Unix does the same thing on ttys in canonical mode. C<\015\012>
is commonly referred to as CRLF.
+A common cause of unportable programs is the misuse of chop() to trim
+newlines:
+
+ # XXX UNPORTABLE!
+ while(<FILE>) {
+ chop;
+ @array = split(/:/);
+ #...
+ }
+
+You can get away with this on Unix and MacOS (they have a single
+character end-of-line), but the same program will break under DOSish
+perls because you're only chop()ing half the end-of-line. Instead,
+chomp() should be used to trim newlines. The Dunce::Files module can
+help audit your code for misuses of chop().
+
+When dealing with binary files (or text files in binary mode) be sure
+to explicitly set $/ to the appropriate value for your file format
+before using chomp().
+
Because of the "text" mode translation, DOSish perls have limitations
in using C<seek> and C<tell> on a file accessed in "text" mode.
Stick to C<seek>-ing to locations you got from C<tell> (and no
One can circumnavigate both these problems in two ways. Either
transfer and store numbers always in text format, instead of raw
binary, or else consider using modules like Data::Dumper (included in
-the standard distribution as of Perl 5.005) and Storable. Keeping
-all data as text significantly simplifies matters.
+the standard distribution as of Perl 5.005) and Storable (included as
+of perl 5.8). Keeping all data as text significantly simplifies matters.
=head2 Files and Filesystems
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,
+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
+layers usually try to make interfaces like chmod() work, but sometimes
+there simply is no good mapping.
+
If all this is intimidating, have no (well, maybe only a little)
fear. There are modules that can help. The File::Spec modules
provide methods to do the Right Thing on whatever platform happens
Don't open the same file more than once at a time for writing, as some
operating systems put mandatory locks on such files.
+Don't 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.
+
+Don't assume that a single C<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 undeleteable for some reason
+(protected, not there, and so on).
+
Don't count on a specific environment variable existing in C<%ENV>.
Don't count on C<%ENV> entries being case-sensitive, or even
case-preserving. Don't try to clear %ENV by saying C<%ENV = ();>, or,
The Unix System V IPC (C<msg*(), sem*(), shm*()>) is not available
even on all Unix platforms.
+Do not use either the bare result of C<pack("N", 10, 20, 30, 40)> or
+bare v-strings (such as C<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 C<in_addr> struct (which is what the
+socket code internally uses) is not guaranteed. To be portable use
+the routines of the Socket extension, such as C<inet_aton()>,
+C<inet_ntoa()>, and C<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 expose a common interface).
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,
+not-- unfortunately. Thus the notion of user id, or "home" directory,
or even the state of being logged-in, may be unrecognizable on many
platforms. If you write programs that are security-conscious, it
is usually best to know what type of system you will be running
under so that you can write code explicitly for that platform (or
class of platforms).
+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
+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
+expect the C<< $< >> and C<< $> >> (or the C<$(> and C<$)>) to work
+for switching identities (or memberships).
+
+Don't assume set-uid and set-gid semantics. (And even if you do,
+think twice: set-uid and set-gid are a known can of security worms.)
+
=head2 Style
For those times when it is necessary to have platform-specific code,
programs to aid in the testing, or when (as noted above) the tests
assume certain things about the filesystem and paths. Be careful
not to depend on a specific output style for errors, such as when
-checking C<$!> after an system call. Some platforms expect a certain
+checking C<$!> after a system call. Some platforms expect a certain
output format, and perl on those platforms may have been adjusted
accordingly. Most specifically, don't anchor a regex when testing
an error value.
Linux linux ppc-linux
HP-UX hpux PA-RISC1.1
IRIX irix irix
- Mac OS X rhapsody rhapsody
+ Mac OS X darwin darwin
MachTen PPC machten powerpc-machten
NeXT 3 next next-fat
NeXT 4 next OPENSTEP-Mach
The C<$^O> variable and the C<$Config{archname}> values for various
DOSish perls are as follows:
- OS $^O $Config{'archname'}
- --------------------------------------------
- MS-DOS dos
- PC-DOS dos
- OS/2 os2
- Windows 95 MSWin32 MSWin32-x86
- Windows 98 MSWin32 MSWin32-x86
- Windows NT MSWin32 MSWin32-x86
- Windows NT MSWin32 MSWin32-ALPHA
- Windows NT MSWin32 MSWin32-ppc
- Cygwin cygwin
+ OS $^O $Config{archname} ID Version
+ --------------------------------------------------------
+ MS-DOS dos ?
+ PC-DOS dos ?
+ OS/2 os2 ?
+ Windows 3.1 ? ? 0 3 01
+ Windows 95 MSWin32 MSWin32-x86 1 4 00
+ Windows 98 MSWin32 MSWin32-x86 1 4 10
+ Windows ME MSWin32 MSWin32-x86 1 ?
+ Windows NT MSWin32 MSWin32-x86 2 4 xx
+ Windows NT MSWin32 MSWin32-ALPHA 2 4 xx
+ Windows NT MSWin32 MSWin32-ppc 2 4 xx
+ Windows 2000 MSWin32 MSWin32-x86 2 5 xx
+ Windows XP MSWin32 MSWin32-x86 2 ?
+ Windows CE MSWin32 ? 3
+ Cygwin cygwin ?
+
+The various MSWin32 Perl's can distinguish the OS they are running on
+via the value of the fifth element of the list returned from
+Win32::GetOSVersion(). For example:
+
+ if ($^O eq 'MSWin32') {
+ my @os_version_info = Win32::GetOSVersion();
+ print +('3.1','95','NT')[$os_version_info[4]],"\n";
+ }
Also see:
=item *
The U/WIN environment for Win32,
-<http://www.research.att.com/sw/tools/uwin/
+http://www.research.att.com/sw/tools/uwin/
-=item Build instructions for OS/2, L<perlos2>
+=item *
+Build instructions for OS/2, L<perlos2>
=back
$is_ppc = $MacPerl::Architecture eq 'MacPPC';
$is_68k = $MacPerl::Architecture eq 'Mac68K';
-S<Mac OS X> and S<Mac OS X Server>, based on NeXT's OpenStep OS, will
-(in theory) be able to run MacPerl natively, under the "Classic"
-environment. The new "Cocoa" environment (formerly called the "Yellow Box")
-may run a slightly modified version of MacPerl, using the Carbon interfaces.
-
-S<Mac OS X Server> and its Open Source version, Darwin, both run Unix
-perl natively (with a few patches). Full support for these
-is slated for perl 5.6.
+S<Mac OS X>, based on NeXT's OpenStep OS, runs MacPerl natively, under the
+"Classic" environment. There is no "Carbon" version of MacPerl to run
+under the primary Mac OS X environment. S<Mac OS X> and its Open Source
+version, Darwin, both run Unix perl natively.
Also see:
=item *
-The MacPerl Pages, http://www.macperl.com/ .
+MacPerl Development, http://dev.macperl.org/ .
=item *
-The MacPerl mailing lists, http://www.macperl.org/ .
+The MacPerl Pages, http://www.macperl.com/ .
=item *
-MacPerl Module Porters, http://pudge.net/mmp/ .
+The MacPerl mailing lists, http://lists.perl.org/ .
=back
non-VMS platforms and can be helpful for conversions to and from RMS
native formats.
-What C<\n> represents depends on the type of file opened. It could
-be C<\015>, C<\012>, C<\015\012>, or nothing. The VMS::Stdio module
-provides access to the special fopen() requirements of files with unusual
-attributes on VMS.
+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
+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.
*
-L<perlos390>, F<README.os390>, F<perlposix-bc>, F<README.vmesa>,
+L<perlos390>, F<README.os390>, F<perlbs2000>, F<README.vmesa>,
L<perlebcdic>.
=item *
=item *
HP 300 MPE/iX, F<README.mpeix> and Mark Bixby's web page
-http://www.cccd.edu/~markb/perlix.html
+http://www.bixby.org/mark/perlix.html
=item *
Does not automatically flush output handles on some platforms.
(SunOS, Solaris, HP-UX)
+=item exit EXPR
+
+=item exit
+
+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
+(C<1>); this mapping cannot be overridden. Any other argument to exit()
+is used directly as Perl's exit status. (VMS)
+
=item fcntl FILEHANDLE,FUNCTION,SCALAR
Not implemented. (Win32, VMS)
=item getsockopt SOCKET,LEVEL,OPTNAME
-Not implemented. (S<Mac OS>, Plan9)
+Not implemented. (Plan9)
=item glob EXPR
=item glob
-Globbing built-in, but only C<*> and C<?> metacharacters are supported.
-(S<Mac OS>)
-
This operator is implemented via the File::Glob extension on most
platforms. See L<File::Glob> for portability information.
=item kill SIGNAL, LIST
-Not implemented, hence not useful for taint checking. (S<Mac OS>,
-S<RISC OS>)
+C<kill(0, LIST)> is implemented for the sake of taint checking;
+use with other signals is unimplemented. (S<Mac OS>)
+
+Not implemented, hence not useful for taint checking. (S<RISC OS>)
C<kill()> doesn't have the semantics of C<raise()>, i.e. it doesn't send
a signal to the identified process like it does on Unix platforms.
=item pipe READHANDLE,WRITEHANDLE
-Not implemented. (S<Mac OS>)
-
Very limited functionality. (MiNT)
=item readlink EXPR
=item select RBITS,WBITS,EBITS,TIMEOUT
-Only implemented on sockets. (Win32)
+Only implemented on sockets. (Win32, VMS)
Only reliable on sockets. (S<RISC OS>)
-Note that the C<socket FILEHANDLE> form is generally portable.
+Note that the C<select FILEHANDLE> form is generally portable.
=item semctl ID,SEMNUM,CMD,ARG
=item setsockopt SOCKET,LEVEL,OPTNAME,OPTVAL
-Not implemented. (S<Mac OS>, Plan9)
+Not implemented. (Plan9)
=item shmctl ID,CMD,ARG
Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS)
+=item sockatmark SOCKET
+
+A relatively recent addition to socket functions, may not
+be implemented even in UNIX platforms.
+
=item socketpair SOCKET1,SOCKET2,DOMAIN,TYPE,PROTOCOL
-Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS, VM/ESA)
+Not implemented. (Win32, VMS, S<RISC OS>, VOS, VM/ESA)
=item stat FILEHANDLE
dev, rdev, blksize, and blocks are not available. inode is not
meaningful and will differ between stat calls on the same file. (os2)
+some versions of cygwin when doing a stat("foo") and if not finding it
+may then attempt to stat("foo.exe") (Cygwin)
+
=item symlink OLDFILE,NEWFILE
Not implemented. (Win32, VMS, S<RISC OS>)
=item system LIST
+In general, do not assume the UNIX/POSIX semantics that you can shift
+C<$?> right by eight to get the exit value, or that C<$? & 127>
+would give you the number of the signal that terminated the program,
+or that C<$? & 128> would test true if the program was terminated by a
+coredump. Instead, use the POSIX W*() interfaces: for example, use
+WIFEXITED($?) an WEXITVALUE($?) to test for a normal exit and the exit
+value, and WIFSIGNALED($?) and WTERMSIG($?) for a signal exit and the
+signal. Core dumping is not a portable concept, so there's no portable
+way to test for that.
+
Only implemented if ToolServer is installed. (S<Mac OS>)
As an optimization, may not call the command shell specified in
Does not automatically flush output handles on some platforms.
(SunOS, Solaris, HP-UX)
+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 C<use vmsish 'status'>).
+For more details see L<perlvms/$?>. (VMS)
+
=item times
Only the first entry returned is nonzero. (S<Mac OS>)
=item truncate EXPR,LENGTH
-Not implemented. (VMS)
+Not implemented. (Older versions of VMS)
Truncation to zero-length only. (VOS)
If a FILEHANDLE is supplied, it must be writable and opened in append
-mode (i.e., use C<open(FH, '>>filename')>
+mode (i.e., use C<<< open(FH, '>>filename') >>>
or C<sysopen(FH,...,O_APPEND|O_RDWR)>. If a filename is supplied, it
should not be held open elsewhere. (Win32)
=item utime LIST
-Only the modification time is updated. (S<Mac OS>, VMS, S<RISC OS>)
+Only the modification time is updated. (S<BeOS>, S<Mac OS>, VMS, S<RISC OS>)
May not behave as expected. Behavior depends on the C runtime
library's implementation of utime(), and the filesystem being
=over 4
+=item v1.48, 02 February 2001
+
+Various updates from perl5-porters over the past year, supported
+platforms update from Jarkko Hietaniemi.
+
=item v1.47, 22 March 2000
Various cleanups from Tom Christiansen, including migration of
=head1 Supported Platforms
-As of early March 2000 (the Perl release 5.6.0), the following
+As of early 2001 (the Perl releases 5.6.1 and 5.7.1), the following
platforms are able to build Perl from the standard source code
-distribution available at http://www.perl.com/CPAN/src/index.html
+distribution available at http://www.cpan.org/src/index.html
AIX
+ AmigaOS
+ Darwin (Mac OS X)
+ DG/UX
DOS DJGPP 1)
+ DYNIX/ptx
EPOC
FreeBSD
HP-UX
IRIX
Linux
- LynxOS
MachTen
- MPE/iX
- NetBSD
+ MacOS Classic 2)
+ NonStop-UX
+ ReliantUNIX (SINIX)
OpenBSD
+ OpenVMS (VMS)
OS/2
+ OS X
QNX
- Rhapsody/Darwin 2)
- SCO SV
- SINIX
Solaris
- SVR4
- Tru64 UNIX 3)
+ Tru64 UNIX (DEC OSF/1, Digital UNIX)
UNICOS
UNICOS/mk
- Unixware
- VMS
VOS
- Windows 3.1 1)
- Windows 95 1) 4)
- Windows 98 1) 4)
- Windows NT 1) 4)
+ Win32/NT/2K 3)
1) in DOS mode either the DOS or OS/2 ports can be used
- 2) new in 5.6.0: the BSD/NeXT-based UNIX of Mac OS X
- 3) formerly known as Digital UNIX and before that DEC OSF/1
- 4) compilers: Borland, Cygwin, Mingw32 EGCS/GCC, VC++
+ 2) Mac OS Classic (pre-X) is almost 5.6.1-ready; building from
+ the source does work with 5.6.1, but additional MacOS specific
+ source code is needed for a complete build. See the web
+ site http://dev.macperl.org/ for more information.
+ 3) compilers: Borland, Cygwin, Mingw32 EGCS/GCC, VC++
-The following platforms worked for the previous major release
-(5.005_03 being the latest maintenance release of that, as of early
-March 2000), but be did not manage to test these in time for the 5.6.0
-release of Perl. There is a very good chance that these will work
-just fine with 5.6.0.
+The following platforms worked for the previous releases (5.6.0 and 5.7.0),
+but we did not manage to test these in time for the 5.7.1 release.
+There is a very good chance that these will work fine with the 5.7.1.
- A/UX
- BeOS
- BSD/OS
- DG/UX
- DYNIX/ptx
DomainOS
Hurd
- NextSTEP
- OpenSTEP
+ LynxOS
+ MinGW
+ MPE/iX
+ NetBSD
PowerMAX
- SCO ODT/OSR
+ SCO SV
SunOS
- Ultrix
+ SVR4
+ Unixware
+ Windows 3.1
+ Windows 95
+ Windows 98
+ Windows Me
-The following platform worked for the previous major release (5.005_03
-being the latest maintenance release of that, as of early March 2000).
-However, standardization on UTF-8 as the internal string representation
-in 5.6.0 has introduced incompatibilities in this EBCDIC platform.
-Support for this platform may be enabled in a future release:
+The following platform worked for the 5.005_03 major release but not
+for 5.6.0. Standardization on UTF-8 as the internal string
+representation in 5.6.0 and 5.6.1 introduced incompatibilities in this
+EBCDIC platform. While Perl 5.7.1 will build on this platform some
+regression tests may fail and the C<use utf8;> pragma typically
+introduces text handling errors.
- OS390 1)
+ OS/390 1)
- 1) Previously known as MVS, or OpenEdition MVS.
+ 1) previously known as MVS, about to become z/OS.
-Strongly related to the OS390 platform by also being EBCDIC-based
+Strongly related to the OS/390 platform by also being EBCDIC-based
mainframe platforms are the following platforms:
- BS2000
+ POSIX-BC (BS2000)
VM/ESA
-These are also not expected to work under 5.6.0 for the same reasons
-as OS390. Contact the mailing list perl-mvs@perl.org for more details.
-
-MacOS (Classic, pre-X) is almost 5.6.0-ready; building from the source
-does work with 5.6.0, but additional MacOS specific source code is needed
-for a complete port. Contact the mailing list macperl-porters@macperl.org
-for more information.
+These are also expected to work, albeit with no UTF-8 support, under 5.6.1
+for the same reasons as OS/390. Contact the mailing list perl-mvs@perl.org
+for more details.
The following platforms have been known to build Perl from source in
-the past, but we haven't been able to verify their status for the
-current release, either because the hardware/software platforms are
-rare or because we don't have an active champion on these
-platforms--or both:
+the past (5.005_03 and earlier), but we haven't been able to verify
+their status for the current release, either because the
+hardware/software platforms are rare or because we don't have an
+active champion on these platforms--or both. They used to work,
+though, so go ahead and try compiling them, and let perlbug@perl.org
+of any trouble.
3b1
- AmigaOS
+ A/UX
+ BeOS
+ BSD/OS
ConvexOS
CX/UX
DC/OSx
MiNT
MPC
NEWS-OS
+ NextSTEP
+ OpenSTEP
Opus
Plan 9
PowerUX
RISC/os
+ SCO ODT/OSR
Stellar
SVR2
TI1500
TitanOS
+ Ultrix
Unisys Dynix
Unixware
+ UTS
Support for the following platform is planned for a future Perl release:
Netware
The following platforms have their own source code distributions and
-binaries available via http://www.perl.com/CPAN/ports/index.html:
+binaries available via http://www.cpan.org/ports/index.html:
Perl release
- AS/400 5.003
Netware 5.003_07
+ OS/400 5.005_02
Tandem Guardian 5.004
The following platforms have only binaries available via
-http://www.perl.com/CPAN/ports/index.html :
+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.perl.com/CPAN/ports/index.html for binary distributions.
+http://www.cpan.org/ports/index.html for binary distributions.
=head1 SEE ALSO
-L<perlaix>, L<perlamiga>, L<perlcygwin>, L<perldos>, L<perlepoc>,
-L<perlebcdic>, L<perlhpux>, L<perlos2>, L<perlos390>, L<perlposix-bc>,
-L<perlwin32>, L<perlvms>, L<perlvos>, and L<Win32>.
+L<perlaix>, L<perlapollo>, L<perlamiga>, L<perlbeos>, L<perlbs200>,
+L<perlce>, L<perlcygwin>, L<perldgux>, L<perldos>, L<perlepoc>, L<perlebcdic>,
+L<perlhurd>, L<perlhpux>, L<perlmachten>, L<perlmacos>, L<perlmint>,
+L<perlmpeix>, L<perlnetware>, L<perlos2>, L<perlos390>, L<perlplan9>,
+L<perlqnx>, L<perlsolaris>, L<perltru64>, L<perlunicode>,
+L<perlvmesa>, L<perlvms>, L<perlvos>, L<perlwin32>, and L<Win32>.
=head1 AUTHORS / CONTRIBUTORS
-Abigail <abigail@fnx.com>,
+Abigail <abigail@foad.org>,
Charles Bailey <bailey@newman.upenn.edu>,
Graham Barr <gbarr@pobox.com>,
Tom Christiansen <tchrist@perl.com>,
-Nicholas Clark <Nicholas.Clark@liverpool.ac.uk>,
+Nicholas Clark <nick@ccl4.org>,
Thomas Dorner <Thomas.Dorner@start.de>,
-Andy Dougherty <doughera@lafcol.lafayette.edu>,
-Dominic Dunlop <domo@vo.lu>,
-Neale Ferguson <neale@mailbox.tabnsw.com.au>,
+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@cus.cam.ac.uk>,
+M.J.T. Guy <mjtg@cam.ac.uk>,
Jarkko Hietaniemi <jhi@iki.fi>,
Luther Huffman <lutherh@stratcom.com>,
-Nick Ing-Simmons <nick@ni-s.u-net.com>,
-Andreas J. KE<ouml>nig <koenig@kulturbox.de>,
+Nick Ing-Simmons <nick@ing-simmons.net>,
+Andreas J. KE<ouml>nig <a.koenig@mind.de>,
Markus Laker <mlaker@contax.co.uk>,
Andrew M. Langmead <aml@world.std.com>,
Larry Moore <ljmoore@freespace.net>,
Paul Moore <Paul.Moore@uk.origin-it.com>,
Chris Nandor <pudge@pobox.com>,
Matthias Neeracher <neeri@iis.ee.ethz.ch>,
+Philip Newton <pne@cpan.org>,
Gary Ng <71564.1743@CompuServe.COM>,
Tom Phoenix <rootbeer@teleport.com>,
AndrE<eacute> Pirard <A.Pirard@ulg.ac.be>,
Gurusamy Sarathy <gsar@activestate.com>,
Paul J. Schinder <schinder@pobox.com>,
Michael G Schwern <schwern@pobox.com>,
-Dan Sugalski <sugalskd@ous.edu>,
+Dan Sugalski <dan@sidhe.org>,
Nathan Torkington <gnat@frii.com>.
-This document is maintained by Chris Nandor
-<pudge@pobox.com>.
-
=head1 VERSION
-Version 1.47, last modified 22 March 2000
+Version 1.50, last modified 10 Jul 2001
projects / p5sagit/p5-mst-13.2.git / blobdiff