PERLPORT(1perl)

🌸 PERLPORT — Writing Portable Perl 🌸

(that's the perlport page, from the *Perl Programmers Reference Guide — yes bestie, the whole vibe is "how do I write Perl that runs literally everywhere")*

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✨ NAME ✨

perlport — the sacred text on writing portable Perl 💖

📖 DESCRIPTION 📖

Okay so here's the tea: Perl runs on so many operating systems. And like, most of them share a ton in common, but they all have their own little quirks and unique features, iykyk.

This doc exists to help you figure out what actually counts as portable Perl code. That way, once you decide "yes, I'm writing portably," you know exactly where the lines are drawn and you can stay inside them. No surprises, no chaos. 🫶

Now, real talk — there's a tradeoff between going all-in on one specific type of computer versus taking advantage of a whole range of them. Obviously the more platforms you widen your range to, the more the common factors drop, and you're left with an increasingly smaller area of common ground where you can actually operate to get a particular task done. So when you start attacking a problem, it's important to think about where on that tradeoff curve you wanna be. Specifically: you gotta decide whether it matters that the task you're coding has the full generality of being portable, or whether you just wanna get the job done right now. Honestly? That's the hardest choice to make. Everything else is easy, because Perl gives you many choices no matter which way you wanna approach your problem. 💅

Looking at it from another angle: writing portable code is usually about willfully limiting your available choices. And yes, that takes discipline and sacrifice. The product of portability and convenience may be a constant. You have been warned. 😭

Be aware of two important points, bestie:

• 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. Fr fr, sometimes you just don't need it.
• Nearly all of Perl already is portable Don't be fooled into thinking it's 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. So 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. 👑

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. Slay. 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, 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 (ISSUES), platform-specific issues (PLATFORMS), and built-in Perl functions that behave differently on various ports (FUNCTION IMPLEMENTATIONS).

Heads up: 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. So treat this material as a perpetual work in progress ("<IMG SRC="yellow_sign.gif" ALT="Under Construction">"). 🚧

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🌈 ISSUES 🌈

🦋 Newlines 🦋

In most operating systems, lines in files are terminated by newlines. But like, what gets used as a newline? Totally varies from OS to OS, bestie. Unix traditionally uses "\012", one type of DOSish I/O uses "\015\012", Mac OS uses "\015", and z/OS uses "\025".

Perl uses "\n" to represent the "logical" newline, where what is logical may depend on the platform in use. In MacPerl, "\n" always means "\015". On EBCDIC platforms, "\n" could be "\025" or "\045". In DOSish perls, "\n" usually means "\012", but when accessing a file in "text" mode, perl uses the :crlf layer that translates it to (or from) "\015\012", depending on whether you're reading or writing. Unix does the same thing on ttys in canonical mode. And "\015\012" is commonly referred to as CRLF.

To trim trailing newlines from text lines use chomp. With default settings that function looks for a trailing "\n" character and thus trims in a portable way. Iconic, no notes.

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 seek and tell on a file accessed in "text" mode. Stick to seek-ing to locations you got from tell (and no others), and you are usually free to use seek and tell even in "text" mode. Using seek or tell or other file operations may be non-portable. If you use binmode on a file, however, you can usually seek and tell with arbitrary values safely. ✨

A common misconception in socket programming is that "\n eq \012" everywhere. When using protocols such as common Internet protocols, "\012" and "\015" are called for specifically, and the values of the logical "\n" and "\r" (carriage return) are not reliable.

print $socket "Hi there, client!\r\n";      # WRONG
print $socket "Hi there, client!\015\012";  # RIGHT

However, using "\015\012" (or "\cM\cJ", or "\x0D\x0A") can be tedious and unsightly, as well as confusing to those maintaining the code. So 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 $/ is "\n", but robust socket code will recognize as either "\012" or "\015\012" as end of line:

while (<$socket>) {  # NOT ADVISABLE!
    # ...
}

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 "\015"'s ("\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. So here's a handy reference to the ASCII CR and LF characters. Print it out and stick it in your wallet, bestie. 💳

LF  eq  \012  eq  \x0A  eq  \cJ  eq  chr(10)  eq  ASCII 10
CR  eq  \015  eq  \x0D  eq  \cM  eq  chr(13)  eq  ASCII 13

         | Unix | DOS  | Mac  |
    ---------------------------
    \n   |  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 "\n" and "\r" in Perl. There may well be others! For example, on an EBCDIC implementation such as z/OS (OS/390) or OS/400 (using the ILE, the PASE is ASCII-based) the above material is similar to "Unix" but the code numbers change:

LF  eq  \025  eq  \x15  eq  \cU  eq  chr(21)  eq  CP-1047 21
LF  eq  \045  eq  \x25  eq           chr(37)  eq  CP-0037 37
CR  eq  \015  eq  \x0D  eq  \cM  eq  chr(13)  eq  CP-1047 13
CR  eq  \015  eq  \x0D  eq  \cM  eq  chr(13)  eq  CP-0037 13

         | z/OS | OS/400 |
    ----------------------
    \n   |  LF  |  LF    |
    \r   |  CR  |  CR    |
    \n * |  LF  |  LF    |
    \r * |  CR  |  CR    |
    ----------------------
    * text-mode STDIO

💜 Numbers endianness and Width 💜

Different CPUs store integers and floating point numbers in different orders (called 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 an 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 pack and unpack formats n and N, the "network" orders. These are guaranteed to be portable. 👑

As of Perl 5.10.0, you can also use the >`` and <` modifiers to force big- or little-endian byte-order. This is useful if you want to store signed integers or 64-bit integers, for example.

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 and Storable (included as of Perl 5.8). Keeping all data as text significantly simplifies matters. ✨

📂 Files and Filesystems 📂

Okay bestie, so like, most platforms these days put files in a whole hierarchical tree vibe. So it's reasonably safe to assume every platform has some concept of a "path" to uniquely ID a file on the system. But the way that path is actually written?? Yeah, it differs considerably, no cap.

Even though they're similar, file path specs differ between Unix, Windows, Mac OS, OS/2, VMS, VOS, RISC OS, and probably a bunch of others. Unix, for example, is one of the few OSes with the elegant idea of a single root directory. Iconic behavior honestly.

DOS, OS/2, VMS, VOS, and Windows can work kinda similarly to Unix with / as path separator, OR they go full idiosyncratic on you (like having several root directories and various "unrooted" device files such as NIL: and LPT:). It's giving chaos.

Mac OS 9 and earlier used : as a path separator instead of /. Wild, right?

The filesystem may support neither hard links (link) nor symbolic links (symlink, readlink, lstat). Sad.

The filesystem may support neither access timestamp nor change timestamp (meaning that basically the only portable timestamp is the modification timestamp), or it might only do one second granularity on any timestamps (e.g. the FAT filesystem caps time granularity at two seconds). 💀

The "inode change timestamp" (the -C filetest) may really be the "creation timestamp" (which it is not in Unix). Confusing but go off I guess.

VOS perl can emulate Unix filenames with / as path separator. The native pathname characters greater-than, less-than, number-sign, and percent-sign are always accepted.

RISC OS perl can emulate Unix filenames with / as path separator, or go native and use . for path separator and : to signal filesystems and disk names. Your choice bestie.

Don't assume Unix filesystem access semantics: that read, write, and execute are all the permissions there are, and even if they do exist, that their semantics (for example what do r, w, and x mean on a directory) are the Unix ones. The various Unix/POSIX compatibility layers usually try to make interfaces like chmod work, but sometimes there simply is no good mapping. Periodt.

The File::Spec modules provide methods to manipulate path specifications and return the results in native format for each platform. This is often unnecessary as Unix-style paths are understood by Perl on every supported platform, but if you need to produce native paths for a native utility that does not understand Unix syntax, or if you are operating on paths or path components in unknown (and thus possibly native) syntax, File::Spec is your bestie. Here are two brief examples:

    use File::Spec::Functions;
    chdir(updir());        # go up one directory

    # Concatenate a path from its components
    my $file = catfile(updir(), 'temp', 'file.txt');
    # on Unix:    '../temp/file.txt'
    # on Win32:   '..\temp\file.txt'
    # on VMS:     '[-.temp]file.txt'

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. Fr fr.

This is especially noticeable in scripts like Makefiles and test suites, which often assume / as a path separator for subdirectories. Not me catching strays 😭

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). Handy!

Even when on a single platform (if you can even call Unix a single platform), remember not to count on the existence or the contents of particular system-specific files or directories, like /etc/passwd, /etc/sendmail.conf, /etc/resolv.conf, or even /tmp/. For example, /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. The way that's just good practice ✨

Don't assume a text file will end with a newline. They should, but people forget. 🙈

Do not have two files or directories of the same name with different case, like test.pl and Test.pl, as many platforms have case-insensitive (or at least case-forgiving) filenames. Also, try not to have non-word characters (except for .) in the names, and keep them to the 8.3 convention, for maximum portability, onerous a burden though this may appear. I know bestie, it's a lot. Bear with me.

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, and even on systems where it might be tolerated, some utilities might become confused by such whitespace. Rude but true.

Many systems (DOS, VMS ODS-2) cannot have more than one . in their filenames. The audacity honestly.

Don't assume > won't be the first character of a filename. Always use the three-arg version of open:

    open my $fh, '<', $existing_file) or die $!;

Two-arg open is magic and can translate characters like >, <, and \| in filenames, which is usually the wrong thing to do. sysopen and three-arg open don't have this problem. Slay.

Don't use : as a part of a filename since many systems use that for their own semantics (Mac OS Classic for separating pathname components, many networking schemes and utilities for separating the nodename and the pathname, and so on). For the same reasons, avoid @, ; and \|.

Don't assume that in pathnames you can collapse two leading slashes // into one: some networking and clustering filesystems have special semantics for that. Let the operating system sort it out. Trust the process 🫶

The portable filename characters as defined by ANSI C are

 a b c d e f g h i j k l m n o p q r s t u v w x y z
 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
 0 1 2 3 4 5 6 7 8 9
 . _ -

and - shouldn't be the first character. If you want to be hypercorrect, stay case-insensitive and within the 8.3 naming convention (all the files and directories have to be unique within one directory if their names are lowercased and truncated to eight characters before the ., if any, and to three characters after the ., if any). (And do not use .s in directory names.) Okay that's a whole mouthful but we move.

On Windows extra .s at the end of a file or directory name are ignored in most circumstances, and a directory name containing only three or more .s are treated as the current directory by some APIs. Windows being Windows I fear.

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🖥️ 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. Self care bestie 💅

Some platforms can't delete or rename files held open by the system, this limitation may also apply to changing filesystem metainformation like file permissions or owners. Remember to close files when you are done with them. Don't unlink or rename an open file. Don't tie or open a file already tied or opened; untie or close it first. Clean up after yourself periodt!

Don't open the same file more than once at a time for writing, as some operating systems put mandatory locks on such files. Not the vibe.

Don't assume that write/modify permission on a directory gives the right to add or delete files/directories in that directory. That is filesystem specific: in some filesystems you need write/modify permission also (or even just) in the file/directory itself. In some filesystems (AFS, DFS) the permission to add/delete directory entries is a completely separate permission. The way permissions are complex.

Don't assume that a single unlink completely gets rid of the file: some filesystems (most notably the ones in VMS) have versioned filesystems, and unlink removes only the most recent one (it doesn't remove all the versions because by default the native tools on those platforms remove just the most recent version, too). The portable idiom to remove all the versions of a file is

    1 while unlink "file";

This will terminate if the file is undeletable for some reason (protected, not there, and so on).

Don't count on a specific environment variable existing in %ENV. Don't count on %ENV entries being case-sensitive, or even case-preserving. Don't try to clear %ENV by saying %ENV = ();, or, if you really have to, make it conditional on "$^O ne 'VMS'" since in VMS the %ENV table is much more than a per-process key-value string table. It's giving complex.

On VMS, some entries in the %ENV hash are dynamically created when their key is used on a read if they did not previously exist. The values for $ENV{HOME}, $ENV{TERM}, $ENV{PATH}, and $ENV{USER}, are known to be dynamically generated. The specific names that are dynamically generated may vary with the version of the C library on VMS, and more may exist than are documented.

On VMS by default, changes to the %ENV hash persist after perl exits. Subsequent invocations of perl in the same process can inadvertently inherit environment settings that were meant to be temporary. Red flag behavior tbh.

Don't count on signals or %SIG for anything. Just don't.

Don't count on filename globbing. Use opendir, readdir, and closedir instead. Do it properly bestie.

Don't count on per-program environment variables, or per-program current directories.

Don't count on specific values of $!, neither numeric nor especially the string values. Users may switch their locales causing error messages to be translated into their languages. If you can trust a POSIXish environment, you can portably use the symbols defined by the Errno module, like ENOENT. And don't trust on the values of $! at all except immediately after a failed system call. Timing is everything ✨

Command names versus file pathnames 💖

Okay bestie, so here's the tea: do NOT assume the name you use to invoke a command or program with system or exec can also be used to test if the file holding the executable code exists. Why? Three reasons, periodt.

• First: many systems have "internal" commands built-in to the shell or OS. You can invoke them, but there's literally no file. 💀
• Second: some OSes (e.g., Cygwin, OS/2, and VOS) require suffixes for executable files. Those suffixes are generally allowed on the command name but not required. So perl might live in a file called perl, perl.exe, or perl.pm, depending on the OS. The $Config{_exe} variable in the Config module holds the executable suffix, if any.
• Third: the VMS port carefully sets up $^X and $Config{perlpath} so no further processing is needed. Which is great, because otherwise the matching regex below would have to deal with a possible trailing version number in the VMS file name. 🙈

To convert $^X to a file pathname, taking into account all those OS possibilities, say:

        use Config;
        my $thisperl = $^X;
        if ($^O ne 'VMS') {
            $thisperl .= $Config{_exe}
                unless $thisperl =~ m/\Q$Config{_exe}\E$/i;
        }

And to convert $Config{perlpath} to a file pathname, say:

        use Config;
        my $thisperl = $Config{perlpath};
        if ($^O ne 'VMS') {
            $thisperl .= $Config{_exe}
                unless $thisperl =~ m/\Q$Config{_exe}\E$/i;
        }

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Networking 🌐

Bestie, the network is a lawless place. Don't assume any of this:

• Don't assume you can reach the public Internet. 😭
• Don't assume there's only one way to get through firewalls to the public Internet.
• Don't assume you can reach the outside world through any port other than 80, or some web proxy. ftp is blocked by many firewalls.
• Don't assume you can send email by connecting to the local SMTP port.
• Don't assume you can reach yourself or any node by the name 'localhost'. Same goes for '127.0.0.1'. You'll have to try both.
• Don't assume the host has only one network card, or that it can't bind to many virtual IP addresses.
• Don't assume a particular network device name.
• Don't assume a particular set of "ioctl"s will work.
• Don't assume you can ping hosts and get replies.
• Don't assume any particular port (service) will respond.
• Don't assume that Sys::Hostname (or any other API or command) returns either a fully qualified hostname or a non-qualified hostname: it all depends on how the system was configured. Also remember that for things like DHCP and NAT, the hostname you get back might not be very useful.

All those don'ts may look daunting — and they are — but the key is to degrade gracefully if you can't reach the particular network service you want. Croaking or hanging does not look very professional. 💅

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Interprocess Communication (IPC) 🫶

Okay so generally: don't directly access the system in code meant to be portable. That means no system, exec, fork, pipe, backticks, or qx//, open with a "|", 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 don't 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. So you should seldom depend on them to produce consistent results. (Then again, if you're calling 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 sendmail:

    open(my $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 you need a portable solution, 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 (msg*(), sem*(), shm*()) is not available even on all Unix platforms. 💔

Do not use either the bare result of pack("N", 10, 20, 30, 40) or bare v-strings (such as v10.20.30.40) to represent IPv4 addresses: both forms just pack the four bytes into network order. That this would be equal to the C language in_addr struct (which is what the socket code internally uses) is not guaranteed. To be portable use the routines of the Socket module, such as inet_aton, inet_ntoa, and sockaddr_in. 🔥

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 exposes a common interface). Periodt. 👑

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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's 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. 💜

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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 NDBM_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 AnyDBM_File for more details. 🦋

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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 $ENV{TZ}, and even if it is, don't assume that you can control the timezone through that variable. Don't assume anything about the three-letter timezone abbreviations (for example that MST would be the Mountain Standard Time, it's been known to stand for Moscow Standard Time). If you need to use timezones, express them in some unambiguous format like the exact number of minutes offset from UTC, or the POSIX timezone format. 🕰️

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, or YYYY-MM-DDTHH:MM:SS (that's a literal "T" separating the date from the time). Please do use the ISO 8601 instead of making us guess what date 02/03/04 might be. ISO 8601 even sorts nicely as-is. A text representation (like "1987-12-18") can be easily converted into an OS-specific value using a module like Time::Piece (see "Date Parsing" in Time::Piece) or Date::Parse. An array of values, such as those returned by 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. Like:

        use Time::Local qw(timegm);
        my $offset = timegm(0, 0, 0, 1, 0, 1970);

The value for $offset in Unix will be 0, but in Mac OS Classic will be some large number. $offset can then be added to a Unix time value to get what should be the proper value on any system. 💖

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Character sets and character encoding 🔤

Assume very little about character sets. 🙈

Assume nothing about numerical values (ord, chr) of characters. Do not use explicit code point ranges (like \xHH-\xHH)). However, starting in Perl v5.22, regular expression pattern bracketed character class ranges specified like qr/[\N{U+HH}-\N{U+HH}]/ are portable, and starting in Perl v5.24, the same ranges are portable in tr///. You can portably use symbolic character classes like [:print:]. ✨

Do not assume that the alphabetic characters are encoded contiguously (in the numeric sense). There may be gaps. Special coding in Perl, however, guarantees that all subsets of qr/[A-Z]/, qr/[a-z]/, and qr/[0-9]/ behave as expected. tr/// behaves the same for these ranges. In patterns, any ranges specified with end points using the \N{...} notations ensures character set portability, but it is a bug in Perl v5.22 that this isn't true of tr///, fixed in v5.24. 💀

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 ä comes before "b". Unicode::Collate can be used to sort this all out. 🦋

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Internationalisation 🌍

If you may assume POSIX (a rather large assumption), you may read more about the POSIX locale system from 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. 💅

If you really want to be international, you should consider Unicode. See perluniintro and perlunicode for more information. 🌈

By default Perl assumes your source code is written in an 8-bit ASCII superset. To embed Unicode characters in your strings and regexes, you can use the \x{HH} or (more portably) \N{U+HH} notations. You can also use the utf8 pragma and write your code in UTF-8, which lets you use Unicode characters directly (not just in quoted constructs but also in identifiers). 👑

System Resources 💾

okay so if your code is gonna run on systems where virtual memory is severely constrained (or like, straight up missing?? bestie) then you really wanna be mindful and dodge wasteful constructs like these:

my @lines = <$very_large_file>;            # bad

while (<$fh>) {$file .= $_}                # sometimes bad
my $file = join('', <$fh>);                # better

the last two might look kinda unintuitive to most people, ngl. the first one keeps growing a string over and over, while the second one allocates one big chunk of memory all at once. on some systems, that second one is genuinely more efficient than the first. iykyk 🫶

---

Security 🔒

most multi-user platforms give you basic levels of security, usually implemented at the filesystem level. some of them, unfortunately, do not. so the whole notion of a user id, or a "home" directory, or even just being logged in may be totally unrecognizable on a bunch of platforms. if you're writing security-conscious programs, it's usually best to know what type of system you'll be running under so you can write code explicitly for that platform (or that class of platforms). periodt.

don't assume Unix filesystem access semantics, bestie. the operating system or the filesystem might be using some ACL systems, and those are richer languages than the usual "rwx". even if the "rwx" are there, their semantics might be different. it's giving... not the same vibe at all.

(from the security viewpoint, testing for permissions before attempting to do something is silly anyway: if you try that, there's potential for race conditions. someone or something might change the permissions between the permissions check and the actual operation. just try the operation. 💅)

don't assume Unix user and group semantics: especially, don't expect $< and $> (or $( and $)) to work for switching identities (or memberships). they just might not, no cap.

don't assume set-uid and set-gid semantics. (and even if you do, think twice: set-uid and set-gid are a known can of security worms. 🐛💀)

---

Style ✨

for those times when you absolutely need platform-specific code, consider keeping all of it in one place — it makes porting to other platforms way easier. use the Config module and the special variable $^O to differentiate platforms, as described in "PLATFORMS".

beware of the "else syndrome" 🙈:

if ($^O eq 'MSWin32') {
  # code that assumes Windows
} else {
  # code that assumes Linux
}

the "else" branch should be for the really ultimate fallback, not for code specific to some random platform. that's the whole point, bestie.

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, like when you're checking $! after a failed system call. using $! for anything other than displaying it as output is doubtful (though see the "Errno" module for testing reasonably portably for error value). 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. 👑

---

🌈 CPAN Testers 🌈

modules uploaded to CPAN get tested by a whole variety of volunteers on different platforms. these CPAN testers get notified by mail about every new upload, and they 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, bestie:

1. to help developers fix any problems in their code that crop up because of lack of testing on other platforms
2. to provide users with information about whether a given module works on a given platform

also see:

• Mailing list: cpan-testers-discuss@perl.org
• Testing results: https://www.cpantesters.org/

---

👑 PLATFORMS 👑

Perl is built with a $^O variable that tells you which operating system it was built on. this was implemented to help speed up code that would otherwise have to use Config and use the value of $Config{osname}. of course, to get more detailed info about the system, looking into %Config is definitely recommended. 💯

%Config cannot always be trusted though, because it was built at compile time. if perl was built in one place and then transferred somewhere else, some values may be wrong. the values may even have been edited after the fact. so like... vibe check the whole situation.

🐧 Unix

Perl works on a bewildering variety of Unix and Unix-like platforms (see e.g. most of the files in the hints/ directory in the source code kit). on most of these systems, the value of $^O (hence $Config{osname}, too) is determined either by lowercasing and stripping punctuation from the first field of the string returned by typing 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
Darwin        darwin     darwin
DYNIX/ptx     dynixptx   i386-dynixptx
FreeBSD       freebsd    freebsd-i386
Haiku         haiku      BePC-haiku
Linux         linux      arm-linux
Linux         linux      armv5tel-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      darwin     darwin
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 $Config{archname} may depend on the hardware architecture, it can vary a lot more than the value of $^O. fr fr.

🪟 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 COMMAND.COM or CMD.EXE style shells should be aware that each of these file specifications may have subtle differences:

my $filespec0 = "c:/foo/bar/file.txt";
my $filespec1 = "c:\\foo\\bar\\file.txt";
my $filespec2 = 'c:\foo\bar\file.txt';
my $filespec3 = 'c:\\foo\\bar\\file.txt';

system calls accept either "/" or "\" as the path separator. however, a lot of command-line utilities of DOS vintage treat "/" as the option prefix, so they may get confused by filenames containing "/". aside from calling any external programs, "/" will work just fine — and probably better, actually — since it's more consistent with popular usage and avoids the whole "what do i backwhack and what do i not backwhack" problem. 😭

the DOS FAT filesystem can only accommodate "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 "readdir" or used with functions like "open" or "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's best to avoid such filenames entirely 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 pl2bat.bat to put wrappers around your scripts.

newline ("\n") is translated as "\015\012" by the I/O system when reading from and writing to files (see "Newlines"). binmode($filehandle) will keep "\n" translated as "\012" for that filehandle. "binmode" should always be used for 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 $^O variable and the $Config{archname} values for various DOSish perls are as follows:

OS             $^O       $Config{archname}  ID    Version
---------------------------------------------------------
MS-DOS         dos       ?
PC-DOS         dos       ?
OS/2           os2       ?
Windows 3.1    ?         ?                  0     3 01
Windows 95     MSWin32   MSWin32-x86        1     4 00
Windows 98     MSWin32   MSWin32-x86        1     4 10
Windows ME     MSWin32   MSWin32-x86        1     ?
Windows NT     MSWin32   MSWin32-x86        2     4 xx
Windows NT     MSWin32   MSWin32-ALPHA      2     4 xx
Windows NT     MSWin32   MSWin32-ppc        2     4 xx
Windows 2000   MSWin32   MSWin32-x86        2     5 00
Windows XP     MSWin32   MSWin32-x86        2     5 01
Windows 2003   MSWin32   MSWin32-x86        2     5 02
Windows Vista  MSWin32   MSWin32-x86        2     6 00
Windows 7      MSWin32   MSWin32-x86        2     6 01
Windows 7      MSWin32   MSWin32-x64        2     6 01
Windows 2008   MSWin32   MSWin32-x86        2     6 01
Windows 2008   MSWin32   MSWin32-x64        2     6 01
Windows CE     MSWin32   ?                  3
Cygwin         cygwin    cygwin

the various MSWin32 Perl's can distinguish the OS they're 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";
}

there are also Win32::IsWinNT()|Win32/Win32::IsWinNT(), Win32::IsWin95()|Win32/Win32::IsWin95(), and Win32::GetOSName(); try perldoc Win32. the very portable POSIX::uname() will work too:

c:\> perl -MPOSIX -we "print join '|', uname"
Windows NT|moonru|5.0|Build 2195 (Service Pack 2)|x86

errors set by Winsock functions are now put directly into $^E, and the relevant "WSAE*" error codes are now exported from the Errno and POSIX modules for testing this against. slay. 🔥

okay so the OLD way of doing things — shoving those errors (converted to POSIX-style E* error codes since Perl 5.20.0) straight into $! — was buggy, and it's not even a personal-opinion thing bestie, it's literally due to the non-equivalence of like-named Winsock and POSIX error constants. And a relationship between those two has unfortunately been established in one way or another since Perl 5.8.0. 💀 iconic in the worst way.

The NEW behavior? So much more robust, no cap. It gives you an actual working solution for checking Winsock errors in portable software without accidentally matching POSIX tests that were intended for other OSes and may have totally different meanings for Winsock. vibes: fixed. ✨

The old behavior is currently retained, warts and all, for backwards compatibility — but you're encouraged to change any code that tests $! against E* constants for Winsock errors, and instead test $^E against WSAE* constants. After a suitable deprecation period, which started with Perl 5.24, the old behavior may be removed — leaving $! unchanged after Winsock function calls, to avoid any possible confusion over which error variable to check. 🫶

Also see (iykyk):

• The EMX environment for DOS, OS/2, etc. emx@iaehv.nl, <ftp://hobbes.nmsu.edu/pub/os2/dev/emx/> Also perlos2.
• Build instructions for Win32 in perlwin32, or under the Cygnus environment in perlcygwin.
• The "Win32::*" modules in Win32.
• The ActiveState Pages, <https://www.activestate.com/>
• The Cygwin environment for Win32; README.cygwin (installed as perlcygwin), <https://www.cygwin.com/>
• Build instructions for OS/2, perlos2

---

VMS 🦋

Perl on VMS is discussed in perlvms in the Perl distribution. 🌸

The official name of VMS as of this writing is OpenVMS. The more you know.

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 .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 "$ ASSIGN/nolog/user SYS$COMMAND: SYS$INPUT" if your Perl-in-DCL script expects to do things like "$read = <STDIN>;". 🙈

The VMS operating system has two filesystems, designated by their on-disk structure (ODS) level: ODS-2 and its successor ODS-5. The initial port of Perl to VMS pre-dates ODS-5, but all current testing and development assumes ODS-5 and its capabilities — including case preservation, extended characters in filespecs, and names up to 8192 bytes long. 💅

Perl on VMS can accept either VMS- or Unix-style file specifications, like 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, like in this:

$ perl -ne "print if /perl_setup/i" sys$login:/login.com
Can't open sys$login:/login.com: file specification syntax error

In general, the easiest path to portability is always to specify filenames in Unix format — unless they're gonna need to be processed by native commands or utilities. Because of that latter consideration, the File::Spec module by default returns native format specifications regardless of input format. That default may be reversed so filenames are always reported in Unix format by specifying the "DECC$FILENAME_UNIX_REPORT" feature logical in the environment. ✨

The file type, or extension, is always present in a VMS-format file specification, even if it's zero-length. Which means by default "readdir" will return a trailing dot on a file with no extension — so where you'd see "a" on Unix, you'll see "a." on VMS. That said, the trailing dot may be suppressed by enabling the "DECC$READDIR_DROPDOTNOTYPE" feature in the environment (peep the CRTL documentation on feature logical names). 🎀

What "\n" represents depends on the type of file opened. It usually represents "\012", but it could also be "\015", "\012", "\015\012", "\000", "\040", or nothing — depending on the file organization and record format. The "VMS::Stdio" module gives you access to the special fopen() requirements of files with unusual attributes on VMS.

The value of $^O on OpenVMS is "VMS". To determine the architecture you're running on, refer to $Config{archname}.

On VMS, perl determines the UTC offset from the "SYS$TIMEZONE_DIFFERENTIAL" logical name. And even though the VMS epoch began at 17-NOV-1858 00:00:00.00, calls to "localtime" are adjusted to count offsets from 01-JAN-1970 00:00:00.00, just like Unix. 👑

Also see:

• README.vms (installed as README_vms), perlvms
• vmsperl list, vmsperl-subscribe@perl.org
• vmsperl on the web, <http://www.sidhe.org/vmsperl/index.html>
• VMS Software Inc. web site, <http://www.vmssoftware.com>

---

VOS 🌈

Perl on VOS (also known as OpenVOS) is discussed in README.vos in the Perl distribution (installed as perlvos). Perl on VOS can accept either VOS- or Unix-style file specifications, like 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, like in this:

$ 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.

Older releases of VOS (prior to OpenVOS Release 17.0) limit file names to 32 or fewer characters, prohibit file names from starting with a "-" character, and prohibit file names from containing " " (space) or any character from the set "!#%&'()*;<=>?".

Newer releases of VOS (OpenVOS Release 17.0 or later) support a feature known as extended names. On these releases, file names can contain up to 255 characters, are prohibited from starting with a "-" character, and the set of prohibited characters is reduced to "#%*<>?". There are restrictions involving spaces and apostrophes: these characters must not begin or end a name, nor can they immediately precede or follow a period. Additionally, a space must not immediately precede another space or hyphen. Specifically, the following character combinations are prohibited: space-space, space-hyphen, period-space, space-period, period-apostrophe, apostrophe-period, leading or trailing space, and leading or trailing apostrophe. And even though an extended file name is limited to 255 characters, a path name is still limited to 256 characters. 💅

The value of $^O on VOS is "vos". To determine the architecture you're running on, refer to $Config{archname}.

Also see:

• README.vos (installed as perlvos)
• The VOS mailing list.

There is no specific mailing list for Perl on VOS. You can contact the Stratus Technologies Customer Assistance Center (CAC) for your region, or you can use the contact information located in the distribution files on the Stratus Anonymous FTP site.

• Stratus Technologies on the web at <http://www.stratus.com>
• VOS Open-Source Software on the web at <http://ftp.stratus.com/pub/vos/vos.html>

---

EBCDIC Platforms ✨

v5.22 core Perl runs on z/OS (formerly OS/390). Theoretically it could run on the successors of OS/400 on AS/400 minicomputers as well as 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).

The rest of this section may need updating, but we don't know what it should say. 😭 Please submit comments to <https://github.com/Perl/perl5/issues>.

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 perlos390 for details. Note that for OS/400 there is also a port of Perl 5.8.1/5.10.0 or later to the PASE, which is ASCII-based (as opposed to ILE, which is EBCDIC-based). See perlos400. 🫶

As of R2.5 of USS for OS/390 and Version 2.3 of VM/ESA these Unix sub-systems do not support the "#!" 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 "#!" shebang trick in release 2.8 and beyond. Calls to "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 hello.pl in the root of the QOpenSys file system. On the AS/400 calls to "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 "chr", "pack", "print", "printf", "ord", "sort", "sprintf", "unpack"), as well as bit-fiddling with ASCII constants using operators like "^", "&" and "|", not to mention dealing with socket interfaces to ASCII computers (see "Newlines"). 🙈

Fortunately, most web servers for the mainframe will correctly translate the "\n" in the following statement to its ASCII equivalent ("\r" is the same under both Unix and z/OS):

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

The values of $^O on some of these platforms include:

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

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

if ("\t" eq "\005")  { 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:

• perlos390, perlos400, perlbs2000, perlebcdic.
• 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.
• AS/400 Perl info lives at <http://as400.rochester.ibm.com/> and also on CPAN in the ports/ directory.

---

🌸 Acorn RISC OS 🌸

okay so Acorns use ASCII, and newlines happen as "\n", which in text files reads as "\012" — literally like Unix bestie 😌. And because Unix filename emulation is turned ON by default, most simple scripts will probably just work "out of the box". slay.

The native filesystem is modular, and individual filesystems are totally free to be case-sensitive or case-insensitive, and they're usually case-preserving. Some native filesystems have name length limits, and file and directory names get silently truncated to fit — no warning, no nothing, just vibes and shrinkage 😭. Scripts should be aware that the standard filesystem currently has a name length limit of 10 characters, with up to 77 items in a directory, but other filesystems may not impose such limitations. so like, ymmv iykyk.

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]+|

(yeah DsicName is spelled like that in the original, we are NOT fixing it, it's iconic 💅)

The default filename translation is roughly tr|/.|./|, swapping dots and slashes. simple as that.

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

Logical paths specified by system variables containing comma-separated search lists are also allowed; hence System:Modules is a valid filename, and the filesystem will prefix Modules with each section of System$Path until a name is made that points to an object on disk. Writing to a new file System:Modules would be allowed only if System$Path contains a single item list. The filesystem will also expand system variables in filenames if enclosed in angle brackets, so <System$Dir>.Modules would look for the file $ENV{'System$Dir'} . 'Modules'. The obvious implication of this is that fully qualified filenames can start with <> and the three-argument form of open should always be used. no cap, always. 🚨

Because "." 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 .h .s and .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 foo/bar/baz.h and foo/bar/h/baz both map to foo.bar.h.baz, and that readdir and glob cannot and do not attempt to emulate the reverse mapping. Other "."'s in filenames are translated to "/". so it's giving chaotic 🤡.

As implied above, the environment accessed through %ENV is global, and the convention is that program specific environment variables are of the form Program$Name. Each filesystem maintains a current directory, and the current filesystem's current directory is the 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). it's giving shared apartment energy 🏠.

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 STDIN, STDOUT, or STDERR to your children. they're just not gonna be the same handles bestie 💀.

The desire of users to express filenames of the form <Foo$Dir>.Bar on the command line unquoted causes problems, too: `` command output capture has to perform a guessing game. It assumes that a string <[^<>]+\$[^<>]> is a reference to an environment variable, whereas anything else involving < or > 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. 99% right is 1% devastating 🎀.

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 cd sdbm && make all, and anything using quoting. 😭

"RISC OS" is the proper name for the operating system, but the value in $^O is riscos (because we don't like shouting). lowercase era, respect 🙏.

---

🦋 Other perls 🦋

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

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

OS            $^O        $Config{archname}
------------------------------------------
Amiga DOS     amigaos    m68k-amigos

See also:

• Amiga, README.amiga (installed as perlamiga).
• Plan 9, README.plan9

---

👑 FUNCTION IMPLEMENTATIONS 👑

Listed below are functions that are either completely unimplemented or else have been implemented differently on various platforms. Preceding 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. and yeah, we know that's a warning, but it's an honest one 💜

Be aware, moreover, that even among Unix-ish systems there are variations. literally everyone is their own little snowflake ❄️.

For many functions, you can also query %Config, exported by default from the "Config" module. For example, to check whether the platform has the "lstat" call, check $Config{d_lstat}. See Config for a full description of available variables. (yes, "Config" with a capital C, that's a different manpage bestie, go look it up 📖)

---

📜 The Alphabetical Listing of Perl Functions (yes alphabetically, we're organized like that) 📜

• -X
  • (Win32) "-w" only inspects the read-only file attribute (FILE_ATTRIBUTE_READONLY), which determines whether the directory can be deleted, not whether it can be written to. Directories always have read and write access unless denied by discretionary access control lists (DACLs). so like, delete ≠ write, keep that straight 🧠
  • (VMS) "-r", "-w", "-x", and "-o" tell whether the file is accessible, which may not reflect UIC-based file protections.
  • (RISC OS) "-s" by name on an open file will return the space reserved on disk, rather than the current extent. "-s" on an open filehandle returns the current size. cute little split personality 💅
  • (Win32, VMS, RISC OS) "-R", "-W", "-X", "-O" are indistinguishable from "-r", "-w", "-x", "-o".
  • (Win32, VMS, RISC OS) "-g", "-k", "-u", "-A" are not particularly meaningful. 🙃
  • (VMS, RISC OS) "-l" is not particularly meaningful.
  • (Win32) "-l" returns true for both symlinks and directory junctions.
  • (VMS, RISC OS) "-p" is not particularly meaningful.
  • (VMS) "-d" is true if passed a device spec without an explicit directory.
  • (Win32) "-x" (or "-X") determine if a file ends in one of the executable suffixes.
  • (RISC OS) "-x" (or "-X") determine if a file has an executable file type.
• alarm
  • (Win32) Emulated using timers that must be explicitly polled whenever Perl wants to dispatch "safe signals" and therefore cannot interrupt blocking system calls. not me finding out my alarm can't wake me up during a blocking call 😴💀
• atan2
  • (Tru64, HP-UX 10.20) Due to issues with various CPUs, math libraries, compilers, and standards, results for "atan2" may vary depending on any combination of the above. Perl attempts to conform to the Open Group/IEEE standards for the results returned from "atan2", but cannot force the issue if the system Perl is run on does not allow it. she's trying her best 🥺
  • The current version of the standards for "atan2" is available at <http://www.opengroup.org/onlinepubs/009695399/functions/atan2.html>.
• binmode
  • (RISC OS) Meaningless. nothing to say, it's just nothing ✨
  • (VMS) Reopens file and restores pointer; if function fails, underlying filehandle may be closed, or pointer may be in a different position. risky little maneuver, be careful 🫣
  • (Win32) The value returned by "tell" may be affected after the call, and the filehandle may be flushed.
• chdir
  • (Win32) The current directory reported by the system may include any symbolic links specified to chdir().
• chmod
  • (Win32) Only good for changing "owner" read-write access; "group" and "other" bits are meaningless. group? never heard of her 💅
  • (RISC OS) Only good for changing "owner" and "other" read-write access.
  • (VOS) Access permissions are mapped onto VOS access-control list changes.
  • (Cygwin) The actual permissions set depend on the value of the "CYGWIN" variable in the SYSTEM environment settings.
  • (Android) Setting the exec bit on some locations (generally /sdcard) will return true but not actually set the bit. lying to your face, iconic behavior 😭
  • (VMS) A mode argument of zero sets permissions to the user's default permission mask rather than disabling all permissions. so 0 is NOT "lock everything", noted 📝
• chown
  • (Plan 9, RISC OS) Not implemented.
  • (Win32) Does nothing, but won't fail. fake it till you make it 🎀
  • (VOS) A little funky, because VOS's notion of ownership is a little funky. we said what we said 🕺
• chroot
  • (Win32, VMS, Plan 9, RISC OS, VOS) Not implemented.

🎀 crypt

• (Win32) Lowkey might just not be there if the library or source wasn't provided when perl was built. Rude.
• (Android) Not implemented. Periodt.

🌸 dbmclose

• (VMS, Plan 9, VOS) Not implemented.

🦋 dbmopen

• (VMS, Plan 9, VOS) Not implemented.

💅 dump

• (RISC OS) Not useful.
• (Cygwin, Win32) Not supported.
• (VMS) Invokes the VMS debugger.

✨ exec

• (Win32) exec LIST without using indirect object syntax (so, exec PROGRAM LIST) may fall back to trying the shell if the first spawn() fails.
• Heads up bestie: the list form of exec() is emulated on Win32 since the Windows API CreateProcess() accepts a simple string rather than an array of command-line arguments. This may have security implications for your code. 😭
• (SunOS, Solaris, HP-UX) Does not automatically flush output handles on some platforms.

👑 exit

• (VMS) Emulates Unix exit (which considers exit 1 to indicate an error) by mapping the 1 to SS$_ABORT (44). This behavior may be overridden with the pragma use vmsish 'exit'. As with the CRTL's exit() function, exit 0 is also mapped to an exit status of SS$_NORMAL (1); this mapping cannot be overridden. Any other argument to exit is used directly as Perl's exit status. On VMS, unless the future POSIX_EXIT mode is enabled, the exit code should always be a valid VMS exit code and not a generic number. When the POSIX_EXIT mode is enabled, a generic number will be encoded in a method compatible with the C library _POSIX_EXIT macro so that it can be decoded by other programs, particularly ones written in C, like the GNV package.
• (Solaris) exit resets file pointers, which is a problem when called from a child process (created by fork) in BEGIN. A workaround is to use POSIX::_exit.

exit unless $Config{archname} =~ /\bsolaris\b/;
require POSIX;
POSIX::_exit(0);

🌈 fcntl

• (Win32) Not implemented.
• (VMS) Some functions available based on the version of VMS.

🍓 flock

• (VMS, RISC OS, VOS) Not implemented.

🧚 fork

• (AmigaOS, RISC OS, VMS) Not implemented.
• (Win32) Emulated using multiple interpreters. See perlfork.
• (SunOS, Solaris, HP-UX) Does not automatically flush output handles on some platforms.

💜 getlogin

• (RISC OS) Not implemented.

⭐ getpgrp

• (Win32, VMS, RISC OS) Not implemented.

🫶 getppid

• (Win32, RISC OS) Not implemented.

🌸 getpriority

• (Win32, VMS, RISC OS, VOS) Not implemented.

💖 getpwnam

• (Win32) Not implemented.
• (RISC OS) Not useful.

🎀 getgrnam

• (Win32, VMS, RISC OS) Not implemented.

🦋 getnetbyname

• (Android, Win32, Plan 9) Not implemented.

✨ getpwuid

• (Win32) Not implemented.
• (RISC OS) Not useful.

💅 getgrgid

• (Win32, VMS, RISC OS) Not implemented.

👑 getnetbyaddr

• (Android, Win32, Plan 9) Not implemented.

🌈 getprotobynumber

• (Android) Not implemented.

🍓 getpwent

• (Android, Win32) Not implemented.

🧚 getgrent

• (Android, Win32, VMS) Not implemented.

💜 gethostbyname

• (Irix 5) gethostbyname('localhost') does not work everywhere: you may have to use gethostbyname('127.0.0.1').
• (Win32) If the NAME argument is an empty string ("") or something that coerces to it (such as undef), the winsock.f implementation treats this as a gethostname call and will return the standard hostname for the local computer.

⭐ gethostent

• (Win32) Not implemented.

🫶 getnetent

• (Android, Win32, Plan 9) Not implemented.

🌸 getprotoent

• (Android, Win32, Plan 9) Not implemented.

💖 getservent

• (Win32, Plan 9) Not implemented.

🎀 seekdir

• (Android) Not implemented.

🦋 sethostent

• (Android, Win32, Plan 9, RISC OS) Not implemented.

✨ setnetent

• (Win32, Plan 9, RISC OS) Not implemented.

💅 setprotoent

• (Android, Win32, Plan 9, RISC OS) Not implemented.

👑 setservent

• (Plan 9, Win32, RISC OS) Not implemented.

🌈 endpwent

• (Win32) Not implemented.
• (Android) Either not implemented or a no-op.

🍓 endgrent

• (Android, RISC OS, VMS, Win32) Not implemented.

🧚 endhostent

• (Android, Win32) Not implemented.

💜 endnetent

• (Android, Win32, Plan 9) Not implemented.

⭐ endprotoent

• (Android, Win32, Plan 9) Not implemented.

🫶 endservent

• (Plan 9, Win32) Not implemented.

🌸 getsockopt

• (Plan 9) Not implemented.

💖 glob

This operator is implemented via the File::Glob extension on most platforms. See File::Glob for portability information.

🎀 gmtime

In theory, gmtime is reliable from -263 to 263-1. However, because work-arounds in the implementation use floating point numbers, it will become inaccurate as the time gets larger. This is a bug and will be fixed in the future. 🙈

• (VOS) Time values are 32-bit quantities.

🦋 ioctl

• (VMS) Not implemented.
• (Win32) Available only for socket handles, and it does what the ioctlsocket() call in the Winsock API does.
• (RISC OS) Available only for socket handles.

✨ kill

• (RISC OS) Not implemented, hence not useful for taint checking.
• (Win32) kill doesn't send a signal to the identified process like it does on Unix platforms. Instead 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) kill(-9, $pid) will terminate the process specified by $pid and recursively all child processes owned by it. This is different from the Unix semantics, where the signal will be delivered to all processes in the same process group as the process specified by $pid.
• (VMS) A pid of -1 indicating all processes on the system is not currently supported.

💅 link

• (RISC OS, VOS) Not implemented.
• (AmigaOS) Link count not updated because hard links are not quite that hard (They are sort of half-way between hard and soft links).
• (Win32) Hard links are implemented on Win32 under NTFS only. They are natively supported on Windows 2000 and later. On Windows NT they are implemented using the Windows POSIX subsystem support and the Perl process will need Administrator or Backup Operator privileges to create hard links.
• (VMS) Available on 64 bit OpenVMS 8.2 and later.

👑 localtime

localtime has the same range as gmtime, but because time zone rules change, its accuracy for historical and future times may degrade but usually by no more than an hour.

🌈 lstat

• (RISC OS) Not implemented.
• (Win32) Treats directory junctions as symlinks.

🍓 msgctl, msgget, msgsnd, msgrcv

• (Android, Win32, VMS, Plan 9, RISC OS, VOS) Not implemented.

🧚 open

• (RISC OS) Open modes |- and -| are unsupported.
• (SunOS, Solaris, HP-UX) Opening a process does not automatically flush output handles on some platforms.
• (Win32) Both of modes |- and -| are supported, but the list form is emulated since the Win32 API CreateProcess() accepts a simple string rather than an array of arguments. This may have security implications for your code. 😭

💜 readlink

• (VMS, RISC OS) Not implemented.
• (Win32) readlink() on a directory junction returns the object name, not a simple path.

⭐ rename

• (Win32) Can't move directories between directories on different logical volumes.

🫶 rewinddir

• (Win32) Will not cause readdir to re-read the directory stream. The entries already read before the rewinddir call will just be returned again from a cache buffer.

🌸 select

• (Win32, VMS) Only implemented on sockets.
• (RISC OS) Only reliable on sockets.

Note that the select FILEHANDLE form is generally portable.

💖 semctl, semget, semop

• (Android, Win32, VMS, RISC OS) Not implemented.

🎀 setgrent

• (Android, VMS, Win32, RISC OS) Not implemented.

🦋 setpgrp

• (Win32, VMS, RISC OS, VOS) Not implemented.

✨ setpriority

• (Win32, VMS, RISC OS, VOS) Not implemented.

💅 setpwent

• (Android, Win32, RISC OS) Not implemented.

👑 setsockopt

• (Plan 9) Not implemented.

🌈 shmctl, shmget, shmread, shmwrite

• (Android, Win32, VMS, RISC OS) Not implemented.

🍓 sleep

• (Win32) Emulated using synchronization functions such that it can be interrupted by alarm, and limited to a maximum of 4294967 seconds, approximately 49 days.

🧚 socketpair

• (RISC OS) Not implemented.
• (VMS) Available on 64 bit OpenVMS 8.2 and later.

💜 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.

• (Mac OS X) ctime not supported on UFS.
• (Win32) ctime is creation time instead of inode change time.
• (VMS) dev and ino are not necessarily reliable.
• (RISC OS) mtime, atime and ctime all return the last modification time. dev and ino are not necessarily reliable.
• (OS/2) dev, rdev, blksize, and blocks are not available. ino is not meaningful and will differ between stat calls on the same file.
• (Cygwin) Some versions of cygwin when doing a stat("foo") and not finding it may then attempt to stat("foo.exe").

⭐ symlink

• (RISC OS) Not implemented.
• (Win32) Requires either elevated permissions or developer mode and a sufficiently recent version of Windows 10. You can check whether the current process has the required privileges using the Win32::IsSymlinkCreationAllowed() function.
• Since Windows needs to know whether the target is a directory or not when creating the link the target Perl will only create the link as a directory link when the target exists and is a directory.
• symlink
  • (Windows) bestie, Windows does not recognize forward slashes as path separators in symbolic links. so on Windows, any "/" in the OLDFILE parameter to symlink() gets converted to "\". and yes, that shows up in the result returned by readlink() — the "\" in the result are not converted back to "/". lowkey rude of it but okay. 💀
  • (VMS) implemented on 64 bit VMS 8.3. VMS requires the symbolic link to be in Unix syntax if it is intended to resolve to a valid path.
• syscall — (Win32, VMS, RISC OS, VOS) not implemented. that's the whole lore, no cap. 🫠
• sysopen — (Mac OS, OS/390) the traditional 0, 1, and 2 MODEs are implemented with different numeric values on some systems. the flags exported by Fcntl (O_RDONLY, O_WRONLY, O_RDWR) should work everywhere though. 🫶
• system
  • (Win32) as an optimization, it may not call the command shell specified in $ENV{PERL5SHELL}. also system(1, @args) spawns an external process and immediately returns its process designator, without waiting for it to terminate — you can hand that return value to wait or waitpid later. failure to spawn() a subprocess is indicated by setting $? to 255 << 8. $? is set in a way compatible with Unix (i.e. the exit status of the subprocess is obtained by $? >> 8, as described in the documentation). ✨

⚠️ note that the list form of system() is emulated since the Win32 API CreateProcess() accepts a simple string rather than an array of command-line arguments. this may have security implications for your code. bestie, please read that twice. 💅

• (RISC OS) 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 "> foo" is performed (if at all) by the run time library of the spawned program. system LIST will call the Unix emulation library's exec emulation, which attempts to provide emulation of the stdin, stdout, stderr in force in the parent, provided the child program uses a compatible version of the emulation library. system SCALAR will call the native command line directly and no such emulation of a child Unix program will occur. mileage will vary. 🎲
• (Win32) system LIST without the use of indirect object syntax (system PROGRAM LIST) may fall back to trying the shell if the first spawn() fails.
• (SunOS, Solaris, HP-UX) does not automatically flush output handles on some platforms. 😭
• (VMS) as with Win32, system(1, @args) spawns an external process and immediately returns its process designator without waiting for the process to terminate. in this case the return value may be used subsequently in wait or waitpid. otherwise the return value is POSIX-like (shifted up by 8 bits), which only allows room for a made-up value derived from the severity bits of the native 32-bit condition code (unless overridden by use vmsish 'status'). if the native condition code is one that has a POSIX value encoded, the POSIX value will be decoded to extract the expected exit value. for more details see "$?" in perlvms.

• telldir — (Android) not implemented. 🚫
• times
  • (Win32) "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. 🕰️
  • (RISC OS) not useful.
• truncate
  • (Older versions of VMS) not implemented.
  • (VOS) truncation to same-or-shorter lengths only.
  • (Win32) if a FILEHANDLE is supplied, it must be writable and opened in append mode (i.e., use open(my $fh, '>>', 'filename') or sysopen(my $fh, ..., O_APPEND|O_RDWR). if a filename is supplied, it should not be held open elsewhere. 😤
• umask — returns "undef" where unavailable.
  • (AmigaOS) umask works but the correct permissions are set only when the file is finally closed. patient queen energy. 👑
• utime
  • (VMS, RISC OS) only the modification time is updated.
  • (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. 🙈
• wait, waitpid
  • (Win32) can only be applied to process handles returned for processes spawned using system(1, ...) or pseudo processes created with fork.
  • (RISC OS) not useful.

---

🥳 SUPPORTED PLATFORMS 🥳

the following platforms are known to build Perl 5.12 (as of April 2010, its release date) from the standard source code distribution available at <http://www.cpan.org/src>. look at this roster, it's giving legacy. 💖

• Linux (x86, ARM, IA64)
• HP-UX
• AIX
• Win32
  • Windows 2000
  • Windows XP
  • Windows Server 2003
  • Windows Vista
  • Windows Server 2008
  • Windows 7
• Cygwin
  • some tests are known to fail:
    • ext/XS-APItest/t/call_checker.t — see <https://github.com/Perl/perl5/issues/10750>
    • dist/I18N-Collate/t/I18N-Collate.t
    • ext/Win32CORE/t/win32core.t — may fail on recent cygwin installs.
• Solaris (x86, SPARC)
• OpenVMS
  • Alpha (7.2 and later)
  • I64 (8.2 and later)
• NetBSD
• FreeBSD
• Debian GNU/kFreeBSD
• Haiku
• Irix (6.5. What else?) 🙃
• OpenBSD
• Dragonfly BSD
• Midnight BSD
• QNX Neutrino RTOS (6.5.0)
• MirOS BSD
• Stratus OpenVOS (17.0 or later)
  • Caveats:
    • time_t issues that may or may not be fixed
• Stratus VOS / OpenVOS
• AIX
• Android
• FreeMINT
  • Perl now builds with FreeMiNT/Atari. it fails a few tests, that needs some investigation. 🔍
  • the FreeMiNT port uses GNU dld for loadable module capabilities. so ensure you have that library installed when building perl.

---

👋 EOL PLATFORMS 👋

(Perl 5.37.1)

the following platforms were supported by a previous version of Perl but have been officially removed from Perl's source code as of 5.37.1:

• Ultrix

(Perl 5.36)

the following platforms were supported by a previous version of Perl but have been officially removed from Perl's source code as of 5.36:

• NetWare
• DOS/DJGPP
• AT&T UWIN

(Perl 5.20)

the following platforms were supported by a previous version of Perl but have been officially removed from Perl's source code as of 5.20:

• AT&T 3b1

(Perl 5.14)

the following platforms were supported up to 5.10. they may still have worked in 5.12, but supporting code has been removed for 5.14:

• Windows 95
• Windows 98
• Windows ME
• Windows NT4

(Perl 5.12)

the following platforms were supported by a previous version of Perl but have been officially removed from Perl's source code as of 5.12:

• Atari MiNT
• Apollo Domain/OS
• Apple Mac OS 8/9
• Tenon Machten

✨ Supported Platforms (Perl 5.8) ✨

okay so back in July 2002 (aka when Perl release 5.8.0 dropped 👑), these platforms could build Perl straight from the standard source code distribution you get at <http://www.cpan.org/src/>:

AIX
BeOS
BSD/OS          (BSDi)
Cygwin
DG/UX
DOS DJGPP       1)
DYNIX/ptx
EPOC R5
FreeBSD
HI-UXMPP        (Hitachi) (5.8.0 worked but we didn't know it)
HP-UX
IRIX
Linux
Mac OS Classic
Mac OS X        (Darwin)
MPE/iX
NetBSD
NetWare
NonStop-UX
ReliantUNIX     (formerly SINIX)
OpenBSD
OpenVMS         (formerly VMS)
Open UNIX       (Unixware) (since Perl 5.8.1/5.9.0)
OS/2
OS/400          (using the PASE) (since Perl 5.8.1/5.9.0)
POSIX-BC        (formerly BS2000)
QNX
Solaris
SunOS 4
SUPER-UX        (NEC)
Tru64 UNIX      (formerly DEC OSF/1, Digital UNIX)
UNICOS
UNICOS/mk
UTS
VOS / OpenVOS
Win95/98/ME/2K/XP 2)
WinCE
z/OS            (formerly OS/390)
VM/ESA

1) in DOS mode either the DOS or OS/2 ports can be used
2) compilers: Borland, MinGW (GCC), VC6

💅 little legend moment: those footnotes are important, don't skip 'em — 1) means in DOS mode you can use either the DOS or the OS/2 port, and 2) means the compilers are Borland, MinGW (GCC), and VC6.

---

and then there's this whole group of platforms that vibed fine with the previous releases (5.6 and 5.7), but we didn't manage to fix or test them in time for the 5.8.0 release 😭. fr fr there's a very good chance a lot of these work just fine with 5.8.0:

BSD/OS
DomainOS
Hurd
LynxOS
MachTen
PowerMAX
SCO SV
SVR4
Unixware
Windows 3.1

---

and now the 💀 section. Known to be broken for 5.8.0 (but you can still use 5.6.1 and 5.7.2 instead):

AmigaOS 3

---

the next group is giving archaeology — these platforms were 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 platform is rare, or because we don't have an active champion on it, or both. they used to work though, so go ahead and try compiling them, and let <https://github.com/Perl/perl5/issues> know of any trouble 🫶:

3b1
A/UX
ConvexOS
CX/UX
DC/OSx
DDE SMES
DOS EMX
Dynix
EP/IX
ESIX
FPS
GENIX
Greenhills
ISC
MachTen 68k
MPC
NEWS-OS
NextSTEP
OpenSTEP
Opus
Plan 9
RISC/os
SCO ODT/OSR
Stellar
SVR2
TI1500
TitanOS
Unisys Dynix

---

some platforms have their own source code distributions and binaries available via <http://www.cpan.org/ports/> 🌈

                                Perl release

OS/400 (ILE)            5.005_02
Tandem Guardian         5.004

---

and these ones have only binaries available via <http://www.cpan.org/ports/index.html> :

                                Perl release

Acorn RISCOS            5.005_02
AOS                     5.002
LynxOS                  5.004_02

ngl bestie, we do always suggest you build your own Perl from the source code — both for maximal configurability and for security 🔐. but if you're in a hurry, you can check <http://www.cpan.org/ports/index.html> for binary distributions. no judgement, we get it 💅

---

🌸 SEE ALSO 🌸

perlaix, perlamiga, perlbs2000, perlcygwin, perlebcdic, perlfreebsd, perlhurd, perlhpux, perlirix, perlmacosx, perlos2, perlos390, perlos400, perlplan9, perlqnx, perlsolaris, perltru64, perlunicode, perlvms, perlvos, perlwin32, and Win32.

---

👑 AUTHORS / CONTRIBUTORS 👑

these absolute legends, in order, periodt:

Abigail <abigail@abigail.be>, Charles Bailey <bailey@newman.upenn.edu>, Graham Barr <gbarr@pobox.com>, Tom Christiansen <tchrist@perl.com>, Nicholas Clark <nick@ccl4.org>, Thomas Dorner <Thomas.Dorner@start.de>, Andy Dougherty <doughera@lafayette.edu>, Dominic Dunlop <domo@computer.org>, Neale Ferguson <neale@vma.tabnsw.com.au>, David J. Fiander <davidf@mks.com>, Paul Green <Paul.Green@stratus.com>, M.J.T. Guy <mjtg@cam.ac.uk>, Jarkko Hietaniemi <jhi@iki.fi>, Luther Huffman <lutherh@stratcom.com>, Nick Ing-Simmons <nick@ing-simmons.net>, Andreas J. König <a.koenig@mind.de>, Markus Laker <mlaker@contax.co.uk>, Andrew M. Langmead <aml@world.std.com>, Lukas Mai <l.mai@web.de>, Larry Moore <ljmoore@freespace.net>, Paul Moore <Paul.Moore@uk.origin-it.com>, Chris Nandor <pudge@pobox.com>, Matthias Neeracher <neeracher@mac.com>, Philip Newton <pne@cpan.org>, Gary Ng <71564.1743@CompuServe.COM>, Tom Phoenix <rootbeer@teleport.com>, André 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 <dan@sidhe.org>, Nathan Torkington <gnat@frii.com>, John Malmberg <wb8tyw@qsl.net>

---

and that's the whole page bestie 😭🫶 shoutout to perl v5.44.0 for this one — the PERLPORT(1perl) page, dated 2026-10-17. that's it, that's the manual. go port something 💖✨