(e.g. the FAT filesystem limits the time granularity to two seconds).
The "inode change timestamp" (the C<-C> filetest) may really be the
-"creation timestamp" (which it is not in UNIX).
+"creation timestamp" (which it is not in Unix).
VOS perl can emulate Unix filenames with C</> as path separator. The
native pathname characters greater-than, less-than, number-sign, and
separator, or go native and use C<.> for path separator and C<:> to
signal filesystems and disk names.
-Don't assume UNIX filesystem access semantics: that read, write,
+Don't assume Unix filesystem access semantics: that read, write,
and execute are all the permissions there are, and even if they 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
+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.
use File::Spec::Functions;
chdir(updir()); # go up one directory
- $file = catfile(curdir(), 'temp', 'file.txt');
+ my $file = catfile(curdir(), 'temp', 'file.txt');
# on Unix and Win32, './temp/file.txt'
# on Mac OS Classic, ':temp:file.txt'
# on VMS, '[.temp]file.txt'
better, use the three-arg version of open, unless you want the user to
be able to specify a pipe open.
- open(FILE, '<', $existing_file) or die $!;
+ open my $fh, '<', $existing_file) or die $!;
If filenames might use strange characters, it is safest to open it
with C<sysopen> instead of C<open>. C<open> is magic and can
directories.
Don't count on specific values of C<$!>, neither numeric nor
-especially the strings values-- users may switch their locales causing
+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<$!>
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;}
+ use Config;
+ my $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;}
+ use Config;
+ my $thisperl = $Config{perlpath};
+ if ($^O ne 'VMS')
+ {$thisperl .= $Config{_exe} unless $thisperl =~ m/$Config{_exe}$/i;}
=head2 Networking
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.
+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 that for
+things such as 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
+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.
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
+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
+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 Date::Parse.
it may be appropriate to calculate an offset for the epoch.
require Time::Local;
- $offset = Time::Local::timegm(0, 0, 0, 1, 0, 70);
+ my $offset = Time::Local::timegm(0, 0, 0, 1, 0, 70);
The value for C<$offset> in Unix will be C<0>, but in Mac OS Classic
will be some large number. C<$offset> can then be added to a Unix time
missing!) virtual memory systems then you want to be I<especially> mindful
of avoiding wasteful constructs such as:
- # NOTE: this is no longer "bad" in perl5.005
- for (0..10000000) {} # bad
- for (my $x = 0; $x <= 10000000; ++$x) {} # good
+ my @lines = <$very_large_file>; # bad
- @lines = <VERY_LARGE_FILE>; # bad
-
- while (<FILE>) {$file .= $_} # sometimes bad
- $file = join('', <FILE>); # better
+ while (<$fh>) {$file .= $_} # sometimes bad
+ my $file = join('', <$fh>); # better
The last two constructs may appear unintuitive to most people. The
first repeatedly grows a string, whereas the second allocates a
=head2 Security
Most multi-user platforms provide basic levels of security, usually
-implemented at the filesystem level. Some, however, do
-not-- unfortunately. Thus the notion of user id, or "home" directory,
+implemented at the filesystem level. Some, however, unfortunately do
+not. Thus the notion of user id, or "home" directory,
or even the state of being logged-in, may be unrecognizable on many
platforms. If you write programs that are security-conscious, it
is usually best to know what type of system you will be running
under so that you can write code explicitly for that platform (or
class of platforms).
-Don't assume the UNIX filesystem access semantics: the operating
+Don't assume the Unix filesystem access semantics: the operating
system or the filesystem may be using some ACL systems, which are
richer languages than the usual rwx. Even if the rwx exist,
their semantics might be different.
(From security viewpoint testing for permissions before attempting to
do something is silly anyway: if one tries this, there is potential
-for race conditions-- someone or something might change the
+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 the UNIX user and group semantics: especially, don't
+Don't assume the Unix user and group semantics: especially, don't
expect the C<< $< >> and C<< $> >> (or the C<$(> and C<$)>) to work
for switching identities (or memberships).
=item *
-Mailing list: cpan-testers@perl.org
+Mailing list: cpan-testers-discuss@perl.org
=item *
-Testing results: http://testers.cpan.org/
+Testing results: L<http://www.cpantesters.org/>
=back
be aware that each of these file specifications may have subtle
differences:
- $filespec0 = "c:/foo/bar/file.txt";
- $filespec1 = "c:\\foo\\bar\\file.txt";
- $filespec2 = 'c:\foo\bar\file.txt';
- $filespec3 = 'c:\\foo\\bar\\file.txt';
+ 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 C</> or C<\> as the path separator.
However, many command-line utilities of DOS vintage treat C</> as
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 CE MSWin32 ? 3
Cygwin cygwin cygwin
=item *
-The djgpp environment for DOS, http://www.delorie.com/djgpp/
+The djgpp environment for DOS, L<http://www.delorie.com/djgpp/>
and L<perldos>.
=item *
The EMX environment for DOS, OS/2, etc. emx@iaehv.nl,
-
ftp://hobbes.nmsu.edu/pub/os2/dev/emx/ Also L<perlos2>.
+
L<ftp://hobbes.nmsu.edu/pub/os2/dev/emx/> Also L<perlos2>.
=item *
=item *
-The ActiveState Pages, http://www.activestate.com/
+The ActiveState Pages, L<http://www.activestate.com/>
=item *
The Cygwin environment for Win32; F<README.cygwin> (installed
-as L<perlcygwin>), http://www.cygwin.com/
+as L<perlcygwin>), L<http://www.cygwin.com/>
=item *
The U/WIN environment for Win32,
-http://www.research.att.com/sw/tools/uwin/
+L<http://www.research.att.com/sw/tools/uwin/>
=item *
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
+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.
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
+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.
+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
+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
+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.
+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.
+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.
+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<open(FH, 'A')>).
With support for extended file specifications and if C<opendir> was
-given a U
NIX format directory, a file named F<A.;5> will return F<a>
+given a U
nix format directory, a file named F<A.;5> will return F<a>
and optionally in the exact case on the disk. When C<opendir> is given
a VMS format directory, then C<readdir> should return F<a.>, and
again with the optionally the exact case.
directory levels have snuck into the core by running the following in the
top-level source directory:
- $ perl -ne "$_=~s/\s+.*//; print if scalar(split /\//) > 8;" < MANIFEST
+ $ perl -ne "$_=~s/\s+.*//; print if scalar(split /\//) > 8;" < MANIFEST
The VMS::Filespec module, which gets installed as part of the build
=item *
-F<README.vms> (installed as
L<README_vms>), L<perlvms>
+F<README.vms> (installed as
F<README_vms>), L<perlvms>
=item *
=item *
-vmsperl on the web, http://www.sidhe.org/vmsperl/index.html
+vmsperl on the web, L<http://www.sidhe.org/vmsperl/index.html>
=back
=head2 VOS
-Perl on VOS is discussed in F<README.vos> in the perl distribution
-(installed as L<perlvos>). Perl on VOS can accept either VOS- or
-Unix-style file specifications as in either of the following:
+Perl on VOS (also known as OpenVOS) is discussed in F<README.vos>
+in the perl distribution (installed as L<perlvos>). Perl on VOS
+can accept either VOS- or Unix-style file specifications as in
+either of the following:
$ perl -ne "print if /perl_setup/i" >system>notices
$ perl -ne "print if /perl_setup/i" /system/notices
Even though VOS allows the slash character to appear in object
names, because the VOS port of Perl interprets it as a pathname
-delimiting character, VOS files, directories, or links whose names
-contain a slash character cannot be processed. Such files must be
-renamed before they can be processed by Perl. Note that VOS limits
-file names to 32 or fewer characters, file names cannot start with a
-C<-> character, or contain any character matching C<< tr/ !%&'()*+;<>?// >>
-
-The value of C<$^O> on VOS is "VOS". To determine the architecture that
-you are running on without resorting to loading all of C<%Config> you
-can examine the content of the @INC array like so:
+delimiting character, VOS files, directories, or links whose
+names contain a slash character cannot be processed. Such files
+must be renamed before they can be processed by Perl.
+
+Older releases of VOS (prior to OpenVOS Release 17.0) limit file
+names to 32 or fewer characters, prohibit file names from
+starting with a C<-> character, and prohibit file names from
+containing any character matching C<< tr/ !#%&'()*;<=>?// >>.
+
+Newer releases of VOS (OpenVOS Release 17.0 or later) support a
+feature known as extended names. On these releases, file names
+can contain up to 255 characters, are prohibited from starting
+with a C<-> character, and the set of prohibited characters is
+reduced to any character matching C<< tr/#%*<>?// >>. There are
+restrictions involving spaces and apostrophes: these characters
+must not begin or end a name, nor can they immediately precede or
+follow a period. Additionally, a space must not immediately
+precede another space or hyphen. Specifically, the following
+character combinations are prohibited: space-space,
+space-hyphen, period-space, space-period, period-apostrophe,
+apostrophe-period, leading or trailing space, and leading or
+trailing apostrophe. Although an extended file name is limited
+to 255 characters, a path name is still limited to 256
+characters.
+
+The value of C<$^O> on VOS is "VOS". To determine the
+architecture that you are running on without resorting to loading
+all of C<%Config> you can examine the content of the @INC array
+like so:
if ($^O =~ /VOS/) {
print "I'm on a Stratus box!\n";
The VOS mailing list.
There is no specific mailing list for Perl on VOS. You can post
-comments to the comp.sys.stratus newsgroup, or subscribe to the general
-Stratus mailing list. Send a letter with "subscribe Info-Stratus" in
-the message body to majordomo@list.stratagy.com.
+comments to the comp.sys.stratus newsgroup, or use the contact
+information located in the distribution files on the Stratus
+Anonymous FTP site.
=item *
-VOS Perl on the web at http://ftp.stratus.com/pub/vos/posix/posix.html
+VOS Perl on the web at L<http://ftp.stratus.com/pub/vos/posix/posix.html>
=back
Some simple tricks for determining if you are running on an EBCDIC
platform could include any of the following (perhaps all):
- if ("\t" eq "\05") { print "EBCDIC may be spoken here!\n"; }
+ if ("\t" eq "\005") { print "EBCDIC may be spoken here!\n"; }
if (ord('A') == 193) { print "EBCDIC may be spoken here!\n"; }
=item *
AS/400 Perl information at
-http://as400.rochester.ibm.com/
+L<http://as400.rochester.ibm.com/>
as well as on CPAN in the F<ports/> directory.
=back
The Unix emulation library's translation of filenames to native assumes
that this sort of translation is required, and it allows a user-defined list
of known suffixes that it will transpose in this fashion. This may
-seem transparent, but consider that with these rules C<foo/bar/baz.h>
-and C<foo/bar/h/baz> both map to C<foo.bar.h.baz>, and that C<readdir> and
+seem transparent, but consider that with these rules F<foo/bar/baz.h>
+and F<foo/bar/h/baz> both map to F<foo.bar.h.baz>, and that C<readdir> and
C<glob> cannot and do not attempt to emulate the reverse mapping. Other
C<.>'s in filenames are translated to C</>.
=item *
HP 300 MPE/iX, F<README.mpeix> and Mark Bixby's web page
-http://www.bixby.org/mark/porting.html
+L<http://www.bixby.org/mark/porting.html>
=item *
A free perl5-based PERL.NLM for Novell Netware is available in
-precompiled binary and source code form from http://www.novell.com/
+precompiled binary and source code form from L<http://www.novell.com/>
as well as from CPAN.
=item *
C<-x> (or C<-X>) determine if a file has an executable file type.
(S<RISC OS>)
+=item alarm
+
+Emulated using timers that must be explicitly polled whenever Perl
+wants to dispatch "safe signals" and therefore cannot interrupt
+blocking system calls. (Win32)
+
=item atan2
Due to issues with various CPUs, math libraries, compilers, and standards,
Does not automatically flush output handles on some platforms.
(SunOS, Solaris, HP-UX)
+Not supported. (Symbian OS)
+
=item exit
-Emulates UNIX exit() (which considers C<exit 1> to indicate an error) by
+Emulates Unix exit() (which considers C<exit 1> to indicate an error) by
mapping the C<1> to SS$_ABORT (C<44>). This behavior may be overridden
with the pragma C<use vmsish 'exit'>. As with the CRTL's exit()
function, C<exit 0> is also mapped to an exit status of SS$_NORMAL
the C library _POSIX_EXIT macro so that it can be decoded by other
programs, particularly ones written in C, like the GNV package. (VMS)
+C<exit()> resets file pointers, which is a problem when called
+from a child process (created by C<fork()>) in C<BEGIN>.
+A workaround is to use C<POSIX::_exit>. (Solaris)
+
+ exit unless $Config{archname} =~ /\bsolaris\b/;
+ require POSIX and POSIX::_exit(0);
+
=item fcntl
Not implemented. (Win32)
+
Some functions available based on the version of VMS. (VMS)
=item flock
Not implemented (VMS, S<RISC OS>, VOS).
-Available only on Windows NT (not on Windows 95). (Win32)
-
=item fork
Not implemented. (AmigaOS, S<RISC OS>, VM/ESA, VMS)
it will become inaccurate as the time gets larger. This is a bug and
will be fixed in the future.
+On VOS, time values are 32-bit quantities.
+
=item ioctl FILEHANDLE,FUNCTION,SCALAR
Not implemented. (VMS)
=item link
-Not implemented. (MPE/iX, S<RISC OS>)
+Not implemented. (MPE/iX, S<RISC OS>, VOS)
Link count not updated because hard links are not quite that hard
(They are sort of half-way between hard and soft links). (AmigaOS)
=item localtime
-localtime() has the same range as L<gmtime>, but because time zone
+localtime() has the same range as L</gmtime>, but because time zone
rules change its accuracy for historical and future times may degrade
but usually by no more than an hour.
Can't move directories between directories on different logical volumes. (Win32)
+=item rewinddir
+
+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. (Win32)
+
=item select
Only implemented on sockets. (Win32, VMS)
=item semop
-Not implemented. ( Win32, VMS, S<RISC OS>, VOS)
+Not implemented. (Win32, VMS, S<RISC OS>)
=item setgrent
-Not implemented. (MPE/iX, VMS, Win32, S<RISC OS>, VOS)
+Not implemented. (MPE/iX, VMS, Win32, S<RISC OS>)
=item setpgrp
=item setpwent
-Not implemented. (MPE/iX, Win32, S<RISC OS>, VOS)
+Not implemented. (MPE/iX, Win32, S<RISC OS>)
=item setsockopt
=item sockatmark
A relatively recent addition to socket functions, may not
-be implemented even in UNIX platforms.
+be implemented even in Unix platforms.
=item socketpair
-Not implemented. (S<RISC OS>, VOS, VM/ESA)
+Not implemented. (S<RISC OS>, VM/ESA)
+
+Available on OpenVOS Release 17.0 or later. (VOS)
Available on 64 bit OpenVMS 8.2 and later. (VMS)
=back
-=head1 Supported Platforms (Perl 5.12)
-
-
-As of _____ 20??, (The release of Perl 5.12), the following platforms are
-known to build Perl from the standard source code distribution available
-at http://www.cpan.org/src
+=head1 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 L<http://www.cpan.org/src>
=over
=item FreeBSD
+=item Debian GNU/kFreeBSD
+
=item Haiku
=item Irix (6.5. What else?)
=item Dragonfly BSD
+=item QNX Neutrino RTOS (6.5.0)
+
=item MirOS BSD
Caveats:
=back
-
=item Symbian (Series 60 v3, 3.2 and 5 - what else?)
-=item Stratus VOS
+=item Stratus VOS / OpenVOS
=item AIX
=back
-=head1 EOL Platforms (Perl 5.12)
+=head1 EOL Platforms (Perl 5.14)
The following platforms were supported by a previous version of
Perl but have been officially removed from Perl's source code
=back
-The following platforms may still work as of Perl 5.12, but Perl's
-developers have made an explicit decision to discontinue support for
-them:
+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:
=over
As of July 2002 (the Perl release 5.8.0), the following platforms were
able to build Perl from the standard source code distribution
-available at http://www.cpan.org/src/
+available at L<http://www.cpan.org/src/>
AIX
BeOS
Unisys Dynix
The following platforms have their own source code distributions and
-binaries available via http://www.cpan.org/ports/
+binaries available via L<http://www.cpan.org/ports/>
Perl release
Tandem Guardian 5.004
The following platforms have only binaries available via
-http://www.cpan.org/ports/index.html :
+L<http://www.cpan.org/ports/index.html> :
Perl release
Although we do suggest that you always build your own Perl from
the source code, both for maximal configurability and for security,
in case you are in a hurry you can check
-http://www.cpan.org/ports/index.html for binary distributions.
+L<http://www.cpan.org/ports/index.html> for binary distributions.
=head1 SEE ALSO
-L<perlaix>, L<perlamiga>, L<perl
apollo>, L<perlbeos>, L<perlbs2000>,
+L<perlaix>, L<perlamiga>, L<perlbeos>, L<perlbs2000>,
L<perlce>, L<perlcygwin>, L<perldgux>, L<perldos>, L<perlepoc>,
L<perlebcdic>, L<perlfreebsd>, L<perlhurd>, L<perlhpux>, L<perlirix>,
L<perlmacos>, L<perlmacosx>, L<perlmpeix>,
Paul J. Schinder <schinder@pobox.com>,
Michael G Schwern <schwern@pobox.com>,
Dan Sugalski <dan@sidhe.org>,
-Nathan Torkington <gnat@frii.com>.
+Nathan Torkington <gnat@frii.com>,
John Malmberg <wb8tyw@qsl.net>
https://perl5.git.perl.org / perl5.git / blobdiff