X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=pod%2Fperlport.pod;h=3458c7c581cb2782bd6da560fdac7283cfea2024;hb=af9e49b40a4cc2d6c0d5ebad7e84fb62143b24e1;hp=f4e6ddf06f6a65e5ab8a228d3c29264ca9980ecd;hpb=519bc77726e9fd6164d3ad64bae10fdea36cae2a;p=p5sagit%2Fp5-mst-13.2.git diff --git a/pod/perlport.pod b/pod/perlport.pod index f4e6ddf..3458c7c 100644 --- a/pod/perlport.pod +++ b/pod/perlport.pod @@ -360,7 +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 @@ -658,9 +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 @@ -1057,6 +1058,9 @@ MPW, ftp://ftp.apple.com/developer/Tool_Chest/Core_Mac_OS_Tools/ =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: @@ -1093,18 +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. -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 @@ -1115,7 +1180,8 @@ 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>, @@ -1126,6 +1192,10 @@ 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: @@ -1136,10 +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 @@ -1498,10 +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 @@ -1540,7 +1612,7 @@ suffixes. C<-S> is meaningless. (Win32) C<-x> (or C<-X>) determine if a file has an executable file type. (S) -=item atan2 Y,X +=item atan2 Due to issues with various CPUs, math libraries, compilers, and standards, results for C may vary depending on any combination of the above. @@ -1551,7 +1623,7 @@ run on does not allow it. (Tru64, HP-UX 10.20) The current version of the standards for C is available at L. -=item binmode FILEHANDLE +=item binmode Meaningless. (S, S) @@ -1562,7 +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) @@ -1577,7 +1649,7 @@ 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, S, S) @@ -1585,26 +1657,24 @@ Does nothing, but won't fail. (Win32) A little funky, because VOS's notion of ownership is a little funky (VOS). -=item chroot FILENAME - =item chroot 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) -=item dbmclose HASH +=item dbmclose Not implemented. (VMS, S, VOS) -=item dbmopen HASH,DBNAME,MODE +=item dbmopen Not implemented. (VMS, S, VOS) -=item dump LABEL +=item dump Not useful. (S, S) @@ -1612,7 +1682,7 @@ Not implemented. (Win32) Invokes VMS debugger. (VMS) -=item exec LIST +=item exec Not implemented. (S) @@ -1621,8 +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 @@ -1630,13 +1698,19 @@ mapping the C<1> to SS$_ABORT (C<44>). This behavior may be overridden with the pragma C. As with the CRTL's exit() function, C 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) +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. (VMS) -=item fcntl FILEHANDLE,FUNCTION,SCALAR +=item fcntl -Not implemented. (Win32, VMS) +Not implemented. (Win32) +Some functions available based on the version of VMS. (VMS) -=item flock FILEHANDLE,OPERATION +=item flock Not implemented (S, VMS, S, VOS). @@ -1655,7 +1729,7 @@ Does not automatically flush output handles on some platforms. Not implemented. (S, S) -=item getpgrp PID +=item getpgrp Not implemented. (S, Win32, VMS, S) @@ -1663,43 +1737,43 @@ Not implemented. (S, Win32, VMS, S) Not implemented. (S, Win32, S) -=item getpriority WHICH,WHO +=item getpriority Not implemented. (S, Win32, VMS, S, VOS, VM/ESA) -=item getpwnam NAME +=item getpwnam Not implemented. (S, Win32) Not useful. (S) -=item getgrnam NAME +=item getgrnam Not implemented. (S, Win32, VMS, S) -=item getnetbyname NAME +=item getnetbyname Not implemented. (S, Win32, S) -=item getpwuid UID +=item getpwuid Not implemented. (S, Win32) Not useful. (S) -=item getgrgid GID +=item getgrgid Not implemented. (S, Win32, VMS, S) -=item getnetbyaddr ADDR,ADDRTYPE +=item getnetbyaddr Not implemented. (S, Win32, S) -=item getprotobynumber NUMBER +=item getprotobynumber Not implemented. (S) -=item getservbyport PORT,PROTO +=item getservbyport Not implemented. (S) @@ -1732,19 +1806,19 @@ Not implemented. (S, Win32, S) Not implemented. (Win32, S) -=item sethostent STAYOPEN +=item sethostent Not implemented. (S, Win32, S, S) -=item setnetent STAYOPEN +=item setnetent Not implemented. (S, Win32, S, S) -=item setprotoent STAYOPEN +=item setprotoent Not implemented. (S, Win32, S, S) -=item setservent STAYOPEN +=item setservent Not implemented. (S, Win32, S) @@ -1776,13 +1850,15 @@ Not implemented. (S, Win32) Not implemented. (S) -=item glob EXPR - =item glob This operator is implemented via the File::Glob extension on most platforms. See L for portability information. +=item gmtime + +Same portability caveats as L. + =item ioctl FILEHANDLE,FUNCTION,SCALAR Not implemented. (VMS) @@ -1792,7 +1868,7 @@ in the Winsock API does. (Win32) Available only for socket handles. (S) -=item kill SIGNAL, LIST +=item kill C is implemented for the sake of taint checking; use with other signals is unimplemented. (S) @@ -1806,9 +1882,12 @@ and makes it exit immediately with exit status $sig. As in Unix, if $sig is 0 and the specified process exists, it returns true without actually terminating it. (Win32) -=item link OLDFILE,NEWFILE +Is not supported for process identification number of 0 or negative +numbers. (VMS) -Not implemented. (S, MPE/iX, VMS, S) +=item link + +Not implemented. (S, MPE/iX, S) Link count not updated because hard links are not quite that hard (They are sort of half-way between hard and soft links). (AmigaOS) @@ -1816,29 +1895,32 @@ Link count not updated because hard links are not quite that hard Hard links are implemented on Win32 (Windows NT and Windows 2000) under NTFS only. -=item lstat FILEHANDLE +Available on 64 bit OpenVMS 8.2 and later. (VMS) + +=item localtime -=item lstat EXPR +Because Perl currently relies on the native standard C localtime() +function, it is only safe to use times between 0 and (2**31)-1. Times +outside this range may result in unexpected behavior depending on your +operating system's implementation of localtime(). =item lstat -Not implemented. (VMS, S) +Not implemented. (S) Return values (especially for device and inode) may be bogus. (Win32) -=item msgctl ID,CMD,ARG +=item msgctl -=item msgget KEY,FLAGS +=item msgget -=item msgsnd ID,MSG,FLAGS +=item msgsnd -=item msgrcv ID,VAR,SIZE,TYPE,FLAGS +=item msgrcv Not implemented. (S, Win32, VMS, S, S, VOS) -=item open FILEHANDLE,EXPR - -=item open FILEHANDLE +=item open The C<|> variants are supported only if ToolServer is installed. (S) @@ -1848,21 +1930,19 @@ open to C<|-> and C<-|> are unsupported. (S, Win32, S) Opening a process does not automatically flush output handles on some platforms. (SunOS, Solaris, HP-UX) -=item pipe READHANDLE,WRITEHANDLE +=item pipe Very limited functionality. (MiNT) -=item readlink EXPR - =item readlink Not implemented. (Win32, VMS, S) -=item rename OLDNAME,NEWNAME +=item rename Can't move directories between directories on different logical volumes. (Win32) -=item select RBITS,WBITS,EBITS,TIMEOUT +=item select Only implemented on sockets. (Win32, VMS) @@ -1870,11 +1950,11 @@ Only reliable on sockets. (S) Note that the C