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diff --git a/contrib/perl5/pod/perlport.pod b/contrib/perl5/pod/perlport.pod deleted file mode 100644 index 9ae89e0..0000000 --- a/contrib/perl5/pod/perlport.pod +++ /dev/null @@ -1,2085 +0,0 @@ -=head1 NAME - -perlport - Writing portable Perl - -=head1 DESCRIPTION - -Perl runs on numerous operating systems. While most of them share -much in common, they also have their own unique features. - -This document is meant to help you to find out what constitutes portable -Perl code. That way once you make a 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 one particular -type of computer and taking advantage of a full range of them. -Naturally, as you broaden your range and become more diverse, the -common factors drop, and you are left with an increasingly smaller -area 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 under which part of the tradeoff curve you -want to operate. Specifically, you must decide whether it is -important that the task that you are coding have the full generality -of being portable, or whether to just get the job done right now. -This is the hardest choice to be made. The rest is easy, because -Perl provides many 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 and sacrifice to do that. The product of portability -and convenience may be a constant. You have been warned. - -Be aware of two important points: - -=over 4 - -=item Not all Perl programs have to be portable - -There is no reason you should not use Perl as a language to glue Unix -tools together, or to prototype a Macintosh application, or to manage the -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 Nearly all of Perl already 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 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 commonly done -using a whole range of platforms, think about writing portable -code. That way, you don't sacrifice much by way of the implementation -choices you can avail yourself of, and at the same time you can give -your users lots of platform choices. On the other hand, when you have to -take advantage of some unique feature of a particular platform, as is -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, you -may need to consider only 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 -built-in 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 -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">). - -=head1 ISSUES - -=head2 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 type of DOSish I/O uses C<\015\012>, -and S<Mac OS> uses C<\015>. - -Perl uses C<\n> to represent the "logical" newline, where what 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>, 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 $/ to the appropriate value for your file format -before using chomp(). - -Because of the "text" mode translation, DOSish perls have limitations -in using C<seek> and C<tell> on a file accessed in "text" mode. -Stick to C<seek>-ing to locations you got from C<tell> (and no -others), and you are usually free to use C<seek> and C<tell> even -in "text" mode. Using C<seek> or C<tell> or other file operations -may be non-portable. If you use C<binmode> on a file, however, you -can usually C<seek> and C<tell> with arbitrary values in safety. - -A common misconception in socket programming is that C<\n> eq C<\012> -everywhere. When using protocols such as common Internet protocols, -C<\012> and C<\015> are called for specifically, and the values of -the logical C<\n> and C<\r> (carriage return) are not reliable. - - print SOCKET "Hi there, client!\r\n"; # WRONG - print SOCKET "Hi there, client!\015\012"; # RIGHT - -However, using C<\015\012> (or C<\cM\cJ>, or C<\x0D\x0A>) can be tedious -and unsightly, as well as confusing to those maintaining the code. As -such, the Socket module supplies the Right Thing for those who want it. - - use Socket qw(:DEFAULT :crlf); - print SOCKET "Hi there, client!$CRLF" # RIGHT - -When reading from a socket, remember that the default input record -separator C<$/> is C<\n>, but robust socket code will recognize as -either C<\012> or C<\015\012> as end of line: - - while (<SOCKET>) { - # ... - } - -Because both CRLF and LF end in LF, the input record separator can -be set to LF and any CR stripped later. Better to write: - - use Socket qw(:DEFAULT :crlf); - local($/) = LF; # not needed if $/ is already \012 - - while (<SOCKET>) { - s/$CR?$LF/\n/; # not sure if socket uses LF or CRLF, OK - # s/\015?\012/\n/; # same thing - } - -This example is preferred over the previous one--even for Unix -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 sometimes translate newlines before -returning the data, if they've not yet been translated to the local -newline representation. A single line of code will often 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 - -The Unix column assumes that you are not accessing a serial line -(like a tty) in canonical mode. If you are, then CR on input becomes -"\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. - -=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 today). This affects your programs when they attempt to transfer -numbers in binary format from one CPU architecture to another, -usually either "live" via network connection, or by storing the -numbers to secondary storage such as a disk file or tape. - -Conflicting storage orders make utter mess out of the numbers. If a -little-endian host (Intel, VAX) stores 0x12345678 (305419896 in -decimal), a big-endian host (Motorola, Sparc, PA) reads it as -0x78563412 (2018915346 in decimal). Alpha and MIPS can be either: -Digital/Compaq used/uses them in little-endian mode; SGI/Cray uses -them in big-endian mode. To avoid this problem in network (socket) -connections use the C<pack> and C<unpack> formats C<n> and C<N>, the -"network" orders. These are guaranteed to be portable. - -You can explore the endianness of your platform by unpacking a -data structure packed in native format such as: - - print unpack("h*", pack("s2", 1, 2)), "\n"; - # '10002000' on e.g. Intel x86 or Alpha 21064 in little-endian mode - # '00100020' on e.g. Motorola 68040 - -If you need to distinguish between endian architectures you could use -either of the variables set like so: - - $is_big_endian = unpack("h*", pack("s", 1)) =~ /01/; - $is_little_endian = unpack("h*", pack("s", 1)) =~ /^1/; - -Differing 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 else consider using modules like Data::Dumper (included in -the standard distribution as of Perl 5.005) and Storable. Keeping -all data as text significantly simplifies matters. - -=head2 Files and Filesystems - -Most platforms these days structure files in a hierarchical fashion. -So, it is reasonably safe to assume that all platforms support the -notion of a "path" to uniquely identify a file on the system. How -that path is really written, though, differs considerably. - -Although similar, file path specifications differ between Unix, -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 elegant 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::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' - # on VMS, '[.temp]file.txt' - -File::Spec is available in the standard distribution as of version -5.004_05. File::Spec::Functions is only in File::Spec 0.7 and later, -and some versions of perl come with version 0.6. If File::Spec -is not updated to 0.7 or later, you must use the object-oriented -interface from File::Spec (or upgrade File::Spec). - -In general, production code should not have file paths hardcoded. -Making them user-supplied or read from a configuration file is -better, keeping in mind that file path syntax varies on different -machines. - -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 File::Basename from the standard distribution, which -splits a pathname into pieces (base filename, full path to directory, -and file suffix). - -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 particular -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 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, then 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. 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. - -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. -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. - - open(FILE, "< $existing_file") or die $!; - -If filenames might use strange characters, it is safest to open it -with C<sysopen> instead of C<open>. C<open> is magic and can -translate characters like C<< > >>, C<< < >>, and C<|>, which may -be the wrong thing to do. (Sometimes, though, it's the right thing.) - -=head2 System Interaction - -Not all platforms provide a command line. These are usually platforms -that rely primarily on a Graphical User Interface (GUI) for user -interaction. A program requiring a command line interface might -not work everywhere. This is probably for the user of the program -to deal with, so don't stay up late worrying about it. - -Some platforms can't delete or rename files held open by the system. -Remember to C<close> files when you are done with them. Don't -C<unlink> or C<rename> an open file. Don't C<tie> or C<open> a -file already tied or opened; C<untie> or C<close> it first. - -Don't open the same file more than once at a time for writing, as some -operating systems put mandatory locks on such files. - -Don't count on a specific environment variable existing in C<%ENV>. -Don't count on C<%ENV> entries being case-sensitive, or even -case-preserving. Don't try to clear %ENV by saying C<%ENV = ();>, or, -if you really have to, make it conditional on C<$^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. - -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 -directories. - -Don't count on specific values of C<$!>. - -=head2 Interprocess Communication (IPC) - -In general, don't directly access the system in code meant to be -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 perl hacker worth being. - -Commands that launch external processes are generally supported on -most platforms (though many of them do not support any type of -forking). The problem with using them arises from what you invoke -them on. External tools are often named differently on different -platforms, may not be available in the same location, might accept -different arguments, can behave differently, and often present their -results in a platform-dependent way. Thus, you should seldom depend -on them to produce consistent results. (Then again, if you're calling -I<netstat -a>, you probably don't expect it to run on both Unix and CP/M.) - -One especially common bit of Perl code is opening a pipe to B<sendmail>: - - open(MAIL, '|/usr/lib/sendmail -t') - or die "cannot fork sendmail: $!"; - -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 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 Unix System V IPC (C<msg*(), sem*(), shm*()>) is not available -even on all Unix platforms. - -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). - -=head2 External Subroutines (XS) - -XS code can usually be made to work with any platform, but dependent -libraries, header files, etc., might not be readily available or -portable, or the XS code itself might be platform-specific, just as Perl -code might be. If the libraries and headers are portable, then it is -normally reasonable to make sure the XS code is portable, too. - -A different type of portability issue arises when 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 some of those. Writing purely in Perl is an easier way to -achieve portability. - -=head2 Standard Modules - -In general, the standard modules work across platforms. Notable -exceptions are the CPAN module (which currently makes connections to external -programs that may not be available), platform-specific modules (like -ExtUtils::MM_VMS), and DBM modules. - -There is no one DBM module available on all platforms. -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 -AnyDBM_File will use whichever module it can find. Of course, then -the code needs to be fairly strict, dropping to the greatest common -factor (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. - -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. - -When calculating specific times, such as for tests in time or date modules, -it may be appropriate to calculate an offset for the epoch. - - require Time::Local; - $offset = Time::Local::timegm(0, 0, 0, 1, 0, 70); - -The value for C<$offset> in Unix will be C<0>, but in Mac OS will be -some large number. C<$offset> can then be added to a Unix time value -to get what should be the proper value on any system. - -=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'. - -=head2 Internationalisation - -If you may assume POSIX (a rather large assumption), you may read -more about the POSIX locale system from 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--amongst 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 I<especially> mindful -of avoiding wasteful constructs such as: - - # NOTE: this is no longer "bad" in perl5.005 - for (0..10000000) {} # bad - for (my $x = 0; $x <= 10000000; ++$x) {} # good - - @lines = <VERY_LARGE_FILE>; # bad - - while (<FILE>) {$file .= $_} # sometimes bad - $file = join('', <FILE>); # better - -The last two constructs may appear unintuitive to most people. The -first repeatedly grows a string, whereas the second allocates a -large chunk of memory in one go. On some systems, the second is -more efficient that the first. - -=head2 Security - -Most multi-user platforms provide basic levels of security, usually -implemented at the filesystem level. Some, however, do -not--unfortunately. Thus the notion of user id, or "home" directory, -or even the state of being logged-in, may be unrecognizable on many -platforms. If you write programs that are security-conscious, it -is usually best to know what type of system you will be running -under so that you can write code explicitly for that platform (or -class of platforms). - -=head2 Style - -For those times when it is necessary to have platform-specific code, -consider keeping the platform-specific code in one place, making porting -to other platforms easier. Use the Config module and the special -variable C<$^O> to differentiate platforms, as described in -L<"PLATFORMS">. - -Be careful in the tests you supply with your module or programs. -Module code may be fully portable, but its tests might not be. This -often happens when tests spawn off other processes or call external -programs to aid in the testing, or when (as noted above) the tests -assume certain things about the filesystem and paths. Be careful -not to depend on a specific output style for errors, such as when -checking C<$!> after an system call. Some platforms expect a certain -output format, and perl on those platforms may have been adjusted -accordingly. Most specifically, don't anchor a regex when testing -an error value. - -=head1 CPAN Testers - -Modules uploaded to CPAN are tested by a variety of volunteers on -different platforms. These CPAN testers are notified by mail of each -new upload, and reply to the list with PASS, FAIL, NA (not applicable to -this platform), or UNKNOWN (unknown), along with any relevant notations. - -The purpose of the testing is twofold: one, to help developers fix any -problems in their code that crop up because of lack of testing on other -platforms; two, to provide users with information about whether -a given module works on a given platform. - -=over 4 - -=item Mailing list: cpan-testers@perl.org - -=item Testing results: http://testers.cpan.org/ - -=back - -=head1 PLATFORMS - -As of version 5.002, Perl is built with a C<$^O> variable that -indicates the operating system it was built on. This was implemented -to help speed up code that would otherwise have to C<use Config> -and use the value of C<$Config{osname}>. Of course, to get more -detailed information about the system, looking into C<%Config> is -certainly recommended. - -C<%Config> cannot always be trusted, however, because it was built -at compile time. If perl was built in one place, then transferred -elsewhere, some values may be wrong. The values may even have been -edited after the fact. - -=head2 Unix - -Perl works on a bewildering variety of Unix and Unix-like platforms (see -e.g. most of the files in the F<hints/> directory in the source code kit). -On most of these systems, the value of C<$^O> (hence C<$Config{'osname'}>, -too) is determined either by lowercasing and stripping punctuation from the -first field of the string returned by typing C<uname -a> (or a similar command) -at the shell prompt or by testing the file system for the presence of -uniquely named files such as a kernel or header file. Here, for example, -are a few of the more popular Unix flavors: - - uname $^O $Config{'archname'} - -------------------------------------------- - AIX aix aix - BSD/OS bsdos i386-bsdos - dgux dgux AViiON-dgux - DYNIX/ptx dynixptx i386-dynixptx - FreeBSD freebsd freebsd-i386 - Linux linux arm-linux - Linux linux i386-linux - Linux linux i586-linux - Linux linux ppc-linux - HP-UX hpux PA-RISC1.1 - IRIX irix irix - Mac OS X rhapsody rhapsody - MachTen PPC machten powerpc-machten - NeXT 3 next next-fat - NeXT 4 next OPENSTEP-Mach - openbsd openbsd i386-openbsd - OSF1 dec_osf alpha-dec_osf - reliantunix-n svr4 RM400-svr4 - SCO_SV sco_sv i386-sco_sv - SINIX-N svr4 RM400-svr4 - sn4609 unicos CRAY_C90-unicos - sn6521 unicosmk t3e-unicosmk - sn9617 unicos CRAY_J90-unicos - SunOS solaris sun4-solaris - SunOS solaris i86pc-solaris - SunOS4 sunos sun4-sunos - -Because the value of C<$Config{archname}> may depend on the -hardware architecture, it can vary more than the value of C<$^O>. - -=head2 DOS and Derivatives - -Perl has long been ported to Intel-style microcomputers running under -systems like PC-DOS, MS-DOS, OS/2, and most Windows platforms you can -bring yourself to mention (except for Windows CE, if you count that). -Users familiar with I<COMMAND.COM> or I<CMD.EXE> style shells should -be aware that each of these file specifications may have subtle -differences: - - $filespec0 = "c:/foo/bar/file.txt"; - $filespec1 = "c:\\foo\\bar\\file.txt"; - $filespec2 = 'c:\foo\bar\file.txt'; - $filespec3 = 'c:\\foo\\bar\\file.txt'; - -System calls accept either C</> or C<\> as the path separator. -However, many command-line utilities of DOS vintage treat C</> as -the option prefix, so may get confused by filenames containing C</>. -Aside from calling any external programs, C</> will work just fine, -and probably better, as it is more consistent with popular usage, -and avoids the problem of remembering what to backwhack and what -not to. - -The DOS FAT filesystem can accommodate only "8.3" style filenames. Under -the "case-insensitive, but case-preserving" HPFS (OS/2) and NTFS (NT) -filesystems you may have to be careful about case returned with functions -like C<readdir> or used with functions like C<open> or C<opendir>. - -DOS also treats several filenames as special, such as AUX, PRN, -NUL, CON, COM1, LPT1, LPT2, etc. Unfortunately, sometimes these -filenames won't even work if you include an explicit directory -prefix. It is best to avoid such filenames, if you want your code -to be portable to DOS and its derivatives. It's hard to know what -these all are, unfortunately. - -Users of these operating systems may also wish to make use of -scripts such as I<pl2bat.bat> or I<pl2cmd> to -put wrappers around your scripts. - -Newline (C<\n>) is translated as C<\015\012> by STDIO when reading from -and writing to files (see L<"Newlines">). C<binmode(FILEHANDLE)> -will keep C<\n> translated as C<\012> for that filehandle. Since it is a -no-op on other systems, C<binmode> should be used for cross-platform code -that deals with binary data. That's assuming you realize in advance -that your data is in binary. General-purpose programs should -often assume nothing about their data. - -The C<$^O> variable and the C<$Config{archname}> values for various -DOSish perls are as follows: - - OS $^O $Config{'archname'} - -------------------------------------------- - MS-DOS dos - PC-DOS dos - OS/2 os2 - Windows 95 MSWin32 MSWin32-x86 - Windows 98 MSWin32 MSWin32-x86 - Windows NT MSWin32 MSWin32-x86 - Windows NT MSWin32 MSWin32-ALPHA - Windows NT MSWin32 MSWin32-ppc - Cygwin cygwin - -The various MSWin32 Perl's can distinguish the OS they are running on -via the value of the fifth element of the list returned from -Win32::GetOSVersion(). For example: - - if ($^O eq 'MSWin32') { - my @os_version_info = Win32::GetOSVersion(); - print +('3.1','95','NT')[$os_version_info[4]],"\n"; - } - -Also see: - -=over 4 - -=item * - -The djgpp environment for DOS, http://www.delorie.com/djgpp/ -and L<perldos>. - -=item * - -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>. - -=item * - -Build instructions for Win32 in L<perlwin32>, or under the Cygnus environment -in L<perlcygwin>. - -=item * - -The C<Win32::*> modules in L<Win32>. - -=item * - -The ActiveState Pages, http://www.activestate.com/ - -=item * - -The Cygwin environment for Win32; F<README.cygwin> (installed -as L<perlcygwin>), http://www.cygwin.com/ - -=item * - -The U/WIN environment for Win32, -http://www.research.att.com/sw/tools/uwin/ - -=item * - -Build instructions for OS/2, L<perlos2> - -=back - -=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. - -Directories are specified as: - - volume:folder:file for absolute pathnames - volume:folder: for absolute pathnames - :folder:file for relative pathnames - :folder: for relative pathnames - :file for relative pathnames - file for relative pathnames - -Files are stored in the directory in alphabetical order. Filenames are -limited to 31 characters, and may include any character except for -null and C<:>, which is reserved as the path separator. - -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 -like the following, which brings up a dialog box asking for the command -line arguments. - - if (!@ARGV) { - @ARGV = split /\s+/, MacPerl::Ask('Arguments?'); - } - -A MacPerl script saved as a "droplet" will populate C<@ARGV> with the full -pathnames of the files dropped onto the script. - -Mac users can run programs under a type of command line interface -under MPW (Macintosh Programmer's Workshop, a free development -environment from Apple). MacPerl was first introduced as an MPW -tool, and MPW can be used like a shell: - - 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 programs to use -C<system>, backticks, and piped C<open>. - -"S<Mac OS>" is the proper name for the operating system, but the value -in C<$^O> is "MacOS". To determine architecture, version, or whether -the application or MPW tool version is running, check: - - $is_app = $MacPerl::Version =~ /App/; - $is_tool = $MacPerl::Version =~ /MPW/; - ($version) = $MacPerl::Version =~ /^(\S+)/; - $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 few patches). Full support for these -is slated for perl 5.6. - -Also see: - -=over 4 - -=item * - -The MacPerl Pages, http://www.macperl.com/ . - -=item * - -The MacPerl mailing lists, http://www.macperl.org/ . - -=item * - -MacPerl Module Porters, http://pudge.net/mmp/ . - -=back - -=head2 VMS - -Perl on VMS is discussed in L<perlvms> in the perl distribution. -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 - $ perl -ne "print if /perl_setup/i" /sys$login/login.com - -but not a mixture of both as in: - - $ perl -ne "print if /perl_setup/i" sys$login:/login.com - Can't open sys$login:/login.com: file specification syntax error - -Interacting with Perl from the Digital Command Language (DCL) shell -often requires a different set of quotation marks than Unix shells do. -For example: - - $ perl -e "print ""Hello, world.\n""" - Hello, world. - -There are several ways to wrap your perl scripts in DCL F<.COM> files, if -you are so inclined. For example: - - $ write sys$output "Hello from DCL!" - $ if p1 .eqs. "" - $ then perl -x 'f$environment("PROCEDURE") - $ else perl -x - 'p1 'p2 'p3 'p4 'p5 'p6 'p7 'p8 - $ deck/dollars="__END__" - #!/usr/bin/perl - - print "Hello from Perl!\n"; - - __END__ - $ endif - -Do take care with C<$ ASSIGN/nolog/user SYS$COMMAND: SYS$INPUT> if your -perl-in-DCL script expects to do things like C<< $read = <STDIN>; >>. - -Filenames are in the format "name.extension;version". The maximum -length for filenames is 39 characters, and the maximum length for -extensions is also 39 characters. Version is a number from 1 to -32767. Valid characters are C</[A-Z0-9$_-]/>. - -VMS's RMS filesystem is case-insensitive and does not preserve case. -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')>). - -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 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 opened. It could -be C<\015>, C<\012>, C<\015\012>, or nothing. The VMS::Stdio module -provides access to the special fopen() requirements of files with unusual -attributes on VMS. - -TCP/IP stacks are optional on VMS, so socket routines might not be -implemented. UDP sockets may not be supported. - -The value of C<$^O> on OpenVMS is "VMS". 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(/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. Although 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 * - -F<README.vms> (installed as L<README_vms>), L<perlvms> - -=item * - -vmsperl list, majordomo@perl.org - -(Put the words C<subscribe vmsperl> in message body.) - -=item * - -vmsperl on the web, http://www.sidhe.org/vmsperl/index.html - -=back - -=head2 VOS - -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 - -or even a mixture of both as in: - - $ 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 -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. 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. - -The value of C<$^O> on VOS is "VOS". To determine the architecture that -you are running on without resorting to loading all of C<%Config> you -can examine the content of the @INC array like so: - - if ($^O =~ /VOS/) { - 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 8xxx!\n"; - - } elsif (grep(/8000/, @INC)) { - print "This box is a Stratus HP 8xxx!\n"; - - } else { - print "This box is a Stratus 68K!\n"; - } - -Also see: - -=over 4 - -=item * - -F<README.vos> - -=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 majordomo@list.stratagy.com. - -=item * - -VOS Perl on the web at 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, 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. - -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 $Config{'archname'} - -------------------------------------------- - OS/390 os390 os390 - OS400 os400 os400 - POSIX-BC posix-bc BS2000-posix-bc - VM/ESA vmesa vmesa - -Some simple tricks for determining if you are running on an EBCDIC -platform could include any of the following (perhaps all): - - if ("\t" eq "\05") { print "EBCDIC may be spoken here!\n"; } - - if (ord('A') == 193) { print "EBCDIC may be spoken here!\n"; } - - if (chr(169) eq 'z') { print "EBCDIC may be spoken here!\n"; } - -One thing you may not want to rely on is the EBCDIC encoding -of punctuation characters since these may differ from code page to code -page (and once your module or script is rumoured to work with EBCDIC, -folks will want it to work with all EBCDIC character sets). - -Also see: - -=over 4 - -=item * - -* - -L<perlos390>, F<README.os390>, F<perlbs2000>, F<README.vmesa>, -L<perlebcdic>. - -=item * - -The perl-mvs@perl.org list is for discussion of porting issues as well as -general usage issues for all EBCDIC Perls. Send a message body of -"subscribe perl-mvs" to majordomo@perl.org. - -=item * - -AS/400 Perl information at -http://as400.rochester.ibm.com/ -as well as on CPAN in the F<ports/> directory. - -=back - -=head2 Acorn RISC OS - -Because Acorns use ASCII with newlines (C<\n>) in text files as C<\012> like -Unix, and because Unix filename emulation is turned on by default, -most simple scripts will probably work "out of the box". The native -filesystem is modular, and individual filesystems are free to be -case-sensitive or insensitive, and are usually case-preserving. Some -native filesystems have name length limits, which file and directory -names are silently truncated to fit. Scripts should be aware that the -standard filesystem currently has a name length limit of B<10> -characters, with up to 77 items in a directory, but other filesystems -may not impose such limitations. - -Native filenames are of the form - - Filesystem#Special_Field::DiskName.$.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 $Config{'archname'} - ------------------------------------------ - Amiga DOS amigaos m68k-amigos - MPE/iX mpeix PA-RISC1.1 - -See also: - -=over 4 - -=item * - -Amiga, F<README.amiga> (installed as L<perlamiga>). - -=item * - -Atari, F<README.mint> and Guido Flohr's web page -http://stud.uni-sb.de/~gufl0000/ - -=item * - -Be OS, F<README.beos> - -=item * - -HP 300 MPE/iX, F<README.mpeix> and Mark Bixby's web page -http://www.bixby.org/mark/perlix.html - -=item * - -A free perl5-based PERL.NLM for Novell Netware is available in -precompiled binary and source code form from http://www.novell.com/ -as well as from CPAN. - -=item * - -Plan 9, F<README.plan9> - -=back - -=head1 FUNCTION IMPLEMENTATIONS - -Listed below are functions that are either completely unimplemented -or else have been implemented differently on various platforms. -Following each description will be, in parentheses, a list of -platforms that the description applies to. - -The list may well be incomplete, or even wrong in some places. When -in doubt, consult the platform-specific README files in the Perl -source distribution, and any other documentation resources accompanying -a given port. - -Be aware, moreover, that even among Unix-ish systems there are variations. - -For many functions, you can also query C<%Config>, exported by -default from the Config module. For example, to check whether the -platform has the C<lstat> call, check C<$Config{d_lstat}>. See -L<Config> for a full description of available variables. - -=head2 Alphabetical Listing of Perl Functions - -=over 8 - -=item -X FILEHANDLE - -=item -X EXPR - -=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 data fork -plus resource fork. (S<Mac OS>). - -C<-s> by name on an open file will return the space reserved on disk, -rather than the current extent. C<-s> on an open filehandle returns the -current size. (S<RISC OS>) - -C<-R>, C<-W>, C<-X>, C<-O> are indistinguishable from C<-r>, C<-w>, -C<-x>, C<-o>. (S<Mac OS>, Win32, VMS, S<RISC OS>) - -C<-b>, C<-c>, C<-k>, C<-g>, C<-p>, C<-u>, C<-A> are not implemented. -(S<Mac OS>) - -C<-g>, C<-k>, C<-l>, C<-p>, C<-u>, C<-A> are not particularly meaningful. -(Win32, VMS, S<RISC OS>) - -C<-d> is true if passed a device spec without an explicit directory. -(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 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) - -C<-x> (or C<-X>) determine if a file has an executable file type. -(S<RISC OS>) - -=item alarm SECONDS - -=item alarm - -Not implemented. (Win32) - -=item binmode FILEHANDLE - -Meaningless. (S<Mac OS>, S<RISC OS>) - -Reopens file and restores pointer; if function fails, underlying -filehandle may be closed, or pointer may be in a different position. -(VMS) - -The value returned by C<tell> may be affected after the call, and -the filehandle may be flushed. (Win32) - -=item chmod LIST - -Only limited meaning. Disabling/enabling write permission is mapped to -locking/unlocking the file. (S<Mac OS>) - -Only good for changing "owner" read-write access, "group", and "other" -bits are 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>, VOS) - -Does nothing, but won't fail. (Win32) - -=item chroot FILENAME - -=item chroot - -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, VOS) - -=item dbmopen HASH,DBNAME,MODE - -Not implemented. (VMS, Plan9, VOS) - -=item dump LABEL - -Not useful. (S<Mac OS>, S<RISC OS>) - -Not implemented. (Win32) - -Invokes VMS debugger. (VMS) - -=item exec LIST - -Not implemented. (S<Mac OS>) - -Implemented via Spawn. (VM/ESA) - -Does not automatically flush output handles on some platforms. -(SunOS, Solaris, HP-UX) - -=item fcntl FILEHANDLE,FUNCTION,SCALAR - -Not implemented. (Win32, VMS) - -=item flock FILEHANDLE,OPERATION - -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>, AmigaOS, S<RISC OS>, VOS, VM/ESA) - -Emulated using multiple interpreters. See L<perlfork>. (Win32) - -Does not automatically flush output handles on some platforms. -(SunOS, Solaris, HP-UX) - -=item getlogin - -Not implemented. (S<Mac OS>, S<RISC OS>) - -=item getpgrp PID - -Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS) - -=item getppid - -Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>) - -=item getpriority WHICH,WHO - -Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS, VM/ESA) - -=item getpwnam NAME - -Not implemented. (S<Mac OS>, Win32) - -Not useful. (S<RISC OS>) - -=item getgrnam NAME - -Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>) - -=item getnetbyname NAME - -Not implemented. (S<Mac OS>, Win32, Plan9) - -=item getpwuid UID - -Not implemented. (S<Mac OS>, Win32) - -Not useful. (S<RISC OS>) - -=item getgrgid GID - -Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>) - -=item getnetbyaddr ADDR,ADDRTYPE - -Not implemented. (S<Mac OS>, Win32, Plan9) - -=item getprotobynumber NUMBER - -Not implemented. (S<Mac OS>) - -=item getservbyport PORT,PROTO - -Not implemented. (S<Mac OS>) - -=item getpwent - -Not implemented. (S<Mac OS>, Win32, VM/ESA) - -=item getgrent - -Not implemented. (S<Mac OS>, Win32, VMS, VM/ESA) - -=item gethostent - -Not implemented. (S<Mac OS>, Win32) - -=item getnetent - -Not implemented. (S<Mac OS>, Win32, Plan9) - -=item getprotoent - -Not implemented. (S<Mac OS>, Win32, Plan9) - -=item getservent - -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 setnetent STAYOPEN - -Not implemented. (S<Mac OS>, Win32, Plan9, S<RISC OS>) - -=item setprotoent STAYOPEN - -Not implemented. (S<Mac OS>, Win32, Plan9, S<RISC OS>) - -=item setservent STAYOPEN - -Not implemented. (Plan9, Win32, S<RISC OS>) - -=item endpwent - -Not implemented. (S<Mac OS>, MPE/iX, VM/ESA, Win32) - -=item endgrent - -Not implemented. (S<Mac OS>, MPE/iX, S<RISC OS>, VM/ESA, VMS, Win32) - -=item endhostent - -Not implemented. (S<Mac OS>, Win32) - -=item endnetent - -Not implemented. (S<Mac OS>, Win32, Plan9) - -=item endprotoent - -Not implemented. (S<Mac OS>, Win32, Plan9) - -=item endservent - -Not implemented. (Plan9, Win32) - -=item getsockopt SOCKET,LEVEL,OPTNAME - -Not implemented. (S<Mac OS>, Plan9) - -=item glob EXPR - -=item glob - -Globbing built-in, but only C<*> and C<?> metacharacters are supported. -(S<Mac OS>) - -This operator is implemented via the File::Glob extension on most -platforms. See L<File::Glob> for portability information. - -=item ioctl FILEHANDLE,FUNCTION,SCALAR - -Not implemented. (VMS) - -Available only for socket handles, and it does what the ioctlsocket() call -in the Winsock API does. (Win32) - -Available only for socket handles. (S<RISC OS>) - -=item kill SIGNAL, LIST - -Not implemented, hence not useful for taint checking. (S<Mac OS>, -S<RISC OS>) - -C<kill()> doesn't have the semantics of C<raise()>, i.e. it doesn't send -a signal to the identified process like it does on Unix platforms. -Instead C<kill($sig, $pid)> terminates the process identified by $pid, -and makes it exit immediately with exit status $sig. As in Unix, if -$sig is 0 and the specified process exists, it returns true without -actually terminating it. (Win32) - -=item link OLDFILE,NEWFILE - -Not implemented. (S<Mac OS>, MPE/iX, 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) - -Hard links are implemented on Win32 (Windows NT and Windows 2000) -under NTFS only. - -=item lstat FILEHANDLE - -=item lstat EXPR - -=item lstat - -Not implemented. (VMS, S<RISC OS>) - -Return values (especially for device and inode) may be bogus. (Win32) - -=item msgctl ID,CMD,ARG - -=item msgget KEY,FLAGS - -=item msgsnd ID,MSG,FLAGS - -=item msgrcv ID,VAR,SIZE,TYPE,FLAGS - -Not implemented. (S<Mac OS>, Win32, VMS, Plan9, S<RISC OS>, VOS) - -=item open FILEHANDLE,EXPR - -=item open FILEHANDLE - -The C<|> variants are supported only if ToolServer is installed. -(S<Mac OS>) - -open to C<|-> and C<-|> are unsupported. (S<Mac OS>, Win32, S<RISC OS>) - -Opening a process does not automatically flush output handles on some -platforms. (SunOS, Solaris, HP-UX) - -=item pipe READHANDLE,WRITEHANDLE - -Not implemented. (S<Mac OS>) - -Very limited functionality. (MiNT) - -=item readlink EXPR - -=item readlink - -Not implemented. (Win32, VMS, S<RISC OS>) - -=item select RBITS,WBITS,EBITS,TIMEOUT - -Only implemented on sockets. (Win32) - -Only reliable on sockets. (S<RISC OS>) - -Note that the C<socket FILEHANDLE> form is generally portable. - -=item semctl ID,SEMNUM,CMD,ARG - -=item semget KEY,NSEMS,FLAGS - -=item semop KEY,OPSTRING - -Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS) - -=item setgrent - -Not implemented. (MPE/iX, Win32) - -=item setpgrp PID,PGRP - -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>, VOS) - -=item setpwent - -Not implemented. (MPE/iX, Win32) - -=item setsockopt SOCKET,LEVEL,OPTNAME,OPTVAL - -Not implemented. (S<Mac OS>, Plan9) - -=item shmctl ID,CMD,ARG - -=item shmget KEY,SIZE,FLAGS - -=item shmread ID,VAR,POS,SIZE - -=item shmwrite ID,STRING,POS,SIZE - -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>, VOS, VM/ESA) - -=item stat FILEHANDLE - -=item stat EXPR - -=item stat - -Platforms that do not have rdev, blksize, or blocks will return these -as '', so numeric comparison or manipulation of these fields may cause -'not numeric' warnings. - -mtime and atime are the same thing, and ctime is creation time instead of -inode change time. (S<Mac OS>) - -device and inode are not meaningful. (Win32) - -device and inode are not necessarily reliable. (VMS) - -mtime, atime and ctime all return the last modification time. Device and -inode are not necessarily reliable. (S<RISC OS>) - -dev, rdev, blksize, and blocks are not available. inode is not -meaningful and will differ between stat calls on the same file. (os2) - -=item symlink OLDFILE,NEWFILE - -Not implemented. (Win32, VMS, S<RISC OS>) - -=item syscall LIST - -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 - -Only implemented if ToolServer is installed. (S<Mac OS>) - -As an optimization, may not call the command shell specified in -C<$ENV{PERL5SHELL}>. C<system(1, @args)> spawns an external -process and immediately returns its process designator, without -waiting for it to terminate. Return value may be used subsequently -in C<wait> or C<waitpid>. Failure to spawn() a subprocess is indicated -by setting $? to "255 << 8". C<$?> is set in a way compatible with -Unix (i.e. the exitstatus of the subprocess is obtained by "$? >> 8", -as described in the documentation). (Win32) - -There is no shell to process metacharacters, and the native standard is -to pass a command line terminated by "\n" "\r" or "\0" to the spawned -program. Redirection such as C<< > foo >> is performed (if at all) by -the run time library of the spawned program. C<system> I<list> will call -the Unix emulation library's C<exec> emulation, which attempts to provide -emulation of the stdin, stdout, stderr in force in the parent, providing -the child program uses a compatible version of the emulation library. -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 -("<" or ">") on its own behalf. (MiNT) - -Does not automatically flush output handles on some platforms. -(SunOS, Solaris, HP-UX) - -=item times - -Only the first entry returned is nonzero. (S<Mac OS>) - -"cumulative" times will be bogus. On anything other than Windows NT -or Windows 2000, "system" time will be bogus, and "user" time is -actually the time returned by the clock() function in the C runtime -library. (Win32) - -Not useful. (S<RISC OS>) - -=item truncate FILEHANDLE,LENGTH - -=item truncate EXPR,LENGTH - -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 set only when the file -is finally closed. (AmigaOS) - -=item utime LIST - -Only the modification time is updated. (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 -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>, VOS) - -Can only be applied to process handles returned for processes spawned -using C<system(1, ...)> or pseudo processes created with C<fork()>. (Win32) - -Not useful. (S<RISC OS>) - -=back - -=head1 CHANGES - -=over 4 - -=item v1.48, 02 February 2001 - -Various updates from perl5-porters over the past year, supported -platforms update from Jarkko Hietaniemi. - -=item v1.47, 22 March 2000 - -Various cleanups from Tom Christiansen, including migration of -long platform listings from L<perl>. - -=item v1.46, 12 February 2000 - -Updates for VOS and MPE/iX. (Peter Prymmer) Other small changes. - -=item v1.45, 20 December 1999 - -Small changes from 5.005_63 distribution, more changes to EBCDIC info. - -=item v1.44, 19 July 1999 - -A bunch of updates from Peter Prymmer for C<$^O> values, -endianness, File::Spec, VMS, BS2000, OS/400. - -=item v1.43, 24 May 1999 - -Added a lot of cleaning up from Tom Christiansen. - -=item v1.42, 22 May 1999 - -Added notes about tests, sprintf/printf, and epoch offsets. - -=item v1.41, 19 May 1999 - -Lots more little changes to formatting and content. - -Added a bunch of C<$^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 v1.23, 10 July 1998 - -First public release with perl5.005. - -=back - -=head1 Supported Platforms - -As of early 2001 (the Perl release 5.6.1), the following platforms are -able to build Perl from the standard source code distribution -available at http://www.perl.com/CPAN/src/index.html - - AIX - AmigaOS - Darwin (Rhapsody) - DG/UX - DOS DJGPP 1) - DYNIX/ptx - EPOC - FreeBSD - HP-UX - IRIX - Linux - MachTen - MacOS Classic 2) - NonStop-UX - ReliantUNIX (SINIX) - OpenBSD - OpenVMS (VMS) - OS/2 - OS X - QNX - Solaris - Tru64 UNIX (DEC OSF/1, Digital UNIX) - UNICOS - UNICOS/mk - VOS - Win32/NT/2K 3) - - 1) in DOS mode either the DOS or OS/2 ports can be used - 2) Mac OS Classic (pre-X) is almost 5.6.1-ready; building from - the source does work with 5.6.1, but additional MacOS specific - source code is needed for a complete build. Contact the mailing - list macperl-porters@macperl.org for more information. - 3) compilers: Borland, Cygwin, Mingw32 EGCS/GCC, VC++ - -The following platforms worked for the previous release (5.6.0), -but we did not manage to test these in time for the 5.6.1 release. -There is a very good chance that these will work fine with 5.6.1. - - DomainOS - Hurd - LynxOS - MinGW - MPE/iX - NetBSD - PowerMAX - SCO SV - SunOS - SVR4 - Unixware - Windows 3.1 - Windows 95 - Windows 98 - Windows Me - -The following platform worked for the 5.005_03 major release but not -5.6.0. Standardization on UTF-8 as the internal string representation -in 5.6.0 and 5.6.1 has introduced incompatibilities in this EBCDIC -platform. While Perl 5.6.1 will build on this platform some -regression tests may fail and the C<use utf8;> pragma typically -introduces text handling errors. UTF-8 support for this platform may -be enabled in a future release: - - OS/390 1) - - 1) previously known as MVS, about to become z/OS. - -Strongly related to the OS/390 platform by also being EBCDIC-based -mainframe platforms are the following platforms: - - POSIX-BC (BS2000) - VM/ESA - -These are also expected to work, albeit with no UTF-8 support, under 5.6.1 -for the same reasons as OS/390. Contact the mailing list perl-mvs@perl.org -for more details. - -The following platforms have been known to build Perl from source in -the past (5.005_03 and earlier), but we haven't been able to verify -their status for the current release, either because the -hardware/software platforms are rare or because we don't have an -active champion on these platforms--or both. They used to work, -though, so go ahead and try compiling them, and let perlbug@perl.org -of any trouble. - - 3b1 - A/UX - BeOS - BSD/OS - ConvexOS - CX/UX - DC/OSx - DDE SMES - DOS EMX - Dynix - EP/IX - ESIX - FPS - GENIX - Greenhills - ISC - MachTen 68k - MiNT - MPC - NEWS-OS - NextSTEP - OpenSTEP - Opus - Plan 9 - PowerUX - RISC/os - SCO ODT/OSR - Stellar - SVR2 - TI1500 - TitanOS - Ultrix - Unisys Dynix - Unixware - UTS - -Support for the following platform is planned for a future Perl release: - - Netware - -The following platforms have their own source code distributions and -binaries available via http://www.perl.com/CPAN/ports/index.html: - - Perl release - - Netware 5.003_07 - OS/400 5.005_02 - Tandem Guardian 5.004 - -The following platforms have only binaries available via -http://www.perl.com/CPAN/ports/index.html : - - Perl release - - Acorn RISCOS 5.005_02 - AOS 5.002 - LynxOS 5.004_02 - -Although we do suggest that you always build your own Perl from -the source code, both for maximal configurability and for security, -in case you are in a hurry you can check -http://www.perl.com/CPAN/ports/index.html for binary distributions. - -=head1 SEE ALSO - -L<perlaix>, L<perlamiga>, L<perlcygwin>, L<perldos>, L<perlepoc>, -L<perlebcdic>, L<perlhpux>, L<perlos2>, L<perlos390>, L<perlbs2000>, -L<perlwin32>, L<perlvms>, L<perlvos>, and L<Win32>. - -=head1 AUTHORS / CONTRIBUTORS - -Abigail <abigail@fnx.com>, -Charles Bailey <bailey@newman.upenn.edu>, -Graham Barr <gbarr@pobox.com>, -Tom Christiansen <tchrist@perl.com>, -Nicholas Clark <Nicholas.Clark@liverpool.ac.uk>, -Thomas Dorner <Thomas.Dorner@start.de>, -Andy Dougherty <doughera@lafcol.lafayette.edu>, -Dominic Dunlop <domo@vo.lu>, -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>, -Luther Huffman <lutherh@stratcom.com>, -Nick Ing-Simmons <nick@ni-s.u-net.com>, -Andreas J. KE<ouml>nig <koenig@kulturbox.de>, -Markus Laker <mlaker@contax.co.uk>, -Andrew M. Langmead <aml@world.std.com>, -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>, -Gary Ng <71564.1743@CompuServe.COM>, -Tom Phoenix <rootbeer@teleport.com>, -AndrE<eacute> Pirard <A.Pirard@ulg.ac.be>, -Peter Prymmer <pvhp@forte.com>, -Hugo van der Sanden <hv@crypt0.demon.co.uk>, -Gurusamy Sarathy <gsar@activestate.com>, -Paul J. Schinder <schinder@pobox.com>, -Michael G Schwern <schwern@pobox.com>, -Dan Sugalski <sugalskd@ous.edu>, -Nathan Torkington <gnat@frii.com>. - -This document is maintained by Chris Nandor -<pudge@pobox.com>. - -=head1 VERSION - -Version 1.47, last modified 22 March 2000 |
