X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=pod%2Fperlport.pod;h=3458c7c581cb2782bd6da560fdac7283cfea2024;hb=58103a2e295c15d87c7ce0bd8dd83d7e110adac4;hp=e81e146ae75193180bfab7c66621a48001fdded6;hpb=f224927c1e379a33cd6d5e0a5d25d0ecb9c9d964;p=p5sagit%2Fp5-mst-13.2.git
diff --git a/pod/perlport.pod b/pod/perlport.pod
index e81e146..3458c7c 100644
--- a/pod/perlport.pod
+++ b/pod/perlport.pod
@@ -67,15 +67,15 @@ 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
+portability (L<"ISSUES">), platform-specific issues (L<"PLATFORMS">), and
built-in perl functions that behave differently on various ports
-(L<"FUNCTION IMPLEMENTATIONS">.
+(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
-(
).
+(C<<
>>).
=head1 ISSUES
@@ -104,11 +104,11 @@ newlines:
#...
}
-You can get away with this on Unix and MacOS (they have a single
+You can get away with this on Unix and Mac OS (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().
+chomp() should be used to trim newlines. The L 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
@@ -171,8 +171,8 @@ newline representation. A single line of code will often suffice:
Some of this may be confusing. Here's a handy reference to the ASCII CR
and LF characters. You can print it out and stick it in your wallet.
- LF == \012 == \x0A == \cJ == ASCII 10
- CR == \015 == \x0D == \cM == ASCII 13
+ LF eq \012 eq \x0A eq \cJ eq chr(10) eq ASCII 10
+ CR eq \015 eq \x0D eq \cM eq chr(13) eq ASCII 13
| Unix | DOS | Mac |
---------------------------
@@ -188,7 +188,23 @@ The Unix column assumes that you are not accessing a serial line
"\n", and "\n" on output becomes CRLF.
These are just the most common definitions of C<\n> and C<\r> in Perl.
-There may well be others.
+There may well be others. For example, on an EBCDIC implementation
+such as z/OS (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
=head2 Numbers endianness and Width
@@ -208,6 +224,10 @@ them in big-endian mode. To avoid this problem in network (socket)
connections use the C and C formats C and C, the
"network" orders. These are guaranteed to be portable.
+As of perl 5.9.2, you can also use the C> and C> 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:
@@ -262,7 +282,7 @@ 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).
-The "inode change timestamp" (the <-C> filetest) may really be the
+The "inode change timestamp" (the C<-C> filetest) may really be the
"creation timestamp" (which it is not in UNIX).
VOS perl can emulate Unix filenames with C> as path separator. The
@@ -340,7 +360,8 @@ Whitespace in filenames is tolerated on most systems, but not all,
and even on systems where it might be tolerated, some utilities
might become confused by such whitespace.
-Many systems (DOS, VMS) cannot have more than one C<.> in their filenames.
+Many systems (DOS, VMS ODS-2) 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, or even
@@ -357,7 +378,7 @@ Three-arg open can also help protect against this translation in cases
where it is undesirable.
Don't use C<:> as a part of a filename since many systems use that for
-their own semantics (MacOS Classic for separating pathname components,
+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 C<@>, C<;> and
C<|>.
@@ -388,10 +409,12 @@ 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 files when you are done with them. Don't
-C or C an open file. Don't C or C a
-file already tied or opened; C or C it first.
+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 C files when you
+are done with them. Don't C or C an open file. Don't
+C or C a file already tied or opened; C or C
+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.
@@ -430,7 +453,82 @@ C instead.
Don't count on per-program environment variables, or per-program current
directories.
-Don't count on specific values of C<$!>.
+Don't count on specific values of C<$!>, neither numeric nor
+especially the strings values-- users may switch their locales causing
+error messages to be translated into their languages. If you can
+trust a POSIXish environment, you can portably use the symbols defined
+by the Errno module, like ENOENT. And don't trust on the values of C<$!>
+at all except immediately after a failed system call.
+
+=head2 Command names versus file pathnames
+
+Don't assume that the name used to invoke a command or program with
+C or C can also be used to test for the existence of the
+file that holds the executable code for that command or program.
+First, many systems have "internal" commands that are built-in to the
+shell or OS and while these commands can be invoked, there is no
+corresponding file. Second, some operating systems (e.g., Cygwin,
+DJGPP, OS/2, and VOS) have required suffixes for executable files;
+these suffixes are generally permitted on the command name but are not
+required. Thus, a command like "perl" might exist in a file named
+"perl", "perl.exe", or "perl.pm", depending on the operating system.
+The variable "_exe" in the Config module holds the executable suffix,
+if any. Third, the VMS port carefully sets up $^X and
+$Config{perlpath} so that no further processing is required. This is
+just as well, because the matching regular expression used below would
+then have to deal with a possible trailing version number in the VMS
+file name.
+
+To convert $^X to a file pathname, taking account of the requirements
+of the various operating system possibilities, say:
+
+ use Config;
+ $thisperl = $^X;
+ if ($^O ne 'VMS')
+ {$thisperl .= $Config{_exe} unless $thisperl =~ m/$Config{_exe}$/i;}
+
+To convert $Config{perlpath} to a file pathname, say:
+
+ use Config;
+ $thisperl = $Config{perlpath};
+ if ($^O ne 'VMS')
+ {$thisperl .= $Config{_exe} unless $thisperl =~ m/$Config{_exe}$/i;}
+
+=head2 Networking
+
+Don't assume that you can reach the public Internet.
+
+Don't assume that there is only one way to get through firewalls
+to the public Internet.
+
+Don't assume that you can reach outside world through any other port
+than 80, or some web proxy. ftp is blocked by many firewalls.
+
+Don't assume that you can send email by connecting to the local SMTP port.
+
+Don't assume that you can reach yourself or any node by the name
+'localhost'. The same goes for '127.0.0.1'. You will have to try both.
+
+Don't assume that the host has only one network card, or that it
+can't bind to many virtual IP addresses.
+
+Don't assume a particular network device name.
+
+Don't assume a particular set of ioctl()s will work.
+
+Don't assume that you can ping hosts and get replies.
+
+Don't assume that any particular port (service) will respond.
+
+Don't assume that Sys::Hostname (or any other API or command)
+returns either a fully qualified hostname or a non-qualified hostname:
+it all depends on how the system had been configured. Also remember
+things like DHCP and NAT-- the hostname you get back might not be very
+useful.
+
+All the above "don't":s may look daunting, and they are -- but the key
+is to degrade gracefully if one cannot reach the particular network
+service one wants. Croaking or hanging do not look very professional.
=head2 Interprocess Communication (IPC)
@@ -516,16 +614,24 @@ work with any DBM module. See L for more details.
The system's notion of time of day and calendar date is controlled in
widely different ways. Don't assume the timezone is stored in C<$ENV{TZ}>,
and even if it is, don't assume that you can control the timezone through
-that variable.
+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. 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, can be converted to an OS-specific representation using
-Time::Local.
+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 to 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 Date::Parse.
+An array of values, such as those returned by C, 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.
@@ -537,6 +643,9 @@ 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.
+On Windows (at least), you shouldn't pass a negative value to C or
+C.
+
=head2 Character sets and character encoding
Assume very little about character sets.
@@ -550,9 +659,9 @@ Do not assume that the alphabetic characters are encoded contiguously
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 comes before `b'.
+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 comes before "b".
=head2 Internationalisation
@@ -563,6 +672,25 @@ 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 L and L for more information.
+
+If you want to use non-ASCII bytes (outside the bytes 0x00..0x7f) in
+the "source code" of your code, to be portable you have to be explicit
+about what bytes they are. Someone might for example be using your
+code under a UTF-8 locale, in which case random native bytes might be
+illegal ("Malformed UTF-8 ...") This means that for example embedding
+ISO 8859-1 bytes beyond 0x7f into your strings might cause trouble
+later. If the bytes are native 8-bit bytes, you can use the C
+pragma. If the bytes are in a string (regular expression being a
+curious string), you can often also use the C<\xHH> notation instead
+of embedding the bytes as-is. If they are in some particular legacy
+encoding (ether single-byte or something more complicated), you can
+use the C pragma. (If you want to write your code in UTF-8,
+you can use either the C pragma, or the C pragma.)
+The C and C pragmata are available since Perl 5.6.0, and
+the C pragma since Perl 5.8.0.
+
=head2 System Resources
If your code is destined for systems with severely constrained (or
@@ -624,12 +752,14 @@ 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<$!> after a system call. Some platforms expect a certain
-output format, and perl on those platforms may have been adjusted
-accordingly. Most specifically, don't anchor a regex when testing
-an error value.
+assume certain things about the filesystem and paths. Be careful not
+to depend on a specific output style for errors, such as when checking
+C<$!> after a failed system call. Using C<$!> for anything else than
+displaying it as output is doubtful (though see the Errno module for
+testing reasonably portably for error value). Some platforms expect
+a certain output format, and Perl on those platforms may have been
+adjusted accordingly. Most specifically, don't anchor a regex when
+testing an error value.
=head1 CPAN Testers
@@ -643,11 +773,17 @@ problems in their code that crop up because of lack of testing on other
platforms; two, to provide users with information about whether
a given module works on a given platform.
+Also see:
+
=over 4
-=item Mailing list: cpan-testers@perl.org
+=item *
+
+Mailing list: cpan-testers@perl.org
+
+=item *
-=item Testing results: http://testers.cpan.org/
+Testing results: http://testers.cpan.org/
=back
@@ -770,10 +906,11 @@ DOSish perls are as follows:
Windows NT MSWin32 MSWin32-x86 2 4 xx
Windows NT MSWin32 MSWin32-ALPHA 2 4 xx
Windows NT MSWin32 MSWin32-ppc 2 4 xx
- Windows 2000 MSWin32 MSWin32-x86 2 5 xx
- Windows XP MSWin32 MSWin32-x86 2 ?
+ Windows 2000 MSWin32 MSWin32-x86 2 5 00
+ Windows XP MSWin32 MSWin32-x86 2 5 01
+ Windows 2003 MSWin32 MSWin32-x86 2 5 02
Windows CE MSWin32 ? 3
- Cygwin cygwin ?
+ Cygwin cygwin cygwin
The various MSWin32 Perl's can distinguish the OS they are running on
via the value of the fifth element of the list returned from
@@ -784,6 +921,13 @@ Win32::GetOSVersion(). For example:
print +('3.1','95','NT')[$os_version_info[4]],"\n";
}
+There are also Win32::IsWinNT() and Win32::IsWin95(), try C,
+and as of libwin32 0.19 (not part of the core Perl distribution)
+Win32::GetOSName(). 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
+
Also see:
=over 4
@@ -905,11 +1049,18 @@ The MacPerl Pages, http://www.macperl.com/ .
The MacPerl mailing lists, http://lists.perl.org/ .
+=item *
+
+MPW, ftp://ftp.apple.com/developer/Tool_Chest/Core_Mac_OS_Tools/
+
=back
=head2 VMS
Perl on VMS is discussed in L in the perl distribution.
+
+The official name of VMS as of this writing is OpenVMS.
+
Perl on VMS can accept either VMS- or Unix-style file
specifications as in either of the following:
@@ -946,18 +1097,79 @@ you are so inclined. For example:
Do take care with C<$ ASSIGN/nolog/user SYS$COMMAND: SYS$INPUT> if your
perl-in-DCL script expects to do things like C<< $read = ; >>.
-Filenames are in the format "name.extension;version". The maximum
-length for filenames is 39 characters, and the maximum length for
+The VMS operating system has two filesystems, known as ODS-2 and ODS-5.
+
+For ODS-2, filenames are in the format "name.extension;version". The
+maximum length for filenames is 39 characters, and the maximum length for
extensions is also 39 characters. Version is a number from 1 to
32767. Valid characters are C[A-Z0-9$_-]/>.
-VMS's RMS filesystem is case-insensitive and does not preserve case.
-C 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 with a file named F
-will return F (though that file could be opened with
+The ODS-2 filesystem is case-insensitive and does not preserve case.
+Perl simulates this by converting all filenames to lowercase internally.
+
+For ODS-5, filenames may have almost any character in them and can include
+Unicode characters. Characters that could be misinterpreted by the DCL
+shell or file parsing utilities need to be prefixed with the C<^>
+character, or replaced with hexadecimal characters prefixed with the
+C<^> character. Such prefixing is only needed with the pathnames are
+in VMS format in applications. Programs that can accept the UNIX format
+of pathnames do not need the escape characters. The maximum length for
+filenames is 255 characters. The ODS-5 file system can handle both
+a case preserved and a case sensitive mode.
+
+ODS-5 is only available on the OpenVMS for 64 bit platforms.
+
+Support for the extended file specifications is being done as optional
+settings to preserve backward compatibility with Perl scripts that
+assume the previous VMS limitations.
+
+In general routines on VMS that get a UNIX format file specification
+should return it in a UNIX format, and when they get a VMS format
+specification they should return a VMS format unless they are documented
+to do a conversion.
+
+For routines that generate return a file specification, VMS allows setting
+if the C library which Perl is built on if it will be returned in VMS
+format or in UNIX format.
+
+With the ODS-2 file system, there is not much difference in syntax of
+filenames without paths for VMS or UNIX. With the extended character
+set available with ODS-5 there can be a significant difference.
+
+Because of this, existing Perl scripts written for VMS were sometimes
+treating VMS and UNIX filenames interchangeably. Without the extended
+character set enabled, this behavior will mostly be maintained for
+backwards compatibility.
+
+When extended characters are enabled with ODS-5, the handling of
+UNIX formatted file specifications is to that of a UNIX system.
+
+VMS file specifications without extensions have a trailing dot. An
+equivalent UNIX file specification should not show the trailing dot.
+
+The result of all of this, is that for VMS, for portable scripts, you
+can not depend on Perl to present the filenames in lowercase, to be
+case sensitive, and that the filenames could be returned in either
+UNIX or VMS format.
+
+And if a routine returns a file specification, unless it is intended to
+convert it, it should return it in the same format as it found it.
+
+C by default has traditionally returned lowercased filenames.
+When the ODS-5 support is enabled, it will return the exact case of the
+filename on the disk.
+
+Files without extensions have a trailing period on them, so doing a
+C in the default mode with a file named F will
+return F when VMS is (though that file could be opened with
C).
+With support for extended file specifications and if C was
+given a UNIX format directory, a file named F will return F
+and optionally in the exact case on the disk. When C is given
+a VMS format directory, then C should return F, and
+again with the optionally the exact case.
+
RMS had an eight level limit on directory depths from any rooted logical
(allowing 16 levels overall) prior to VMS 7.2. Hence
C is a valid directory specification but
@@ -968,17 +1180,22 @@ as C.
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.
+native formats. It is also now the only way that you should check to
+see if VMS is in a case sensitive mode.
What C<\n> represents depends on the type of file opened. It usually
represents C<\012> but it could also be C<\015>, C<\012>, C<\015\012>,
-C<\000>, C<\040>, or nothing depending on the file organiztion and
+C<\000>, C<\040>, or nothing depending on the file organization and
record format. 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 TCP/IP library support for all current versions of VMS is dynamically
+loaded if present, so even if the routines are configured, they may
+return a status indicating that they are not implemented.
+
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:
@@ -989,10 +1206,16 @@ you can examine the content of the C<@INC> array like so:
} elsif (grep(/VMS_VAX/, @INC)) {
print "I'm on VAX!\n";
+ } elsif (grep(/VMS_IA64/, @INC)) {
+ print "I'm on IA64!\n";
+
} else {
print "I'm not so sure about where $^O is...\n";
}
+In general, the significant differences should only be if Perl is running
+on VMS_VAX or one of the 64 bit OpenVMS platforms.
+
On VMS, perl determines the UTC offset from the C
logical name. Although the VMS epoch began at 17-NOV-1858 00:00:00.00,
calls to C are adjusted to count offsets from
@@ -1024,12 +1247,12 @@ Perl on VOS is discussed in F in the perl distribution
(installed as L). Perl on VOS can accept either VOS- or
Unix-style file specifications as in either of the following:
- $ perl -ne "print if /perl_setup/i" >system>notices
- $ perl -ne "print if /perl_setup/i" /system/notices
+ C<< $ perl -ne "print if /perl_setup/i" >system>notices >>
+ C<< $ perl -ne "print if /perl_setup/i" /system/notices >>
or even a mixture of both as in:
- $ perl -ne "print if /perl_setup/i" >system/notices
+ C<< $ perl -ne "print if /perl_setup/i" >system/notices >>
Even though VOS allows the slash character to appear in object
names, because the VOS port of Perl interprets it as a pathname
@@ -1038,12 +1261,6 @@ 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 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:
@@ -1055,26 +1272,13 @@ can examine the content of the @INC array like so:
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
+F (installed as L)
=item *
@@ -1082,12 +1286,12 @@ 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
+Stratus mailing list. Send a letter with "subscribe Info-Stratus" in
the message body to majordomo@list.stratagy.com.
=item *
-VOS Perl on the web at http://ftp.stratus.com/pub/vos/vos.html
+VOS Perl on the web at http://ftp.stratus.com/pub/vos/posix/posix.html
=back
@@ -1100,7 +1304,9 @@ 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 for details.
+See L for details. Note that for OS/400 there is also a port of
+Perl 5.8.1/5.9.0 or later to the PASE which is ASCII-based (as opposed to
+ILE which is EBCDIC-based), see L.
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.
@@ -1171,8 +1377,6 @@ Also see:
=item *
-*
-
L, F, F, F,
L.
@@ -1182,7 +1386,7 @@ 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 *
+=item *
AS/400 Perl information at
http://as400.rochester.ibm.com/
@@ -1310,6 +1514,7 @@ in the "OTHER" category include:
OS $^O $Config{'archname'}
------------------------------------------
Amiga DOS amigaos m68k-amigos
+ BeOS beos
MPE/iX mpeix PA-RISC1.1
See also:
@@ -1342,7 +1547,7 @@ as well as from CPAN.
=item *
-Plan 9, F
+S, F
=back
@@ -1369,10 +1574,6 @@ L for a full description of available variables.
=over 8
-=item -X FILEHANDLE
-
-=item -X EXPR
-
=item -X
C<-r>, C<-w>, and C<-x> have a limited meaning only; directories
@@ -1411,13 +1612,18 @@ suffixes. C<-S> is meaningless. (Win32)
C<-x> (or C<-X>) determine if a file has an executable file type.
(S)
-=item alarm SECONDS
+=item atan2
-=item alarm
+Due to issues with various CPUs, math libraries, compilers, and standards,
+results for C may vary depending on any combination of the above.
+Perl attempts to conform to the Open Group/IEEE standards for the results
+returned from C, but cannot force the issue if the system Perl is
+run on does not allow it. (Tru64, HP-UX 10.20)
-Not implemented. (Win32)
+The current version of the standards for C is available at
+L.
-=item binmode FILEHANDLE
+=item binmode
Meaningless. (S, S)
@@ -1428,7 +1634,7 @@ filehandle may be closed, or pointer may be in a different position.
The value returned by C may be affected after the call, and
the filehandle may be flushed. (Win32)
-=item chmod LIST
+=item chmod
Only limited meaning. Disabling/enabling write permission is mapped to
locking/unlocking the file. (S)
@@ -1443,34 +1649,32 @@ Access permissions are mapped onto VOS access-control list changes. (VOS)
The actual permissions set depend on the value of the C
in the SYSTEM environment settings. (Cygwin)
-=item chown LIST
+=item chown
-Not implemented. (S, Win32, Plan9, S, VOS)
+Not implemented. (S, Win32, S, S)
Does nothing, but won't fail. (Win32)
-=item chroot FILENAME
+A little funky, because VOS's notion of ownership is a little funky (VOS).
=item chroot
-Not implemented. (S, Win32, VMS, Plan9, S, VOS, VM/ESA)
+Not implemented. (S, Win32, VMS, S, S, VOS, VM/ESA)
-=item crypt PLAINTEXT,SALT
+=item crypt
May not be available if library or source was not provided when building
perl. (Win32)
-Not implemented. (VOS)
-
-=item dbmclose HASH
+=item dbmclose
-Not implemented. (VMS, Plan9, VOS)
+Not implemented. (VMS, S, VOS)
-=item dbmopen HASH,DBNAME,MODE
+=item dbmopen
-Not implemented. (VMS, Plan9, VOS)
+Not implemented. (VMS, S, VOS)
-=item dump LABEL
+=item dump
Not useful. (S, S)
@@ -1478,7 +1682,7 @@ Not implemented. (Win32)
Invokes VMS debugger. (VMS)
-=item exec LIST
+=item exec
Not implemented. (S)
@@ -1487,8 +1691,6 @@ Implemented via Spawn. (VM/ESA)
Does not automatically flush output handles on some platforms.
(SunOS, Solaris, HP-UX)
-=item exit EXPR
-
=item exit
Emulates UNIX exit() (which considers C to indicate an error) by
@@ -1496,13 +1698,19 @@ mapping the C<1> to SS$_ABORT (C<44>). This behavior may be overridden
with the pragma C