X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=vms%2Fperlvms.pod;h=11634248ec4ba4da226d27a935fc6672d3ea3b1f;hb=82dd182c2bf394910b632e03347f2df0d4480061;hp=9067917bb3371c37d4c86b27cf1dc3d40b6ceb7b;hpb=773da73dfa33b0e98b1b569c181e560f7f7a579f;p=p5sagit%2Fp5-mst-13.2.git diff --git a/vms/perlvms.pod b/vms/perlvms.pod index 9067917..1163424 100644 --- a/vms/perlvms.pod +++ b/vms/perlvms.pod @@ -121,7 +121,7 @@ directory, and the procedure for building the extension is simply I The procedure by which extensions are built and tested creates several levels (at least 4) under the directory in which the extension's source files live. -For this reason if you are runnning a version of VMS prior +For this reason if you are running a version of VMS prior to V7.1 you shouldn't nest the source directory too deeply in your directory structure lest you exceed RMS' maximum of 8 levels of subdirectory in a filespec. (You @@ -194,12 +194,88 @@ provided in the C package for explicit interconversion between VMS and Unix syntax; its documentation provides more details. -Filenames are, of course, still case-insensitive. For -consistency, most Perl routines return filespecs using -lower case letters only, regardless of the case used in -the arguments passed to them. (This is true only when -running under VMS; Perl respects the case-sensitivity -of OSs like Unix.) +Perl is now in the process of evolving to follow the setting of +the DECC$* feature logical names in the interpretation of UNIX pathnames. +This is still a work in progress. + +For handling extended characters, and case sensitivity, as long as +DECC$POSIX_COMPLIANT_PATHNAMES, DECC$FILENAME_UNIX_REPORT, and +DECC$FILENAME_UNIX_ONLY are not set, then the older Perl behavior +for conversions of file specifications from UNIX to VMS is followed, +except that VMS paths with concealed rooted logical names are now +translated correctly to UNIX paths. + +With those features set, then new routines may handle the translation, +because some of the rules are different. The presence of ./.../ +in a UNIX path is no longer translated to the VMS [...]. It will +translate to [.^.^.^.]. To be compatible with what MakeMaker expects, +if a VMS path can not be translated to a UNIX path when unixify +is called, it is passed through unchanged. So unixify("[...]") will +return "[...]". + +The handling of extended characters will also be better with the +newer translation routines. But more work is needed to fully support +extended file syntax names. In particular, at this writing Pathtools +can not deal with directories containing some extended characters. + +There are several ambiguous cases where a conversion routine can not +determine if an input filename is in UNIX format or in VMS format, +since now both VMS UNIX file specifications can have characters in +them that could be mistaken for syntax delimiters of the other type. +So some pathnames simply can not be used in a mode that allows either +type of pathname to be present. + +Perl will tend to assume that an ambiguous filename is in UNIX format. + +Allowing "." as a version delimiter is simply incompatible with +determining if a pathname is already VMS format or UNIX with the +extended file syntax. There is no way to know if "perl-5.8.6" that +TAR produces is a UNIX "perl-5.8.6" or a VMS "perl-5.8;6" when +passing it to unixify() or vmsify(). + +The DECC$FILENAME_UNIX_REPORT or the DECC$FILENAME_UNIX_ONLY logical +names control how Perl interprets filenames. + +The DECC$FILENAME_UNIX_ONLY setting has not been tested at this time. +Perl uses traditional OpenVMS file specifications internally and in +the test harness, so this mode may have limited use, or require more +changes to make usable. + +Everything about DECC$FILENAME_UNIX_REPORT should be assumed to apply +to DECC$FILENAME_UNIX_ONLY mode. The DECC$FILENAME_UNIX_ONLY differs +in that it expects all filenames passed to the C runtime to be already +in UNIX format. + +Again, currently most of the core Perl modules have not yet been updated +to understand that VMS is not as limited as it use to be. Fixing that +is a work in progress. + +The logical name DECC$POSIX_COMPLIANT_PATHNAMES is new with the +RMS Symbolic Link SDK. This version of Perl does not support it being set. + + +Filenames are case-insensitive on VAX, and on ODS-2 formatted +volumes on ALPHA and I64. + +On ODS-5 volumes filenames are case preserved and on newer +versions of OpenVMS can be optionally case sensitive. + +On ALPHA and I64, Perl is in the process of being changed to follow the +process case sensitivity setting to report if the file system is case +sensitive. + +Perl programs should not assume that VMS is case blind, or that +filenames will be in lowercase. + +Programs should use the File::Spec:case_tolerant setting to determine +the state, and not the $^O setting. + +For consistency, when the above feature is clear and when not +otherwise overridden by DECC feature logical names, most Perl routines +return file specifications using lower case letters only, +regardless of the case used in the arguments passed to them. +(This is true only when running under VMS; Perl respects the +case-sensitivity of OSs like Unix.) We've tried to minimize the dependence of Perl library modules on Unix syntax, but you may find that some of these, @@ -209,6 +285,11 @@ require that you use Unix syntax, since they will assume that of this in the Perl distribution itself, please let us know, so we can try to work around them. +Also when working on Perl programs on VMS, if you need a syntax +in a specific operating system format, then you need to either +check the appropriate DECC$ feature logical, or call a conversion +routine to force it to that format. + =head2 Wildcard expansion File specifications containing wildcards are allowed both on @@ -251,6 +332,7 @@ the behavior of glob expansion performed by Unix shells.) Similarly, the resultant filespec will contain the file version only if one was present in the input filespec. + =head2 Pipes Input and output pipes to Perl filehandles are supported; the @@ -285,6 +367,63 @@ The PERL5LIB and PERLLIB logical names work as documented in L, except that the element separator is '|' instead of ':'. The directory specifications may use either VMS or Unix syntax. +=head1 The Perl Forked Debugger + +The Perl forked debugger places the debugger commands and output in a +separate X-11 terminal window so that commands and output from multiple +processes are not mixed together. + +Perl on VMS supports an emulation of the forked debugger when Perl is +run on a VMS system that has X11 support installed. + +To use the forked debugger, you need to have the default display set to an +X-11 Server and some environment variables set that Unix expects. + +The forked debugger requires the environment variable C to be C, +and the environment variable C to exist. C must be in +lower case. + + $define TERM "xterm" + + $define DISPLAY "hostname:0.0" + +Currently the value of C is ignored. It is recommended that it be set +to be the hostname of the display, the server and screen in UNIX notation. In +the future the value of DISPLAY may be honored by Perl instead of using the +default display. + +It may be helpful to always use the forked debugger so that script I/O is +separated from debugger I/O. You can force the debugger to be forked by +assigning a value to the logical name that is not a process +identification number. + + $define PERLDB_PIDS XXXX + + +=head1 PERL_VMS_EXCEPTION_DEBUG + +The PERL_VMS_EXCEPTION_DEBUG being defined as "ENABLE" will cause the VMS +debugger to be invoked if a fatal exception that is not otherwise +handled is raised. The purpose of this is to allow debugging of +internal Perl problems that would cause such a condition. + +This allows the programmer to look at the execution stack and variables to +find out the cause of the exception. As the debugger is being invoked as +the Perl interpreter is about to do a fatal exit, continuing the execution +in debug mode is usally not practical. + +Starting Perl in the VMS debugger may change the program execution +profile in a way that such problems are not reproduced. + +The C function can be used to test this functionality from within +a program. + +In typical VMS style, only the first letter of the value of this logical +name is actually checked in a case insensitive mode, and it is considered +enabled if it is the value "T","1" or "E". + +This logical name must be defined before Perl is started. + =head1 Command line =head2 I/O redirection and backgrounding @@ -308,11 +447,15 @@ CEfile> appends stdout to C, =item * -C<2Efile> writes stderr to C, and +C<2Efile> writes stderr to C, + +=item * + +C<2EEfile> appends stderr to C, and =item * -C<2EEfile> appends stderr to C. +C<< 2>&1 >> redirects stderr to stdout. =back @@ -333,6 +476,10 @@ to pass uppercase switches to Perl, you need to enclose them in double-quotes on the command line, since the CRTL downcases all unquoted strings. +On newer 64 bit versions of OpenVMS, a process setting now +controls if the quoting is needed to preserve the case of +command line arguments. + =over 4 =item -i @@ -423,6 +570,37 @@ your copy of Perl: getsockopt, listen, recv, select(system call)*, send, setsockopt, shutdown, socket +The following function is available on Perls built on 64 bit OpenVMS 8.2 +with hard links enabled on an ODS-5 formatted build disk. If someone with +an OpenVMS 7.3-1 system were to modify configure.com and test the results, +this feature can be brought back to OpenVMS 7.3-1 and later. Hardlinks +must be enabled on the build disk because if the build procedure sees +this feature enabled, it uses it. + + link + +The following functions are available on Perls built on 64 bit OpenVMS +8.2 and can be implemented on OpenVMS 7.3-2 if someone were to modify +configure.com and test the results. (While in the build, at the time +of this writing, they have not been specifically tested.) + + getgrgid, getgrnam, getpwnam, getpwuid, + setgrent, ttyname + +The following functions are available on Perls built on 64 bit OpenVMS 8.2 +and later. (While in the build, at the time of this writing, they have +not been specifically tested.) + + statvfs, socketpair + +The following functions are expected to soon be available on Perls built +on 64 bit OpenVMS 8.2 or later with the RMS Symbolic link package. Use +of symbolic links at this time effectively requires the +DECC$POSIX_COMPLIANT_PATHNAMES to defined as 3, and operating in a +DECC$FILENAME_UNIX_REPORT mode. + + lchown, link, lstat, readlink, symlink + =over 4 =item File tests @@ -442,6 +620,9 @@ st_mode field. Finally, C<-d> returns true if passed a device specification without an explicit directory (e.g. C), as well as if passed a directory. +There are DECC feature logical names AND ODS-5 volume attributes that +also control what values are returned for the date fields. + Note: Some sites have reported problems when using the file-access tests (C<-r>, C<-w>, and C<-x>) on files accessed via DEC's DFS. Specifically, since DFS does not currently provide access to the @@ -503,6 +684,45 @@ C to insure that you'll get the proper value: return 1; } + +=item die + +C will force the native VMS exit status to be an SS$_ABORT code +if neither of the $! or $? status values are ones that would cause +the native status to be interpreted as being what VMS classifies as +SEVERE_ERROR severity for DCL error handling. + +When the future POSIX_EXIT mode is active, C, the native VMS exit +status value will have either one of the C<$!> or C<$?> or C<$^E> or +the UNIX value 255 encoded into it in a way that the effective original +value can be decoded by other programs written in C, including Perl +and the GNV package. As per the normal non-VMS behavior of C if +either C<$!> or C<$?> are non-zero, one of those values will be +encoded into a native VMS status value. If both of the UNIX status +values are 0, and the C<$^E> value is set one of ERROR or SEVERE_ERROR +severity, then the C<$^E> value will be used as the exit code as is. +If none of the above apply, the UNIX value of 255 will be encoded into +a native VMS exit status value. + +Please note a significant difference in the behavior of C in +the future POSIX_EXIT mode is that it does not force a VMS +SEVERE_ERROR status on exit. The UNIX exit values of 2 through +255 will be encoded in VMS status values with severity levels of +SUCCESS. The UNIX exit value of 1 will be encoded in a VMS status +value with a severity level of ERROR. This is to be compatible with +how the VMS C library encodes these values. + +The minimum severity level set by C in a future POSIX_EXIT mode +may be changed to be ERROR or higher before that mode becomes fully active +depending on the results of testing and further review. If this is +done, the behavior of c in the future POSIX_EXIT will close enough +to the default mode that most DCL shell scripts will probably not notice +a difference. + +See C<$?> for a description of the encoding of the UNIX value to +produce a native VMS status containing it. + + =item dump Rather than causing Perl to abort and dump core, the C @@ -689,11 +909,15 @@ change the file protection to delete the file, and you interrupt it in midstream, the file may be left intact, but with a changed ACL allowing you delete access. +This behavior of C is to be compatible with POSIX behavior +and not traditional VMS behavior. + =item utime LIST -Since ODS-2, the VMS file structure for disk files, does not keep -track of access times, this operator changes only the modification -time of the file (VMS revision date). +This operator changes only the modification time of the file (VMS +revision date) on ODS-2 volumes and ODS-5 volumes without access +dates enabled. On ODS-5 volumes with access dates enabled, the +true access time is modified. =item waitpid PID,FLAGS @@ -845,7 +1069,7 @@ a fatal error. This is equivalent to doing the following from DCL: DELETE/LOGICAL * You can imagine how bad things would be if, for example, the SYS$MANAGER -or SYS$SYSTEM logicals were deleted. +or SYS$SYSTEM logical names were deleted. At present, the first time you iterate over %ENV using C, or C, you will incur a time penalty as all @@ -854,12 +1078,13 @@ Subsequent iterations will not reread logical names, so they won't be as slow, but they also won't reflect any changes to logical name tables caused by other programs. -You do need to be careful with the logicals representing process-permanent -files, such as C and C. The translations for these -logicals are prepended with a two-byte binary value (0x1B 0x00) that needs to be -stripped off if you want to use it. (In previous versions of Perl it wasn't -possible to get the values of these logicals, as the null byte acted as an -end-of-string marker) +You do need to be careful with the logical names representing +process-permanent files, such as C and C. +The translations for these logical names are prepended with a +two-byte binary value (0x1B 0x00) that needs to be stripped off +if you wantto use it. (In previous versions of Perl it wasn't +possible to get the values of these logical names, as the null +byte acted as an end-of-string marker) =item $! @@ -882,6 +1107,9 @@ is the value of vaxc$errno, and its string value is the corresponding VMS message string, as retrieved by sys$getmsg(). Setting C<$^E> sets vaxc$errno to the value specified. +While Perl attempts to keep the vaxc$errno value to be current, if +errno is not EVMSERR, it may not be from the current operation. + =item $? The "status value" returned in C<$?> is synthesized from the @@ -890,23 +1118,80 @@ POSIX wait(5) semantics, in order to allow Perl programs to portably test for successful completion of subprocesses. The low order 8 bits of C<$?> are always 0 under VMS, since the termination status of a process may or may not have been -generated by an exception. The next 8 bits are derived from -the severity portion of the subprocess' exit status: if the -severity was success or informational, these bits are all 0; -if the severity was warning, they contain a value of 1; if the -severity was error or fatal error, they contain the actual -severity bits, which turns out to be a value of 2 for error -and 4 for fatal error. +generated by an exception. + +The next 8 bits contain the termination status of the program. + +If the child process follows the convention of C programs +compiled with the _POSIX_EXIT macro set, the status value will +contain the actual value of 0 to 255 returned by that program +on a normal exit. + +With the _POSIX_EXIT macro set, the UNIX exit value of zero is +represented as a VMS native status of 1, and the UNIX values +from 2 to 255 are encoded by the equation: + + VMS_status = 0x35a000 + (unix_value * 8) + 1. + +And in the special case of unix value 1 the encoding is: + + VMS_status = 0x35a000 + 8 + 2 + 0x10000000. + +For other termination statuses, the severity portion of the +subprocess' exit status is used: if the severity was success or +informational, these bits are all 0; if the severity was +warning, they contain a value of 1; if the severity was +error or fatal error, they contain the actual severity bits, +which turns out to be a value of 2 for error and 4 for severe_error. +Fatal is another term for the severe_error status. As a result, C<$?> will always be zero if the subprocess' exit status indicated successful completion, and non-zero if a -warning or error occurred. Conversely, when setting C<$?> in -an END block, an attempt is made to convert the POSIX value -into a native status intelligible to the operating system upon -exiting Perl. What this boils down to is that setting C<$?> -to zero results in the generic success value SS$_NORMAL, and -setting C<$?> to a non-zero value results in the generic -failure status SS$_ABORT. See also L. +warning or error occurred or a program compliant with encoding +_POSIX_EXIT values was run and set a status. + +How can you tell the difference between a non-zero status that is +the result of a VMS native error status or an encoded UNIX status? +You can not unless you look at the ${^CHILD_ERROR_NATIVE} value. +The ${^CHILD_ERROR_NATIVE} value returns the actual VMS status value +and check the severity bits. If the severity bits are equal to 1, +then if the numeric value for C<$?> is between 2 and 255 or 0, then +C<$?> accurately reflects a value passed back from a UNIX application. +If C<$?> is 1, and the severity bits indicate a VMS error (2), then +C<$?> is from a UNIX application exit value. + +In practice, Perl scripts that call programs that return _POSIX_EXIT +type status values will be expecting those values, and programs that +call traditional VMS programs will either be expecting the previous +behavior or just checking for a non-zero status. + +And success is always the value 0 in all behaviors. + +When the actual VMS termination status of the child is an error, +internally the C<$!> value will be set to the closest UNIX errno +value to that error so that Perl scripts that test for error +messages will see the expected UNIX style error message instead +of a VMS message. + +Conversely, when setting C<$?> in an END block, an attempt is made +to convert the POSIX value into a native status intelligible to +the operating system upon exiting Perl. What this boils down to +is that setting C<$?> to zero results in the generic success value +SS$_NORMAL, and setting C<$?> to a non-zero value results in the +generic failure status SS$_ABORT. See also L. + +With the future POSIX_EXIT mode set, setting C<$?> will cause the +new value to also be encoded into C<$^E> so that the either the +original parent or child exit status values of 0 to 255 +can be automatically recovered by C programs expecting _POSIX_EXIT +behavior. If both a parent and a child exit value are non-zero, then it +will be assumed that this is actually a VMS native status value to +be passed through. The special value of 0xFFFF is almost a NOOP as +it will cause the current native VMS status in the C library to +become the current native Perl VMS status, and is handled this way +as consequence of it known to not be a valid native VMS status value. +It is recommend that only values in range of normal UNIX parent or +child status numbers, 0 to 255 are used. The pragma C makes C<$?> reflect the actual VMS exit status instead of the default emulation of POSIX status @@ -914,6 +1199,11 @@ described above. This pragma also disables the conversion of non-zero values to SS$_ABORT when setting C<$?> in an END block (but zero will still be converted to SS$_NORMAL). +Do not use the pragma C with the future +POSIX_EXIT mode, as they are at times requesting conflicting +actions and the consequence of ignoring this advice will be +undefined to allow future improvements in the POSIX exit handling. + =item $| Setting C<$|> for an I/O stream causes data to be flushed @@ -935,7 +1225,7 @@ problems. =head1 Revision date -This document was last updated on 01-May-2002, for Perl 5, +This document was last updated on 14-Oct-2005, for Perl 5, patchlevel 8. =head1 AUTHOR @@ -943,3 +1233,4 @@ patchlevel 8. Charles Bailey bailey@cor.newman.upenn.edu Craig Berry craigberry@mac.com Dan Sugalski dan@sidhe.org +John Malmberg wb8tyw@qsl.net