter width loses the upper parts of the
+number. There is no good solution for this problem except to avoid
+transferring or storing raw binary numbers.
+
+One can circumnavigate both these problems in two ways: either
+transfer and store numbers always in text format, instead of raw
+binary, or consider using modules like Data::Dumper (included in
+the standard distribution as of Perl 5.005) and Storable.
+
+
+=head2 Files and Filesystems
Most platforms these days structure files in a hierarchical fashion.
So, it is reasonably safe to assume that any platform supports the
-notion of a "path" to uniquely identify a file on the system. Just
-how that path is actually written, differs.
+notion of a "path" to uniquely identify a file on the system. How
+that path is actually written differs.
While they are similar, file path specifications differ between Unix,
-Windows, S<Mac OS>, OS/2, VMS, S<RISC OS> and probably others. Unix,
-for example, is one of the few OSes that has the idea of a root directory.
-S<Mac OS> uses C<:> as a path separator instead of C</>. VMS, Windows, and
-OS/2 can work similarly to Unix with C</> as path separator, or in their own
-idiosyncratic ways. C<RISC OS> perl can emulate Unix filenames with C</>
-as path separator, or go native and use C<.> for path separator and C<:>
-to signal filing systems and disc names.
-
-As with the newline problem above, there are modules that can help. The
-C<File::Spec> modules provide methods to do the Right Thing on whatever
+Windows, S<Mac OS>, OS/2, VMS, VOS, S<RISC OS> and probably others.
+Unix, for example, is one of the few OSes that has the idea of a single
+root directory.
+
+DOS, OS/2, VMS, VOS, and Windows can work similarly to Unix with C</>
+as path separator, or in their own idiosyncratic ways (such as having
+several root directories and various "unrooted" device files such NIL:
+and LPT:).
+
+S<Mac OS> uses C<:> as a path separator instead of C</>.
+
+The filesystem may support neither hard links (C<link>) nor
+symbolic links (C<symlink>, C<readlink>, C<lstat>).
+
+The filesystem may support neither access timestamp nor change
+timestamp (meaning that about the only portable timestamp is the
+modification timestamp), or one second granularity of any timestamps
+(e.g. the FAT filesystem limits the time granularity to two seconds).
+
+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.
+
+S<RISC OS> perl can emulate Unix filenames with C</> as path
+separator, or go native and use C<.> for path separator and C<:> to
+signal filesystems and disk names.
+
+If all this is intimidating, have no (well, maybe only a little) fear.
+There are modules that can help. The File::Spec modules provide
+methods to do the Right Thing on whatever
platform happens to be running the program.
- use File::Spec;
- chdir(File::Spec->updir()); # go up one directory
- $file = File::Spec->catfile(
- File::Spec->curdir(), 'temp', 'file.txt'
- );
+ use File::Spec::Functions;
+ chdir(updir()); # go up one directory
+ $file = catfile(curdir(), 'temp', 'file.txt');
# on Unix and Win32, './temp/file.txt'
# on Mac OS, ':temp:file.txt'
This is especially noticeable in scripts like Makefiles and test suites,
which often assume C</> as a path separator for subdirectories.
-Also of use is C<File::Basename>, from the standard distribution, which
+Also of use is File::Basename, from the standard distribution, which
splits a pathname into pieces (base filename, full path to directory,
and file suffix).
-Remember not to count on the existence of system-specific files, like
-F</etc/resolv.conf>. If code does need to rely on such a file, include a
-description of the file and its format in the code's documentation, and
-make it easy for the user to override the default location of the file.
+Even when on a single platform (if you can call UNIX a single platform),
+remember not to count on the existence or the contents of
+system-specific files or directories, like F</etc/passwd>,
+F</etc/sendmail.conf>, F</etc/resolv.conf>, or even F</tmp/>. For
+example, F</etc/passwd> may exist but it may not contain the encrypted
+passwords because the system is using some form of enhanced security,
+or it may not contain all the accounts because the system is using NIS.
+If code does need to rely on such a file, include a description of the
+file and its format in the code's documentation, and make it easy for
+the user to override the default location of the file.
+
+Don't assume a text file will end with a newline.
+
+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.
-Don't assume that a you can open a full pathname for input with
-C<open (FILE, $name)>, as some platforms can use characters such as C<E<lt>>
-which will perl C<open> will interpret and eat.
+Likewise, if using the AutoSplit module, try to keep the split functions to
+8.3 naming and case-insensitive conventions; or, at the very least,
+make it so the resulting files have a unique (case-insensitively)
+first 8 characters.
+
+There certainly can be whitespace in filenames on most systems, but
+some may not allow it. Many systems (DOS, VMS) cannot have more than
+one C<.> in their filenames.
+
+Don't assume C<E<gt>> won't be the first character of a filename.
+Always use C<E<lt>> explicitly to open a file for reading.
+
+ open(FILE, "< $existing_file") or die $!;
+
+If filenames might use strange characters, it is safest to open it
+with C<sysopen> instead of C<open>. C<open> is magic and can
+translate characters like C<E<gt>>, C<E<lt>>, and C<|>, which may
+be the wrong thing to do.
=head2 System Interaction
These are usually platforms that rely on a Graphical User Interface (GUI)
for user interaction. So a program requiring command lines might not work
everywhere. But this is probably for the user of the program to deal
-with.
+with, so don't stay up late worrying about it.
Some platforms can't delete or rename files that are being held open by
the system. Remember to C<close> files when you are done with them.
-Don't C<unlink> or C<rename> an open file. Don't C<tie> to or C<open> a
-file that is already tied to or opened; C<untie> or C<close> first.
+Don't C<unlink> or C<rename> an open file. Don't C<tie> or C<open> a
+file that is already tied or opened; C<untie> or C<close> first.
+
+Don't open the same file more than once at a time for writing, as some
+operating systems put mandatory locks on such files.
Don't count on a specific environment variable existing in C<%ENV>.
-Don't even count on C<%ENV> entries being case-sensitive, or even
+Don't count on C<%ENV> entries being case-sensitive, or even
case-preserving.
-Don't count on signals in portable programs.
+Don't count on signals for anything.
Don't count on filename globbing. Use C<opendir>, C<readdir>, and
C<closedir> instead.
Don't count on per-program environment variables, or per-program current
-directores.
+directories.
+
+Don't count on specific values of C<$!>.
=head2 Interprocess Communication (IPC)
In general, don't directly access the system in code that is meant to be
-portable. That means, no: C<system>, C<exec>, C<fork>, C<pipe>, C<``>,
-C<qx//>, C<open> with a C<|>, or any of the other things that makes being
+portable. That means, no C<system>, C<exec>, C<fork>, C<pipe>, C<``>,
+C<qx//>, C<open> with a C<|>, nor any of the other things that makes being
a Unix perl hacker worth being.
Commands that launch external processes are generally supported on
platform-dependent way. Thus you should seldom depend on them to produce
consistent results.
+The UNIX System V IPC (msg*(), sem*(), shm*()) is not available
+even in all UNIX platforms.
+
One especially common bit of Perl code is opening a pipe to sendmail:
- open(MAIL, '|/usr/lib/sendmail -t') or die $!;
+ open(MAIL, '| /usr/lib/sendmail -t') or die $!;
This is fine for systems programming when sendmail is known to be
available. But it is not fine for many non-Unix systems, and even
some Unix systems that may not have sendmail installed. If a portable
-solution is needed, see the C<Mail::Send> and C<Mail::Mailer> modules
-in the C<MailTools> distribution. C<Mail::Mailer> provides several
-mailing methods, including mail, sendmail, and direct SMTP
-(via C<Net::SMTP>) if a mail transfer agent is not available.
+solution is needed, see the various distributions on CPAN that deal with
+it. Mail::Mailer and Mail::Send in the MailTools distribution
+are commonly used, and provide several mailing methods, including mail,
+sendmail, and direct SMTP (via Net::SMTP) if a mail transfer agent is
+not available. Mail::Sendmail is a standalone module that provides
+simple, platform-independent mailing.
The rule of thumb for portable code is: Do it all in portable Perl, or
-use a module that may internally implement it with platform-specific code,
-but expose a common interface. By portable Perl, we mean code that
-avoids the constructs described in this document as being non-portable.
+use a module (that may internally implement it with platform-specific
+code, but expose a common interface).
=head2 External Subroutines (XS)
normally reasonable to make sure the XS code is portable, too.
There is a different kind of portability issue with writing XS
-code: availability of a C compiler on the end-user's system. C brings with
-it its own portability issues, and writing XS code will expose you to
+code: availability of a C compiler on the end-user's system. C brings
+with it its own portability issues, and writing XS code will expose you to
some of those. Writing purely in perl is a comparatively easier way to
achieve portability.
=head2 Standard Modules
In general, the standard modules work across platforms. Notable
-exceptions are C<CPAN.pm> (which currently makes connections to external
+exceptions are the CPAN module (which currently makes connections to external
programs that may not be available), platform-specific modules (like
-C<ExtUtils::MM_VMS>), and DBM modules.
+ExtUtils::MM_VMS), and DBM modules.
There is no one DBM module that is available on all platforms.
-C<SDBM_File> and the others are generally available on all Unix and DOSish
-ports, but not in MacPerl, where C<NBDM_File> and C<DB_File> are available.
+SDBM_File and the others are generally available on all Unix and DOSish
+ports, but not in MacPerl, where only NBDM_File and DB_File are
+available.
The good news is that at least some DBM module should be available, and
-C<AnyDBM_File> will use whichever module it can find. Of course, then
+AnyDBM_File will use whichever module it can find. Of course, then
the code needs to be fairly strict, dropping to the lowest common
-denominator (e.g., not exceeding 1K for each record).
+denominator (e.g., not exceeding 1K for each record), so that it will
+work with any DBM module. See L<AnyDBM_File> for more details.
=head2 Time and Date
-The system's notion of time of day and calendar date is controlled in widely
-different ways. Don't assume the timezone is stored in C<$ENV{TZ}>, and even
-if it is, don't assume that you can control the timezone through that
-variable.
+The system's notion of time of day and calendar date is controlled in
+widely different ways. Don't assume the timezone is stored in C<$ENV{TZ}>,
+and even if it is, don't assume that you can control the timezone through
+that variable.
+
+Don't assume that the epoch starts at 00:00:00, January 1, 1970,
+because that is OS- and implementation-specific. It is better to store a date
+in an unambiguous representation. The ISO-8601 standard defines
+"YYYY-MM-DD" as the date format. A text representation (like "1987-12-18")
+can be easily converted into an OS-specific value using a module like
+Date::Parse. An array of values, such as those returned by
+C<localtime>, can be converted to an OS-specific representation using
+Time::Local.
+
+
+=head2 Character sets and character encoding
-Don't assume that the epoch starts at January 1, 1970, because that is
-OS-specific. Better to store a date in an unambiguous representation.
-A text representation (like C<1 Jan 1970>) can be easily converted into an
-OS-specific value using a module like C<Date::Parse>. An array of values,
-such as those returned by C<localtime>, can be converted to an OS-specific
-representation using C<Time::Local>.
+Assume very little about character sets. Do not assume anything about
+the numerical values (C<ord>, C<chr>) of characters. Do not
+assume that the alphabetic characters are encoded contiguously (in
+numerical 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 the 'b', the accented and other
+international characters may be interlaced so that E<auml> comes
+before the 'b'.
+
+
+=head2 Internationalisation
+
+If you may assume POSIX (a rather large assumption, that in practice
+means UNIX), you may read more about the POSIX locale system (see
+L<perllocale>. The locale system at least attempts to make things a
+little bit more portable, or at least more convenient and
+native-friendly for non-English users. The system affects character
+sets and encoding, and date and time formatting, among other things.
=head2 System Resources
-If your code is destined for systems with severely constrained (or missing!)
-virtual memory systems then you want to be especially mindful of avoiding
-wasteful constructs such as:
+If your code is destined for systems with severely constrained (or
+missing!) virtual memory systems then you want to be I<especially> mindful
+of avoiding wasteful constructs such as:
# NOTE: this is no longer "bad" in perl5.005
for (0..10000000) {} # bad
@lines = <VERY_LARGE_FILE>; # bad
while (<FILE>) {$file .= $_} # sometimes bad
- $file = join '', <FILE>; # better
+ $file = join('', <FILE>); # better
The last two may appear unintuitive to most people. The first of those
two constructs repeatedly grows a string, while the second allocates a
large chunk of memory in one go. On some systems, the latter is more
efficient that the former.
+
=head2 Security
-Most Unix platforms provide basic levels of security that is usually felt
-at the file-system level. Other platforms usually don't (unfortunately).
-Thus the notion of User-ID, or "home" directory, or even the state of
-being logged-in may be unrecognizable on may platforms. If you write
-programs that are security conscious, it is usually best to know what
-type of system you will be operating under, and write code explicitly
+Most multi-user platforms provide basic levels of security that is usually
+felt at the file-system level. Other platforms usually don't
+(unfortunately). Thus the notion of user id, or "home" directory, or even
+the state of being logged-in, may be unrecognizable on many platforms. If
+you write programs that are security-conscious, it is usually best to know
+what type of system you will be operating under, and write code explicitly
for that platform (or class of platforms).
+
=head2 Style
For those times when it is necessary to have platform-specific code,
consider keeping the platform-specific code in one place, making porting
-to other platforms easier. Use the C<Config> module and the special
-variable C<$^O> to differentiate platforms, as described in L<"PLATFORMS">.
+to other platforms easier. Use the Config module and the special
+variable C<$^O> to differentiate platforms, as described in
+L<"PLATFORMS">.
+Be careful not to depend on a specific output style for errors,
+such as when checking C<$@> after an C<eval>. Some platforms
+expect a certain output format, and perl on those platforms may
+have been adjusted accordingly. Most specifically, don't anchor
+a regex when testing an error value.
-=head1 CPAN TESTERS
+ $@ =~ /^I got an error!/ # may fail
+ $@ =~ /I got an error!/ # probably better
-Module uploaded to CPAN are tested by a variety of volunteers on
-different platforms. These CPAN testers are notified by e-mail of each
+
+=head1 CPAN Testers
+
+Modules uploaded to CPAN are tested by a variety of volunteers on
+different platforms. These CPAN testers are notified by mail of each
new upload, and reply to the list with PASS, FAIL, NA (not applicable to
-this platform), or ???? (unknown), along with any relevant notations.
+this platform), or UNKNOWN (unknown), along with any relevant notations.
The purpose of the testing is twofold: one, to help developers fix any
-problems in their code; two, to provide users with information about
-whether or not a given module works on a given platform.
+problems in their code that crop up because of lack of testing on other
+platforms; two, to provide users with information about whether or not
+a given module works on a given platform.
=over 4
=item Mailing list: cpan-testers@perl.org
-=item Testing results: C<http://www.connect.net/gbarr/cpan-test/>
+=item Testing results: C<http://www.perl.org/cpan-testers/>
=back
detailed information about the system, looking into C<%Config> is
certainly recommended.
+C<%Config> cannot always be trusted, however,
+because it is built at compile time, and if perl was built in once
+place and transferred elsewhere, some values may be off, or the
+values may have been edited after the fact.
+
+
=head2 Unix
Perl works on a bewildering variety of Unix and Unix-like platforms (see
e.g. most of the files in the F<hints/> directory in the source code kit).
On most of these systems, the value of C<$^O> (hence C<$Config{'osname'}>,
too) is determined by lowercasing and stripping punctuation from the first
-field of the string returned by typing
-
- % uname -a
+field of the string returned by typing C<uname -a> (or a similar command)
+at the shell prompt. Here, for example, are a few of the more popular
+Unix flavors:
-(or a similar command) at the shell prompt. Here, for example, are a few
-of the more popular Unix flavors:
-
- uname $^O
- --------------------
- AIX aix
- FreeBSD freebsd
- Linux linux
- HP-UX hpux
- OSF1 dec_osf
- SunOS solaris
- SunOS4 sunos
+ uname $^O $Config{'archname'}
+ --------------------------------------------
+ AIX aix aix
+ BSD/OS bsdos i386-bsdos
+ dgux dgux AViiON-dgux
+ DYNIX/ptx dynixptx i386-dynixptx
+ FreeBSD freebsd freebsd-i386
+ Linux linux i386-linux
+ Linux linux i586-linux
+ Linux linux ppc-linux
+ HP-UX hpux PA-RISC1.1
+ IRIX irix irix
+ openbsd openbsd i386-openbsd
+ OSF1 dec_osf alpha-dec_osf
+ reliantunix-n svr4 RM400-svr4
+ SCO_SV sco_sv i386-sco_sv
+ SINIX-N svr4 RM400-svr4
+ sn4609 unicos CRAY_C90-unicos
+ sn6521 unicosmk t3e-unicosmk
+ sn9617 unicos CRAY_J90-unicos
+ sn9716 unicos CRAY_J90-unicos
+ SunOS solaris sun4-solaris
+ SunOS solaris i86pc-solaris
+ SunOS4 sunos sun4-sunos
+
+Note that because the C<$Config{'archname'}> may depend on the hardware
+architecture it may vary quite a lot, much more than the C<$^O>.
=head2 DOS and Derivatives
probably better, as it is more consistent with popular usage, and avoids
the problem of remembering what to backwhack and what not to.
-The DOS FAT file system can only accommodate "8.3" style filenames. Under
+The DOS FAT filesystem can only accommodate "8.3" style filenames. Under
the "case insensitive, but case preserving" HPFS (OS/2) and NTFS (NT)
-file systems you may have to be careful about case returned with functions
+filesystems you may have to be careful about case returned with functions
like C<readdir> or used with functions like C<open> or C<opendir>.
DOS also treats several filenames as special, such as AUX, PRN, NUL, CON,
and its derivatives.
Users of these operating systems may also wish to make use of
-scripts such as I<pl2bat.bat> or I<pl2cmd> as appropriate to
+scripts such as F<pl2bat.bat> or F<pl2cmd> as appropriate to
put wrappers around your scripts.
Newline (C<\n>) is translated as C<\015\012> by STDIO when reading from
-and writing to files. C<binmode(FILEHANDLE)> will keep C<\n> translated
-as C<\012> for that filehandle. Since it is a noop on other systems,
-C<binmode> should be used for cross-platform code that deals with binary
-data.
+and writing to files (see L<"Newlines">). C<binmode(FILEHANDLE)>
+will keep C<\n> translated as C<\012> for that filehandle. Since it is a
+no-op on other systems, C<binmode> should be used for cross-platform code
+that deals with binary data.
The C<$^O> variable and the C<$Config{'archname'}> values for various
DOSish perls are as follows:
PC-DOS dos
OS/2 os2
Windows 95 MSWin32 MSWin32-x86
+ Windows 98 MSWin32 MSWin32-x86
Windows NT MSWin32 MSWin32-x86
- Windows NT MSWin32 MSWin32-alpha
+ Windows NT MSWin32 MSWin32-ALPHA
Windows NT MSWin32 MSWin32-ppc
Also see:
=item The djgpp environment for DOS, C<http://www.delorie.com/djgpp/>
=item The EMX environment for DOS, OS/2, etc. C<emx@iaehv.nl>,
-C<http://www.juge.com/bbs/Hobb.19.html>
+C<http://www.leo.org/pub/comp/os/os2/leo/gnu/emx+gcc/index.html> or
+C<ftp://hobbes.nmsu.edu/pub/os2/dev/emx>
=item Build instructions for Win32, L<perlwin32>.
=back
-=head2 MacPerl
+=head2 S<Mac OS>
Any module requiring XS compilation is right out for most people, because
MacPerl is built using non-free (and non-cheap!) compilers. Some XS
modules that can work with MacPerl are built and distributed in binary
-form on CPAN. See I<MacPerl: Power and Ease> for more details.
+form on CPAN.
Directories are specified as:
file for relative pathnames
Files in a directory are stored in alphabetical order. Filenames are
-limited to 31 characters, and may include any character except C<:>,
-which is reserved as a path separator.
+limited to 31 characters, and may include any character except for
+null and C<:>, which is reserved as path separator.
-Instead of C<flock>, see C<FSpSetFLock> and C<FSpRstFLock> in
-C<Mac::Files>.
+Instead of C<flock>, see C<FSpSetFLock> and C<FSpRstFLock> in the
+Mac::Files module, or C<chmod(0444, ...)> and C<chmod(0666, ...)>.
In the MacPerl application, you can't run a program from the command line;
programs that expect C<@ARGV> to be populated can be edited with something
perl myscript.plx some arguments
ToolServer is another app from Apple that provides access to MPW tools
-from MPW and the MacPerl app, which allows MacPerl program to use
+from MPW and the MacPerl app, which allows MacPerl programs to use
C<system>, backticks, and piped C<open>.
"S<Mac OS>" is the proper name for the operating system, but the value
$is_ppc = $MacPerl::Architecture eq 'MacPPC';
$is_68k = $MacPerl::Architecture eq 'Mac68K';
+S<Mac OS X> and S<Mac OS X Server>, based on NeXT's OpenStep OS, will
+(in theory) be able to run MacPerl natively, under the "Classic"
+environment. The new "Cocoa" environment (formerly called the "Yellow Box")
+may run a slightly modified version of MacPerl, using the Carbon interfaces.
+
+S<Mac OS X Server> and its Open Source version, Darwin, both run Unix
+perl natively (with a small number of patches). Full support for these
+is slated for perl5.006.
+
Also see:
=over 4
-=item The MacPerl Pages, C<http://www.ptf.com/macperl/>.
+=item The MacPerl Pages, C<http://www.macperl.com/>.
+
+=item The MacPerl mailing lists, C<http://www.macperl.org/>.
-=item The MacPerl mailing list, C<mac-perl-request@iis.ee.ethz.ch>.
+=item MacPerl Module Porters, C<http://pudge.net/mmp/>.
=back
=head2 VMS
Perl on VMS is discussed in F<vms/perlvms.pod> in the perl distribution.
-Note that perl on VMS can accept either VMS or Unix style file
+Note that perl on VMS can accept either VMS- or Unix-style file
specifications as in either of the following:
$ perl -ne "print if /perl_setup/i" SYS$LOGIN:LOGIN.COM
C<readdir> returns lowercased filenames, but specifying a file for
opening remains case insensitive. Files without extensions have a
trailing period on them, so doing a C<readdir> with a file named F<A.;5>
-will return F<a.> (though that file could be opened with C<open(FH, 'A')>.
+will return F<a.> (though that file could be opened with
+C<open(FH, 'A')>).
-RMS has an eight level limit on directory depths from any rooted logical
-(allowing 16 levels overall). Hence C<PERL_ROOT:[LIB.2.3.4.5.6.7.8]>
-is a valid directory specification but C<PERL_ROOT:[LIB.2.3.4.5.6.7.8.9]>
-is not. F<Makefile.PL> authors might have to take this into account, but
-at least they can refer to the former as C</PERL_ROOT/lib/2/3/4/5/6/7/8/>.
+RMS had an eight level limit on directory depths from any rooted logical
+(allowing 16 levels overall) prior to VMS 7.2. Hence
+C<PERL_ROOT:[LIB.2.3.4.5.6.7.8]> is a valid directory specification but
+C<PERL_ROOT:[LIB.2.3.4.5.6.7.8.9]> is not. F<Makefile.PL> authors might
+have to take this into account, but at least they can refer to the former
+as C</PERL_ROOT/lib/2/3/4/5/6/7/8/>.
-The C<VMS::Filespec> module, which gets installed as part
-of the build process on VMS, is a pure Perl module that can easily be
-installed on non-VMS platforms and can be helpful for conversions to
-and from RMS native formats.
+The VMS::Filespec module, which gets installed as part of the build
+process on VMS, is a pure Perl module that can easily be installed on
+non-VMS platforms and can be helpful for conversions to and from RMS
+native formats.
What C<\n> represents depends on the type of file that is open. It could
be C<\015>, C<\012>, C<\015\012>, or nothing. Reading from a file
if (grep(/VMS_AXP/, @INC)) {
print "I'm on Alpha!\n";
+
} elsif (grep(/VMS_VAX/, @INC)) {
print "I'm on VAX!\n";
+
} else {
print "I'm not so sure about where $^O is...\n";
}
+On VMS perl determines the UTC offset from the C<SYS$TIMEZONE_DIFFERENTIAL>
+logical name. Though the VMS epoch began at 17-NOV-1858 00:00:00.00,
+calls to C<localtime> are adjusted to count offsets from
+01-JAN-1970 00:00:00.00 just like Unix.
+
Also see:
=over 4
=item L<perlvms.pod>
-=item vmsperl list, C<vmsperl-request@newman.upenn.edu>
+=item vmsperl list, C<majordomo@perl.org>
-Put words C<SUBSCRIBE VMSPERL> in message body.
+Put the words C<subscribe vmsperl> in message body.
=item vmsperl on the web, C<http://www.sidhe.org/vmsperl/index.html>
=back
+=head2 VOS
+
+Perl on VOS is discussed in F<README.vos> in the perl distribution.
+Note that 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
+
+or even a mixture of both as in:
+
+ $ perl -ne "print if /perl_setup/i" >system/notices
+
+Note that even though VOS allows the slash character to appear in object
+names, because the VOS port of Perl interprets it as a pathname
+delimiting character, VOS files, directories, or links whose names
+contain a slash character cannot be processed. Such files must be
+renamed before they can be processed by Perl.
+
+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.
+
+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
+can examine the content of the C<@INC> array like so:
+
+ if (grep(/VOS/, @INC)) {
+ print "I'm on a Stratus box!\n";
+ } else {
+ print "I'm not on a Stratus box!\n";
+ die;
+ }
+
+ if (grep(/860/, @INC)) {
+ print "This box is a Stratus XA/R!\n";
+
+ } elsif (grep(/7100/, @INC)) {
+ print "This box is a Stratus HP 7100 or 8000!\n";
+
+ } elsif (grep(/8000/, @INC)) {
+ print "This box is a Stratus HP 8000!\n";
+
+ } else {
+ print "This box is a Stratus 68K...\n";
+ }
+
+Also see:
+
+=over 4
+
+=item L<README.vos>
+
+=item 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 majordomo@list.stratagy.com.
+
+=item VOS Perl on the web at C<http://ftp.stratus.com/pub/vos/vos.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 for IBM Mainframes. Such computers
-use EBCDIC character sets internally (usually Character Code Set ID 00819
-for OS/400 and IBM-1047 for OS/390). Note that on the mainframe perl
-currently works under the "Unix system services for OS/390" (formerly
-known as OpenEdition).
+AS/400 minicomputers as well as OS/390 & VM/ESA for IBM Mainframes. Such
+computers use EBCDIC character sets internally (usually Character Code
+Set ID 00819 for OS/400 and IBM-1047 for OS/390 & VM/ESA). Note that on
+the mainframe perl currently works under the "Unix system services
+for OS/390" (formerly known as OpenEdition) and VM/ESA OpenEdition.
-As of R2.5 of USS for OS/390 that Unix sub-system did not support the
-C<#!> shebang trick for script invocation. Hence, on OS/390 perl scripts
-can executed with a header similar to the following simple script:
+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 ${1+"$@"}'
print "Hello from perl!\n";
+On the AS/400, assuming that 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 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">).
+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 (note that
-C<\r> is the same under both ASCII and EBCDIC):
+C<\r> is the same under both Unix and OS/390 & VM/ESA):
print "Content-type: text/html\r\n\r\n";
The value of C<$^O> on OS/390 is "os390".
+The value of C<$^O> on VM/ESA is "vmesa".
+
Some simple tricks for determining if you are running on an EBCDIC
platform could include any of the following (perhaps all):
if (chr(169) eq 'z') { print "EBCDIC may be spoken here!\n"; }
Note that 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).
+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:
general usage issues for all EBCDIC Perls. Send a message body of
"subscribe perl-mvs" to majordomo@perl.org.
-=item AS/400 Perl information at C<http://as400.rochester.ibm.com>
+=item AS/400 Perl information at C<http://as400.rochester.ibm.com/>
=back
=head2 Acorn RISC OS
-As Acorns use ASCII with newlines (C<\n>) in text files as C<\012> like Unix
-and Unix filename emulation is turned on by default, it is quite likely that
-most simple scripts will work "out of the box". The native filing system is
-modular, and individual filing systems are free to be case sensitive or
-insensitive, usually case preserving. Some native filing systems have name
-length limits which file and directory names are silently truncated to fit -
-scripts should be aware that the standard disc filing system currently has
-a name length limit of B<10> characters, with up to 77 items in a directory,
-but other filing systems may not impose such limitations.
+As Acorns use ASCII with newlines (C<\n>) in text files as C<\012> like
+Unix and Unix filename emulation is turned on by default, it is quite
+likely that most simple scripts will 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::DiscName.$.Directory.Directory.File
-
+ Filesystem#Special_Field::DiskName.$.Directory.Directory.File
+
where
Special_Field is not usually present, but may contain . and $ .
The default filename translation is roughly C<tr|/.|./|;>
-Note that C<"ADFS::HardDisc.$.File" ne 'ADFS::HardDisc.$.File'> and that
-the second stage of $ 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 disc. Writing to a new
-file C<System:Modules> would only be allowed if C<System$Path> contains a
-single item list. The filesystem will also expand system variables in
-filenames if enclosed in angle brackets, so C<E<lt>System$DirE<gt>.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<E<lt>E<gt>>>
-and should be protected when C<open> is used for input.
+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$Path> until a name is made that points to an object on disk.
+Writing to a new file C<System:Modules> would only be allowed if
+C<System$Path> contains a single item list. The filesystem will also
+expand system variables in filenames if enclosed in angle brackets, so
+C<E<lt>System$DirE<gt>.Modules> would look for the file
+S<C<$ENV{'System$Dir'} . 'Modules'>>. The obvious implication of this is
+that B<fully qualified filenames can start with C<E<lt>E<gt>>> and should
+be protected when C<open> is used for input.
Because C<.> was in use as a directory separator and filenames could not
be assumed to be unique after 10 characters, Acorn implemented the C
11charname_.c c.11charname (assuming filesystem truncates at 10)
The Unix emulation library's translation of filenames to native assumes
-that this sort of translation is required, and allows a user defined list of
-known suffixes which it will transpose in this fashion. This may appear
-transparent, but consider that with these rules C<foo/bar/baz.h> and
-C<foo/bar/h/baz> both map to C<foo.bar.h.baz>, and that C<readdir> and
-C<glob> cannot and do not attempt to emulate the reverse mapping. Other '.'s
-in filenames are translated to '/'.
-
-S<RISC OS> has "image files", files that behave as directories. For
-example with suitable software this allows the contents of a zip file to
-be treated as a directory at command line (and therefore script) level,
-with full read-write random access. At present the perl port treats images
-as directories: C<-d> returns true, C<-f> false, and C<unlink> checks to
-ensure that recognised images are empty before deleting them. In theory
-images should never trouble a script, but in practice they may do so if
-the software to deal with an image file is loaded and registered while the
-script is running, as suddenly "files" that it had cached information on
-metamorphose into directories.
-
-As implied above the environment accessed through C<%ENV> is global, and the
-convention is that program specific environment variables are of the form
-C<Program$Name>. Each filing system maintains a current directory, and
-the current filing system's current directory is the B<global> current
-directory. Consequently sociable scripts don't change the current directory
-but rely on full pathnames, and scripts (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).
-
-As native operating system filehandles are global and currently are 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. Run time libraries perform
-command line processing to emulate Unix shell style C<>> redirection, but
-the core operating system is written in assembler and has its own private,
-obscure and somewhat broken convention. All this is further complicated by
-the desire of users to express filenames of the form C<E<lt>Foo$DirE<gt>.Bar> on
-the command line unquoted. (Oh yes, it's run time libraries interpreting the
-quoting convention.) Hence C<``> command output capture has to perform
-a guessing game as to how the command is going to interpret the command line
-so that it can bodge it correctly to capture output. It assumes that a
-string C<E<lt>[^E<lt>E<gt>]+\$[^E<lt>E<gt>]E<gt>> is a reference to an environment
-variable, whereas anything else involving C<E<lt>> or C<E<gt>> is redirection,
-and generally manages to be 99% right. Despite all this the problem remains
-that scripts cannot rely on any Unix tools being available, or that any tools
-found have Unix-like command line arguments.
-
-Extensions and XS are in theory buildable by anyone using free tools. In
-practice many don't as the Acorn platform is used to binary distribution.
-MakeMaker does itself run, but no make currently copes with MakeMaker's
-makefiles! Even if (when) this is fixed os that the lack of a Unix-like
-shell can cause problems with makefile rules, especially lines of the form
-C<cd sdbm && make all> and anything using quoting.
+that this sort of translation is required, and allows a user defined list
+of known suffixes which it will transpose in this fashion. This may
+appear transparent, but consider that with these rules C<foo/bar/baz.h>
+and C<foo/bar/h/baz> both map to C<foo.bar.h.baz>, and that C<readdir> and
+C<glob> cannot and do not attempt to emulate the reverse mapping. Other
+C<.>'s in filenames are translated to C</>.
+
+As implied above the environment accessed through C<%ENV> is global, and
+the convention is that program specific environment variables are of the
+form C<Program$Name>. Each filesystem maintains a current directory,
+and the current filesystem's current directory is the B<global> current
+directory. Consequently, sociable scripts don't change the current
+directory but rely on full pathnames, and scripts (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).
+
+As native operating system filehandles are global and currently are
+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<E<lt>Foo$DirE<gt>.Bar> on the command line unquoted causes problems,
+too: C<``> command output capture has to perform a guessing game. It
+assumes that a string C<E<lt>[^E<lt>E<gt>]+\$[^E<lt>E<gt>]E<gt>> is a
+reference to an environment variable, whereas anything else involving
+C<E<lt>> or C<E<gt>> is redirection, and generally manages to be 99%
+right. Of course, the problem remains that scripts cannot rely on any
+Unix tools being available, or that any tools found have Unix-like command
+line arguments.
+
+Extensions and XS are, in theory, buildable by anyone using free tools.
+In practice, many don't, as users of the Acorn platform are used to binary
+distribution. MakeMaker does run, but no available make currently copes
+with MakeMaker's makefiles; even if/when this is fixed, the lack of a
+Unix-like shell can cause problems with makefile rules, especially lines
+of the form C<cd sdbm && make all>, and anything using quoting.
"S<RISC OS>" is the proper name for the operating system, but the value
in C<$^O> is "riscos" (because we don't like shouting).
-Also see:
-
-=over 4
-
-=item perl list
-
-=back
-
=head2 Other perls
Perl has been ported to a variety of platforms that do not fit into any of
-the above categories. Some, such as AmigaOS, BeOS, QNX, and Plan 9, 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, lynxos, HP-MPE/iX, riscos,
-Tandem Guardian, vos, I<etc.> (yes we know that some of these OSes may fall
-under the Unix category but we are not a standards body.)
+the above categories. 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.)
See also:
=item Novell Netware
-A free Perl 5 based PERL.NLM for Novell Netware is available from
-C<http://www.novell.com/>
+A free perl5-based PERL.NLM for Novell Netware is available in
+precompiled binary and source code form from C<http://www.novell.com/>
+as well as from CPAN.
=back
doubt, consult the platform-specific README files in the Perl source
distribution, and other documentation resources for a given port.
-Be aware, moreover, that even among Unix-ish systems there are variations,
-and not all functions listed here are necessarily available, though
-most usually are.
+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 C<Config.pm>. For example, to check if the platform has the C<lstat>
-call, check C<$Config{'d_lstat'}>. See L<Config> for a full description
-of available variables.
+from the Config module. For example, to check if the platform has the C<lstat>
+call, check C<$Config{'d_lstat'}>. See L<Config> for a full
+description of available variables.
=head2 Alphabetical Listing of Perl Functions
(VMS)
C<-T> and C<-B> are implemented, but might misclassify Mac text files
-with foreign characters; this is the case will all platforms, but
-affects S<Mac OS> a lot. (S<Mac OS>)
+with foreign characters; this is the case will all platforms, but may
+affect S<Mac OS> often. (S<Mac OS>)
C<-x> (or C<-X>) determine if a file ends in one of the executable
suffixes. C<-S> is meaningless. (Win32)
Only good for changing "owner" and "other" read-write access. (S<RISC OS>)
+Access permissions are mapped onto VOS access-control list changes. (VOS)
+
=item chown LIST
-Not implemented. (S<Mac OS>, Win32, Plan9, S<RISC OS>)
+Not implemented. (S<Mac OS>, Win32, Plan9, S<RISC OS>, VOS)
Does nothing, but won't fail. (Win32)
=item chroot
-Not implemented. (S<Mac OS>, Win32, VMS, Plan9, S<RISC OS>)
+Not implemented. (S<Mac OS>, Win32, VMS, Plan9, S<RISC OS>, VOS, VM/ESA)
=item crypt PLAINTEXT,SALT
May not be available if library or source was not provided when building
perl. (Win32)
+Not implemented. (VOS)
+
=item dbmclose HASH
-Not implemented. (VMS, Plan9)
+Not implemented. (VMS, Plan9, VOS)
=item dbmopen HASH,DBNAME,MODE
-Not implemented. (VMS, Plan9)
+Not implemented. (VMS, Plan9, VOS)
=item dump LABEL
Not implemented. (S<Mac OS>)
+Implemented via Spawn. (VM/ESA)
+
=item fcntl FILEHANDLE,FUNCTION,SCALAR
Not implemented. (Win32, VMS)
=item flock FILEHANDLE,OPERATION
-Not implemented (S<Mac OS>, VMS, S<RISC OS>).
+Not implemented (S<Mac OS>, VMS, S<RISC OS>, VOS).
Available only on Windows NT (not on Windows 95). (Win32)
=item fork
-Not implemented. (S<Mac OS>, Win32, AmigaOS, S<RISC OS>)
+Not implemented. (S<Mac OS>, Win32, AmigaOS, S<RISC OS>, VOS, VM/ESA)
=item getlogin
=item getpgrp PID
-Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>)
+Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS)
=item getppid
=item getpriority WHICH,WHO
-Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>)
+Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS, VM/ESA)
=item getpwnam NAME
=item getpwent
-Not implemented. (S<Mac OS>, Win32)
+Not implemented. (S<Mac OS>, Win32, VM/ESA)
=item getgrent
-Not implemented. (S<Mac OS>, Win32, VMS)
+Not implemented. (S<Mac OS>, Win32, VMS, VM/ESA)
=item gethostent
=item endpwent
-Not implemented. (S<Mac OS>, Win32)
+Not implemented. (S<Mac OS>, Win32, VM/ESA)
=item endgrent
-Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>)
+Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VM/ESA)
=item endhostent
Globbing built-in, but only C<*> and C<?> metacharacters are supported.
(S<Mac OS>)
-Features depend on external perlglob.exe or perlglob.bat. May be overridden
-with something like File::DosGlob, which is recommended. (Win32)
+Features depend on external perlglob.exe or perlglob.bat. May be
+overridden with something like File::DosGlob, which is recommended.
+(Win32)
Globbing built-in, but only C<*> and C<?> metacharacters are supported.
-Globbing relies on operating system calls, which may return filenames in
-any order. As most filesystems are case insensitive even "sorted"
-filenames will not be in case sensitive order. (S<RISC OS>)
+Globbing relies on operating system calls, which may return filenames
+in any order. As most filesystems are case-insensitive, even "sorted"
+filenames will not be in case-sensitive order. (S<RISC OS>)
=item ioctl FILEHANDLE,FUNCTION,SCALAR
=item kill LIST
-Not implemented, hence not useful for taint checking. (S<Mac OS>, S<RISC OS>)
+Not implemented, hence not useful for taint checking. (S<Mac OS>,
+S<RISC OS>)
-Available only for process handles returned by the C<system(1, ...)> method of
-spawning a process. (Win32)
+Available only for process handles returned by the C<system(1, ...)>
+method of spawning a process. (Win32)
=item link OLDFILE,NEWFILE
Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>)
+Link count not updated because hard links are not quite that hard
+(They are sort of half-way between hard and soft links). (AmigaOS)
+
=item lstat FILEHANDLE
=item lstat EXPR
=item msgrcv ID,VAR,SIZE,TYPE,FLAGS
-Not implemented. (S<Mac OS>, Win32, VMS, Plan9, S<RISC OS>)
+Not implemented. (S<Mac OS>, Win32, VMS, Plan9, S<RISC OS>, VOS)
=item open FILEHANDLE,EXPR
Not implemented. (S<Mac OS>)
+Very limited functionality. (MiNT)
+
=item readlink EXPR
=item readlink
=item semop KEY,OPSTRING
-Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>)
+Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS)
=item setpgrp PID,PGRP
-Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>)
+Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS)
=item setpriority WHICH,WHO,PRIORITY
-Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>)
+Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS)
=item setsockopt SOCKET,LEVEL,OPTNAME,OPTVAL
=item shmwrite ID,STRING,POS,SIZE
-Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>)
+Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS)
=item socketpair SOCKET1,SOCKET2,DOMAIN,TYPE,PROTOCOL
-Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>)
+Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS, VM/ESA)
=item stat FILEHANDLE
=item syscall LIST
-Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>)
+Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS, VM/ESA)
+
+=item sysopen FILEHANDLE,FILENAME,MODE,PERMS
+
+The traditional "0", "1", and "2" MODEs are implemented with different
+numeric values on some systems. The flags exported by C<Fcntl>
+(O_RDONLY, O_WRONLY, O_RDWR) should work everywhere though. (S<Mac
+OS>, OS/390, VM/ESA)
=item system LIST
I<scalar> will call the native command line direct and no such emulation
of a child Unix program will exists. Mileage B<will> vary. (S<RISC OS>)
+Far from being POSIX compliant. Because there may be no underlying
+/bin/sh tries to work around the problem by forking and execing the
+first token in its argument string. Handles basic redirection
+("E<lt>" or "E<gt>") on its own behalf. (MiNT)
+
=item times
Only the first entry returned is nonzero. (S<Mac OS>)
Not implemented. (VMS)
+Truncation to zero-length only. (VOS)
+
+If a FILEHANDLE is supplied, it must be writable and opened in append
+mode (i.e., use C<open(FH, '>>filename')>
+or C<sysopen(FH,...,O_APPEND|O_RDWR)>. If a filename is supplied, it
+should not be held open elsewhere. (Win32)
+
=item umask EXPR
=item umask
Returns undef where unavailable, as of version 5.005.
+C<umask()> works but the correct permissions are only set when the file
+is finally close()d. (AmigaOS)
+
=item utime LIST
Only the modification time is updated. (S<Mac OS>, VMS, S<RISC OS>)
-May not behave as expected. (Win32)
+May not behave as expected. Behavior depends on the C runtime
+library's implementation of utime(), and the filesystem being
+used. The FAT filesystem typically does not support an "access
+time" field, and it may limit timestamps to a granularity of
+two seconds. (Win32)
=item wait
=item waitpid PID,FLAGS
-Not implemented. (S<Mac OS>)
+Not implemented. (S<Mac OS>, VOS)
Can only be applied to process handles returned for processes spawned
using C<system(1, ...)>. (Win32)
=over 4
-=item 1.30, 03 August 1998
+=item v1.41, 19 May 1999
+
+Lots more little changes to formatting and content.
+
+Added a bunch of <$^O> and related values
+for various platforms; fixed mail and web addresses, and added
+and changed miscellaneous notes. (Peter Prymmer)
+
+=item v1.40, 11 April 1999
+
+Miscellaneous changes.
+
+=item v1.39, 11 February 1999
+
+Changes from Jarkko and EMX URL fixes Michael Schwern. Additional
+note about newlines added.
+
+=item v1.38, 31 December 1998
+
+More changes from Jarkko.
+
+=item v1.37, 19 December 1998
+
+More minor changes. Merge two separate version 1.35 documents.
+
+=item v1.36, 9 September 1998
+
+Updated for Stratus VOS. Also known as version 1.35.
+
+=item v1.35, 13 August 1998
+
+Integrate more minor changes, plus addition of new sections under
+L<"ISSUES">: L<"Numbers endianness and Width">,
+L<"Character sets and character encoding">,
+L<"Internationalisation">.
+
+=item v1.33, 06 August 1998
+
+Integrate more minor changes.
+
+=item v1.32, 05 August 1998
+
+Integrate more minor changes.
+
+=item v1.30, 03 August 1998
Major update for RISC OS, other minor changes.
-=item 1.23, 10 July 1998
+=item v1.23, 10 July 1998
First public release with perl5.005.
=head1 AUTHORS / CONTRIBUTORS
-Chris Nandor E<lt>pudge@pobox.comE<gt>,
-Gurusamy Sarathy E<lt>gsar@umich.eduE<gt>,
-Peter Prymmer E<lt>pvhp@forte.comE<gt>,
+Abigail E<lt>abigail@fnx.comE<gt>,
+Charles Bailey E<lt>bailey@newman.upenn.eduE<gt>,
+Graham Barr E<lt>gbarr@pobox.comE<gt>,
Tom Christiansen E<lt>tchrist@perl.comE<gt>,
-Nathan Torkington E<lt>gnat@frii.comE<gt>,
-Paul Moore E<lt>Paul.Moore@uk.origin-it.comE<gt>,
-Matthias Neercher E<lt>neeri@iis.ee.ethz.chE<gt>,
-Charles Bailey E<lt>bailey@genetics.upenn.eduE<gt>,
+Nicholas Clark E<lt>Nicholas.Clark@liverpool.ac.ukE<gt>,
+Andy Dougherty E<lt>doughera@lafcol.lafayette.eduE<gt>,
+Dominic Dunlop E<lt>domo@vo.luE<gt>,
+Neale Ferguson E<lt>neale@mailbox.tabnsw.com.auE<gt>
+Paul Green E<lt>Paul_Green@stratus.comE<gt>,
+M.J.T. Guy E<lt>mjtg@cus.cam.ac.ukE<gt>,
+Jarkko Hietaniemi E<lt>jhi@iki.fi<gt>,
Luther Huffman E<lt>lutherh@stratcom.comE<gt>,
-Gary Ng E<lt>71564.1743@CompuServe.COME<gt>,
Nick Ing-Simmons E<lt>nick@ni-s.u-net.comE<gt>,
-Paul J. Schinder E<lt>schinder@pobox.comE<gt>,
+Andreas J. KE<ouml>nig E<lt>koenig@kulturbox.deE<gt>,
+Markus Laker E<lt>mlaker@contax.co.ukE<gt>,
+Andrew M. Langmead E<lt>aml@world.std.comE<gt>,
+Paul Moore E<lt>Paul.Moore@uk.origin-it.comE<gt>,
+Chris Nandor E<lt>pudge@pobox.comE<gt>,
+Matthias Neeracher E<lt>neeri@iis.ee.ethz.chE<gt>,
+Gary Ng E<lt>71564.1743@CompuServe.COME<gt>,
Tom Phoenix E<lt>rootbeer@teleport.comE<gt>,
-Hugo van der Sanden E<lt>h.sanden@elsevier.nlE<gt>,
-Dominic Dunlop E<lt>domo@vo.luE<gt>,
+Peter Prymmer E<lt>pvhp@forte.comE<gt>,
+Hugo van der Sanden E<lt>hv@crypt0.demon.co.ukE<gt>,
+Gurusamy Sarathy E<lt>gsar@umich.eduE<gt>,
+Paul J. Schinder E<lt>schinder@pobox.comE<gt>,
+Michael G Schwern E<lt>schwern@pobox.comE<gt>,
Dan Sugalski E<lt>sugalskd@ous.eduE<gt>,
-Andreas J. Koenig E<lt>koenig@kulturbox.deE<gt>,
-Andrew M. Langmead E<lt>aml@world.std.comE<gt>,
-Andy Dougherty E<lt>doughera@lafcol.lafayette.eduE<gt>,
-Abigail E<lt>abigail@fnx.comE<gt>,
-Nicholas Clark E<lt>Nicholas.Clark@liverpool.ac.ukE<gt>.
+Nathan Torkington E<lt>gnat@frii.comE<gt>.
-This document is maintained by Chris Nandor.
+This document is maintained by Chris Nandor
+E<lt>pudge@pobox.comE<gt>.
=head1 VERSION
-Version 1.30, last modified 03 August 1998.
-
+Version 1.41, last modified 19 May 1999
projects / p5sagit/p5-mst-13.2.git / blobdiff