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e518068a | 1 | =head1 NAME |
2 | ||
3 | perlvms - VMS-specific documentation for Perl | |
4 | ||
5 | =head1 DESCRIPTION | |
a0d0e21e | 6 | |
748a9306 LW |
7 | Gathered below are notes describing details of Perl 5's |
8 | behavior on VMS. They are a supplement to the regular Perl 5 | |
9 | documentation, so we have focussed on the ways in which Perl | |
10 | 5 functions differently under VMS than it does under Unix, | |
11 | and on the interactions between Perl and the rest of the | |
a0d0e21e | 12 | operating system. We haven't tried to duplicate complete |
748a9306 | 13 | descriptions of Perl features from the main Perl |
a0d0e21e | 14 | documentation, which can be found in the F<[.pod]> |
748a9306 | 15 | subdirectory of the Perl distribution. |
a0d0e21e LW |
16 | |
17 | We hope these notes will save you from confusion and lost | |
748a9306 | 18 | sleep when writing Perl scripts on VMS. If you find we've |
a0d0e21e | 19 | missed something you think should appear here, please don't |
9bc98430 | 20 | hesitate to drop a line to vmsperl@perl.org. |
a0d0e21e | 21 | |
4e592037 | 22 | =head1 Installation |
23 | ||
24 | Directions for building and installing Perl 5 can be found in | |
25 | the file F<README.vms> in the main source directory of the | |
26 | Perl distribution.. | |
27 | ||
e518068a | 28 | =head1 Organization of Perl Images |
748a9306 | 29 | |
e518068a | 30 | =head2 Core Images |
748a9306 LW |
31 | |
32 | During the installation process, three Perl images are produced. | |
33 | F<Miniperl.Exe> is an executable image which contains all of | |
34 | the basic functionality of Perl, but cannot take advantage of | |
35 | Perl extensions. It is used to generate several files needed | |
36 | to build the complete Perl and various extensions. Once you've | |
37 | finished installing Perl, you can delete this image. | |
38 | ||
39 | Most of the complete Perl resides in the shareable image | |
40 | F<PerlShr.Exe>, which provides a core to which the Perl executable | |
41 | image and all Perl extensions are linked. You should place this | |
42 | image in F<Sys$Share>, or define the logical name F<PerlShr> to | |
43 | translate to the full file specification of this image. It should | |
44 | be world readable. (Remember that if a user has execute only access | |
45 | to F<PerlShr>, VMS will treat it as if it were a privileged shareable | |
46 | image, and will therefore require all downstream shareable images to be | |
47 | INSTALLed, etc.) | |
48 | ||
49 | ||
50 | Finally, F<Perl.Exe> is an executable image containing the main | |
51 | entry point for Perl, as well as some initialization code. It | |
52 | should be placed in a public directory, and made world executable. | |
53 | In order to run Perl with command line arguments, you should | |
54 | define a foreign command to invoke this image. | |
55 | ||
56 | =head2 Perl Extensions | |
57 | ||
58 | Perl extensions are packages which provide both XS and Perl code | |
59 | to add new functionality to perl. (XS is a meta-language which | |
60 | simplifies writing C code which interacts with Perl, see | |
2ceaccd7 | 61 | L<perlxs> for more details.) The Perl code for an |
748a9306 LW |
62 | extension is treated like any other library module - it's |
63 | made available in your script through the appropriate | |
64 | C<use> or C<require> statement, and usually defines a Perl | |
65 | package containing the extension. | |
66 | ||
67 | The portion of the extension provided by the XS code may be | |
68 | connected to the rest of Perl in either of two ways. In the | |
69 | B<static> configuration, the object code for the extension is | |
70 | linked directly into F<PerlShr.Exe>, and is initialized whenever | |
71 | Perl is invoked. In the B<dynamic> configuration, the extension's | |
72 | machine code is placed into a separate shareable image, which is | |
73 | mapped by Perl's DynaLoader when the extension is C<use>d or | |
74 | C<require>d in your script. This allows you to maintain the | |
75 | extension as a separate entity, at the cost of keeping track of the | |
76 | additional shareable image. Most extensions can be set up as either | |
77 | static or dynamic. | |
78 | ||
79 | The source code for an extension usually resides in its own | |
80 | directory. At least three files are generally provided: | |
81 | I<Extshortname>F<.xs> (where I<Extshortname> is the portion of | |
82 | the extension's name following the last C<::>), containing | |
83 | the XS code, I<Extshortname>F<.pm>, the Perl library module | |
84 | for the extension, and F<Makefile.PL>, a Perl script which uses | |
85 | the C<MakeMaker> library modules supplied with Perl to generate | |
86 | a F<Descrip.MMS> file for the extension. | |
87 | ||
e518068a | 88 | =head2 Installing static extensions |
748a9306 LW |
89 | |
90 | Since static extensions are incorporated directly into | |
91 | F<PerlShr.Exe>, you'll have to rebuild Perl to incorporate a | |
92 | new extension. You should edit the main F<Descrip.MMS> or F<Makefile> | |
93 | you use to build Perl, adding the extension's name to the C<ext> | |
94 | macro, and the extension's object file to the C<extobj> macro. | |
95 | You'll also need to build the extension's object file, either | |
96 | by adding dependencies to the main F<Descrip.MMS>, or using a | |
97 | separate F<Descrip.MMS> for the extension. Then, rebuild | |
98 | F<PerlShr.Exe> to incorporate the new code. | |
99 | ||
100 | Finally, you'll need to copy the extension's Perl library | |
101 | module to the F<[.>I<Extname>F<]> subdirectory under one | |
102 | of the directories in C<@INC>, where I<Extname> is the name | |
103 | of the extension, with all C<::> replaced by C<.> (e.g. | |
104 | the library module for extension Foo::Bar would be copied | |
105 | to a F<[.Foo.Bar]> subdirectory). | |
106 | ||
e518068a | 107 | =head2 Installing dynamic extensions |
108 | ||
109 | In general, the distributed kit for a Perl extension includes | |
110 | a file named Makefile.PL, which is a Perl program which is used | |
111 | to create a F<Descrip.MMS> file which can be used to build and | |
112 | install the files required by the extension. The kit should be | |
c07a80fd | 113 | unpacked into a directory tree B<not> under the main Perl source |
e518068a | 114 | directory, and the procedure for building the extension is simply |
115 | ||
e518068a | 116 | $ perl Makefile.PL ! Create Descrip.MMS |
117 | $ mmk ! Build necessary files | |
118 | $ mmk test ! Run test code, if supplied | |
119 | $ mmk install ! Install into public Perl tree | |
120 | ||
c07a80fd | 121 | I<N.B.> The procedure by which extensions are built and |
122 | tested creates several levels (at least 4) under the | |
123 | directory in which the extension's source files live. | |
d7f8936a | 124 | For this reason if you are running a version of VMS prior |
773da73d JH |
125 | to V7.1 you shouldn't nest the source directory |
126 | too deeply in your directory structure lest you exceed RMS' | |
c07a80fd | 127 | maximum of 8 levels of subdirectory in a filespec. (You |
128 | can use rooted logical names to get another 8 levels of | |
129 | nesting, if you can't place the files near the top of | |
130 | the physical directory structure.) | |
e518068a | 131 | |
132 | VMS support for this process in the current release of Perl | |
133 | is sufficient to handle most extensions. However, it does | |
134 | not yet recognize extra libraries required to build shareable | |
135 | images which are part of an extension, so these must be added | |
136 | to the linker options file for the extension by hand. For | |
137 | instance, if the F<PGPLOT> extension to Perl requires the | |
138 | F<PGPLOTSHR.EXE> shareable image in order to properly link | |
139 | the Perl extension, then the line C<PGPLOTSHR/Share> must | |
140 | be added to the linker options file F<PGPLOT.Opt> produced | |
141 | during the build process for the Perl extension. | |
142 | ||
773da73d JH |
143 | By default, the shareable image for an extension is placed in |
144 | the F<[.lib.site_perl.auto>I<Arch>.I<Extname>F<]> directory of the | |
e518068a | 145 | installed Perl directory tree (where I<Arch> is F<VMS_VAX> or |
bbce6d69 | 146 | F<VMS_AXP>, and I<Extname> is the name of the extension, with |
147 | each C<::> translated to C<.>). (See the MakeMaker documentation | |
148 | for more details on installation options for extensions.) | |
4e592037 | 149 | However, it can be manually placed in any of several locations: |
773da73d JH |
150 | |
151 | =over 4 | |
152 | ||
153 | =item * | |
154 | ||
155 | the F<[.Lib.Auto.>I<Arch>I<$PVers>I<Extname>F<]> subdirectory | |
156 | of one of the directories in C<@INC> (where I<PVers> | |
157 | is the version of Perl you're using, as supplied in C<$]>, | |
158 | with '.' converted to '_'), or | |
159 | ||
160 | =item * | |
161 | ||
162 | one of the directories in C<@INC>, or | |
163 | ||
164 | =item * | |
165 | ||
166 | a directory which the extensions Perl library module | |
167 | passes to the DynaLoader when asking it to map | |
168 | the shareable image, or | |
169 | ||
170 | =item * | |
171 | ||
172 | F<Sys$Share> or F<Sys$Library>. | |
173 | ||
174 | =back | |
175 | ||
748a9306 LW |
176 | If the shareable image isn't in any of these places, you'll need |
177 | to define a logical name I<Extshortname>, where I<Extshortname> | |
178 | is the portion of the extension's name after the last C<::>, which | |
179 | translates to the full file specification of the shareable image. | |
180 | ||
4e592037 | 181 | =head1 File specifications |
748a9306 | 182 | |
4e592037 | 183 | =head2 Syntax |
a0d0e21e | 184 | |
748a9306 | 185 | We have tried to make Perl aware of both VMS-style and Unix- |
a0d0e21e LW |
186 | style file specifications wherever possible. You may use |
187 | either style, or both, on the command line and in scripts, | |
39aca757 | 188 | but you may not combine the two styles within a single file |
1c9f8daa | 189 | specification. VMS Perl interprets Unix pathnames in much |
190 | the same way as the CRTL (I<e.g.> the first component of | |
191 | an absolute path is read as the device name for the | |
192 | VMS file specification). There are a set of functions | |
193 | provided in the C<VMS::Filespec> package for explicit | |
194 | interconversion between VMS and Unix syntax; its | |
195 | documentation provides more details. | |
196 | ||
9296fdfa | 197 | Perl is now in the process of evolving to follow the setting of |
fb38d079 | 198 | the DECC$* feature logical names in the interpretation of UNIX pathnames. |
9296fdfa JM |
199 | This is still a work in progress. |
200 | ||
201 | For handling extended characters, and case sensitivity, as long as | |
202 | DECC$POSIX_COMPLIANT_PATHNAMES, DECC$FILENAME_UNIX_REPORT, and | |
203 | DECC$FILENAME_UNIX_ONLY are not set, then the older Perl behavior | |
204 | for conversions of file specifications from UNIX to VMS is followed, | |
fb38d079 | 205 | except that VMS paths with concealed rooted logical names are now |
9296fdfa JM |
206 | translated correctly to UNIX paths. |
207 | ||
208 | With those features set, then new routines may handle the translation, | |
209 | because some of the rules are different. The presence of ./.../ | |
210 | in a UNIX path is no longer translated to the VMS [...]. It will | |
211 | translate to [.^.^.^.]. To be compatible with what MakeMaker expects, | |
212 | if a VMS path can not be translated to a UNIX path when unixify | |
213 | is called, it is passed through unchanged. So unixify("[...]") will | |
214 | return "[...]". | |
215 | ||
216 | The handling of extended characters will also be better with the | |
217 | newer translation routines. But more work is needed to fully support | |
218 | extended file syntax names. In particular, at this writing Pathtools | |
219 | can not deal with directories containing some extended characters. | |
220 | ||
221 | There are several ambiguous cases where a conversion routine can not | |
222 | determine if an input filename is in UNIX format or in VMS format, | |
223 | since now both VMS UNIX file specifications can have characters in | |
224 | them that could be mistaken for syntax delimiters of the other type. | |
225 | So some pathnames simply can not be used in a mode that allows either | |
226 | type of pathname to be present. | |
227 | ||
228 | Perl will tend to assume that an ambiguous filename is in UNIX format. | |
229 | ||
230 | Allowing "." as a version delimiter is simply incompatible with | |
231 | determining if a pathname is already VMS format or UNIX with the | |
232 | extended file syntax. There is no way to know if "perl-5.8.6" that | |
233 | TAR produces is a UNIX "perl-5.8.6" or a VMS "perl-5.8;6" when | |
234 | passing it to unixify() or vmsify(). | |
235 | ||
236 | The DECC$FILENAME_UNIX_REPORT or the DECC$FILENAME_UNIX_ONLY logical | |
237 | names control how Perl interprets filenames. | |
238 | ||
239 | The DECC$FILENAME_UNIX_ONLY setting has not been tested at this time. | |
240 | Perl uses traditional OpenVMS file specifications internally and in | |
241 | the test harness, so this mode may have limited use, or require more | |
242 | changes to make usable. | |
243 | ||
244 | Everything about DECC$FILENAME_UNIX_REPORT should be assumed to apply | |
245 | to DECC$FILENAME_UNIX_ONLY mode. The DECC$FILENAME_UNIX_ONLY differs | |
246 | in that it expects all filenames passed to the C runtime to be already | |
247 | in UNIX format. | |
248 | ||
249 | Again, currently most of the core Perl modules have not yet been updated | |
250 | to understand that VMS is not as limited as it use to be. Fixing that | |
251 | is a work in progress. | |
252 | ||
253 | The logical name DECC$POSIX_COMPLIANT_PATHNAMES is new with the | |
254 | RMS Symbolic Link SDK. This version of Perl does not support it being set. | |
255 | ||
256 | ||
257 | Filenames are case-insensitive on VAX, and on ODS-2 formatted | |
258 | volumes on ALPHA and I64. | |
259 | ||
260 | On ODS-5 volumes filenames are case preserved and on newer | |
261 | versions of OpenVMS can be optionally case sensitive. | |
262 | ||
263 | On ALPHA and I64, Perl is in the process of being changed to follow the | |
264 | process case sensitivity setting to report if the file system is case | |
265 | sensitive. | |
266 | ||
267 | Perl programs should not assume that VMS is case blind, or that | |
268 | filenames will be in lowercase. | |
269 | ||
270 | Programs should use the File::Spec:case_tolerant setting to determine | |
271 | the state, and not the $^O setting. | |
272 | ||
273 | For consistency, when the above feature is clear and when not | |
fb38d079 | 274 | otherwise overridden by DECC feature logical names, most Perl routines |
9296fdfa JM |
275 | return file specifications using lower case letters only, |
276 | regardless of the case used in the arguments passed to them. | |
277 | (This is true only when running under VMS; Perl respects the | |
278 | case-sensitivity of OSs like Unix.) | |
a0d0e21e | 279 | |
748a9306 | 280 | We've tried to minimize the dependence of Perl library |
a0d0e21e LW |
281 | modules on Unix syntax, but you may find that some of these, |
282 | as well as some scripts written for Unix systems, will | |
283 | require that you use Unix syntax, since they will assume that | |
4e592037 | 284 | '/' is the directory separator, I<etc.> If you find instances |
748a9306 | 285 | of this in the Perl distribution itself, please let us know, |
a0d0e21e LW |
286 | so we can try to work around them. |
287 | ||
9296fdfa JM |
288 | Also when working on Perl programs on VMS, if you need a syntax |
289 | in a specific operating system format, then you need to either | |
290 | check the appropriate DECC$ feature logical, or call a conversion | |
291 | routine to force it to that format. | |
292 | ||
4e592037 | 293 | =head2 Wildcard expansion |
294 | ||
295 | File specifications containing wildcards are allowed both on | |
07698885 | 296 | the command line and within Perl globs (e.g. C<E<lt>*.cE<gt>>). If |
4e592037 | 297 | the wildcard filespec uses VMS syntax, the resultant |
298 | filespecs will follow VMS syntax; if a Unix-style filespec is | |
299 | passed in, Unix-style filespecs will be returned. | |
773da73d JH |
300 | Similar to the behavior of wildcard globbing for a Unix shell, |
301 | one can escape command line wildcards with double quotation | |
302 | marks C<"> around a perl program command line argument. However, | |
303 | owing to the stripping of C<"> characters carried out by the C | |
304 | handling of argv you will need to escape a construct such as | |
305 | this one (in a directory containing the files F<PERL.C>, F<PERL.EXE>, | |
306 | F<PERL.H>, and F<PERL.OBJ>): | |
307 | ||
308 | $ perl -e "print join(' ',@ARGV)" perl.* | |
309 | perl.c perl.exe perl.h perl.obj | |
310 | ||
311 | in the following triple quoted manner: | |
312 | ||
313 | $ perl -e "print join(' ',@ARGV)" """perl.*""" | |
314 | perl.* | |
4e592037 | 315 | |
773da73d JH |
316 | In both the case of unquoted command line arguments or in calls |
317 | to C<glob()> VMS wildcard expansion is performed. (csh-style | |
aa779de1 | 318 | wildcard expansion is available if you use C<File::Glob::glob>.) |
4e592037 | 319 | If the wildcard filespec contains a device or directory |
320 | specification, then the resultant filespecs will also contain | |
321 | a device and directory; otherwise, device and directory | |
322 | information are removed. VMS-style resultant filespecs will | |
323 | contain a full device and directory, while Unix-style | |
324 | resultant filespecs will contain only as much of a directory | |
325 | path as was present in the input filespec. For example, if | |
326 | your default directory is Perl_Root:[000000], the expansion | |
327 | of C<[.t]*.*> will yield filespecs like | |
328 | "perl_root:[t]base.dir", while the expansion of C<t/*/*> will | |
329 | yield filespecs like "t/base.dir". (This is done to match | |
330 | the behavior of glob expansion performed by Unix shells.) | |
331 | ||
332 | Similarly, the resultant filespec will contain the file version | |
333 | only if one was present in the input filespec. | |
334 | ||
9296fdfa | 335 | |
4e592037 | 336 | =head2 Pipes |
337 | ||
338 | Input and output pipes to Perl filehandles are supported; the | |
339 | "file name" is passed to lib$spawn() for asynchronous | |
340 | execution. You should be careful to close any pipes you have | |
341 | opened in a Perl script, lest you leave any "orphaned" | |
342 | subprocesses around when Perl exits. | |
343 | ||
344 | You may also use backticks to invoke a DCL subprocess, whose | |
345 | output is used as the return value of the expression. The | |
aa779de1 CB |
346 | string between the backticks is handled as if it were the |
347 | argument to the C<system> operator (see below). In this case, | |
348 | Perl will wait for the subprocess to complete before continuing. | |
4e592037 | 349 | |
376ae1f1 PP |
350 | The mailbox (MBX) that perl can create to communicate with a pipe |
351 | defaults to a buffer size of 512. The default buffer size is | |
1506e54c | 352 | adjustable via the logical name PERL_MBX_SIZE provided that the |
376ae1f1 PP |
353 | value falls between 128 and the SYSGEN parameter MAXBUF inclusive. |
354 | For example, to double the MBX size from the default within | |
1506e54c | 355 | a Perl program, use C<$ENV{'PERL_MBX_SIZE'} = 1024;> and then |
376ae1f1 PP |
356 | open and use pipe constructs. An alternative would be to issue |
357 | the command: | |
358 | ||
359 | $ Define PERL_MBX_SIZE 1024 | |
360 | ||
361 | before running your wide record pipe program. A larger value may | |
362 | improve performance at the expense of the BYTLM UAF quota. | |
363 | ||
4e592037 | 364 | =head1 PERL5LIB and PERLLIB |
365 | ||
39aca757 | 366 | The PERL5LIB and PERLLIB logical names work as documented in L<perl>, |
4e592037 | 367 | except that the element separator is '|' instead of ':'. The |
368 | directory specifications may use either VMS or Unix syntax. | |
369 | ||
9c1171d1 JM |
370 | =head1 PERL_VMS_EXCEPTION_DEBUG |
371 | ||
372 | The PERL_VMS_EXCEPTION_DEBUG being defined as "ENABLE" will cause the VMS | |
373 | debugger to be invoked if a fatal exception that is not otherwise | |
374 | handled is raised. The purpose of this is to allow debugging of | |
375 | internal Perl problems that would cause such a condition. | |
376 | ||
377 | This allows the programmer to look at the execution stack and variables to | |
378 | find out the cause of the exception. As the debugger is being invoked as | |
379 | the Perl interpreter is about to do a fatal exit, continuing the execution | |
380 | in debug mode is usally not practical. | |
381 | ||
382 | Starting Perl in the VMS debugger may change the program execution | |
383 | profile in a way that such problems are not reproduced. | |
384 | ||
385 | The C<kill> function can be used to test this functionality from within | |
386 | a program. | |
387 | ||
388 | In typical VMS style, only the first letter of the value of this logical | |
389 | name is actually checked in a case insensitive mode, and it is considered | |
390 | enabled if it is the value "T","1" or "E". | |
391 | ||
392 | This logical name must be defined before Perl is started. | |
393 | ||
4e592037 | 394 | =head1 Command line |
395 | ||
396 | =head2 I/O redirection and backgrounding | |
a0d0e21e LW |
397 | |
398 | Perl for VMS supports redirection of input and output on the | |
399 | command line, using a subset of Bourne shell syntax: | |
55497cff | 400 | |
773da73d | 401 | =over 4 |
07698885 RGS |
402 | |
403 | =item * | |
404 | ||
405 | C<E<lt>file> reads stdin from C<file>, | |
406 | ||
407 | =item * | |
408 | ||
409 | C<E<gt>file> writes stdout to C<file>, | |
410 | ||
411 | =item * | |
412 | ||
413 | C<E<gt>E<gt>file> appends stdout to C<file>, | |
414 | ||
415 | =item * | |
416 | ||
2fde0ff0 | 417 | C<2E<gt>file> writes stderr to C<file>, |
07698885 RGS |
418 | |
419 | =item * | |
420 | ||
2fde0ff0 RGS |
421 | C<2E<gt>E<gt>file> appends stderr to C<file>, and |
422 | ||
423 | =item * | |
424 | ||
425 | C<< 2>&1 >> redirects stderr to stdout. | |
07698885 RGS |
426 | |
427 | =back | |
a0d0e21e LW |
428 | |
429 | In addition, output may be piped to a subprocess, using the | |
430 | character '|'. Anything after this character on the command | |
431 | line is passed to a subprocess for execution; the subprocess | |
748a9306 | 432 | takes the output of Perl as its input. |
a0d0e21e LW |
433 | |
434 | Finally, if the command line ends with '&', the entire | |
435 | command is run in the background as an asynchronous | |
436 | subprocess. | |
437 | ||
4e592037 | 438 | =head2 Command line switches |
a0d0e21e | 439 | |
4e592037 | 440 | The following command line switches behave differently under |
441 | VMS than described in L<perlrun>. Note also that in order | |
442 | to pass uppercase switches to Perl, you need to enclose | |
443 | them in double-quotes on the command line, since the CRTL | |
444 | downcases all unquoted strings. | |
a0d0e21e | 445 | |
9296fdfa JM |
446 | On newer 64 bit versions of OpenVMS, a process setting now |
447 | controls if the quoting is needed to preserve the case of | |
448 | command line arguments. | |
449 | ||
55497cff | 450 | =over 4 |
451 | ||
edc7bc49 CB |
452 | =item -i |
453 | ||
454 | If the C<-i> switch is present but no extension for a backup | |
455 | copy is given, then inplace editing creates a new version of | |
456 | a file; the existing copy is not deleted. (Note that if | |
457 | an extension is given, an existing file is renamed to the backup | |
458 | file, as is the case under other operating systems, so it does | |
459 | not remain as a previous version under the original filename.) | |
460 | ||
4e592037 | 461 | =item -S |
a0d0e21e | 462 | |
376ae1f1 PP |
463 | If the C<"-S"> or C<-"S"> switch is present I<and> the script |
464 | name does not contain a directory, then Perl translates the | |
465 | logical name DCL$PATH as a searchlist, using each translation | |
466 | as a directory in which to look for the script. In addition, | |
4e592037 | 467 | if no file type is specified, Perl looks in each directory |
468 | for a file matching the name specified, with a blank type, | |
469 | a type of F<.pl>, and a type of F<.com>, in that order. | |
a0d0e21e | 470 | |
4e592037 | 471 | =item -u |
748a9306 | 472 | |
4e592037 | 473 | The C<-u> switch causes the VMS debugger to be invoked |
474 | after the Perl program is compiled, but before it has | |
475 | run. It does not create a core dump file. | |
748a9306 | 476 | |
55497cff | 477 | =back |
478 | ||
748a9306 | 479 | =head1 Perl functions |
a0d0e21e LW |
480 | |
481 | As of the time this document was last revised, the following | |
748a9306 | 482 | Perl functions were implemented in the VMS port of Perl |
a0d0e21e LW |
483 | (functions marked with * are discussed in more detail below): |
484 | ||
4fdae800 | 485 | file tests*, abs, alarm, atan, backticks*, binmode*, bless, |
a0d0e21e | 486 | caller, chdir, chmod, chown, chomp, chop, chr, |
c07a80fd | 487 | close, closedir, cos, crypt*, defined, delete, |
4e592037 | 488 | die, do, dump*, each, endpwent, eof, eval, exec*, |
41cbbefa | 489 | exists, exit, exp, fileno, getc, getlogin, getppid, |
4e592037 | 490 | getpwent*, getpwnam*, getpwuid*, glob, gmtime*, goto, |
491 | grep, hex, import, index, int, join, keys, kill*, | |
492 | last, lc, lcfirst, length, local, localtime, log, m//, | |
493 | map, mkdir, my, next, no, oct, open, opendir, ord, pack, | |
c07a80fd | 494 | pipe, pop, pos, print, printf, push, q//, qq//, qw//, |
4fdae800 | 495 | qx//*, quotemeta, rand, read, readdir, redo, ref, rename, |
a0d0e21e | 496 | require, reset, return, reverse, rewinddir, rindex, |
e518068a | 497 | rmdir, s///, scalar, seek, seekdir, select(internal), |
498 | select (system call)*, setpwent, shift, sin, sleep, | |
499 | sort, splice, split, sprintf, sqrt, srand, stat, | |
500 | study, substr, sysread, system*, syswrite, tell, | |
501 | telldir, tie, time, times*, tr///, uc, ucfirst, umask, | |
502 | undef, unlink*, unpack, untie, unshift, use, utime*, | |
503 | values, vec, wait, waitpid*, wantarray, warn, write, y/// | |
a0d0e21e LW |
504 | |
505 | The following functions were not implemented in the VMS port, | |
506 | and calling them produces a fatal error (usually) or | |
507 | undefined behavior (rarely, we hope): | |
508 | ||
41cbbefa CB |
509 | chroot, dbmclose, dbmopen, flock, fork*, |
510 | getpgrp, getpriority, getgrent, getgrgid, | |
c07a80fd | 511 | getgrnam, setgrent, endgrent, ioctl, link, lstat, |
512 | msgctl, msgget, msgsend, msgrcv, readlink, semctl, | |
513 | semget, semop, setpgrp, setpriority, shmctl, shmget, | |
bf99883d HM |
514 | shmread, shmwrite, socketpair, symlink, syscall |
515 | ||
35b2760a CB |
516 | The following functions are available on Perls compiled with Dec C |
517 | 5.2 or greater and running VMS 7.0 or greater: | |
bf99883d HM |
518 | |
519 | truncate | |
a0d0e21e | 520 | |
35b2760a CB |
521 | The following functions are available on Perls built on VMS 7.2 or |
522 | greater: | |
523 | ||
524 | fcntl (without locking) | |
525 | ||
a0d0e21e LW |
526 | The following functions may or may not be implemented, |
527 | depending on what type of socket support you've built into | |
748a9306 | 528 | your copy of Perl: |
4e592037 | 529 | |
a0d0e21e LW |
530 | accept, bind, connect, getpeername, |
531 | gethostbyname, getnetbyname, getprotobyname, | |
532 | getservbyname, gethostbyaddr, getnetbyaddr, | |
533 | getprotobynumber, getservbyport, gethostent, | |
534 | getnetent, getprotoent, getservent, sethostent, | |
535 | setnetent, setprotoent, setservent, endhostent, | |
536 | endnetent, endprotoent, endservent, getsockname, | |
c07a80fd | 537 | getsockopt, listen, recv, select(system call)*, |
538 | send, setsockopt, shutdown, socket | |
a0d0e21e | 539 | |
9296fdfa JM |
540 | The following function is available on Perls built on 64 bit OpenVMS 8.2 |
541 | with hard links enabled on an ODS-5 formatted build disk. If someone with | |
542 | an OpenVMS 7.3-1 system were to modify configure.com and test the results, | |
543 | this feature can be brought back to OpenVMS 7.3-1 and later. Hardlinks | |
544 | must be enabled on the build disk because if the build procedure sees | |
545 | this feature enabled, it uses it. | |
546 | ||
547 | link | |
548 | ||
549 | The following functions are available on Perls built on 64 bit OpenVMS | |
550 | 8.2 and can be implemented on OpenVMS 7.3-2 if someone were to modify | |
551 | configure.com and test the results. (While in the build, at the time | |
552 | of this writing, they have not been specifically tested.) | |
553 | ||
554 | getgrgid, getgrnam, getpwnam, getpwuid, | |
555 | setgrent, ttyname | |
556 | ||
557 | The following functions are available on Perls built on 64 bit OpenVMS 8.2 | |
558 | and later. (While in the build, at the time of this writing, they have | |
559 | not been specifically tested.) | |
560 | ||
561 | statvfs, socketpair | |
562 | ||
563 | The following functions are expected to soon be available on Perls built | |
564 | on 64 bit OpenVMS 8.2 or later with the RMS Symbolic link package. Use | |
565 | of symbolic links at this time effectively requires the | |
566 | DECC$POSIX_COMPLIANT_PATHNAMES to defined as 3, and operating in a | |
567 | DECC$FILENAME_UNIX_REPORT mode. | |
568 | ||
569 | lchown, link, lstat, readlink, symlink | |
52e64fc8 | 570 | |
55497cff | 571 | =over 4 |
a0d0e21e LW |
572 | |
573 | =item File tests | |
574 | ||
748a9306 LW |
575 | The tests C<-b>, C<-B>, C<-c>, C<-C>, C<-d>, C<-e>, C<-f>, |
576 | C<-o>, C<-M>, C<-s>, C<-S>, C<-t>, C<-T>, and C<-z> work as | |
577 | advertised. The return values for C<-r>, C<-w>, and C<-x> | |
578 | tell you whether you can actually access the file; this may | |
579 | not reflect the UIC-based file protections. Since real and | |
580 | effective UIC don't differ under VMS, C<-O>, C<-R>, C<-W>, | |
581 | and C<-X> are equivalent to C<-o>, C<-r>, C<-w>, and C<-x>. | |
582 | Similarly, several other tests, including C<-A>, C<-g>, C<-k>, | |
583 | C<-l>, C<-p>, and C<-u>, aren't particularly meaningful under | |
584 | VMS, and the values returned by these tests reflect whatever | |
585 | your CRTL C<stat()> routine does to the equivalent bits in the | |
586 | st_mode field. Finally, C<-d> returns true if passed a device | |
587 | specification without an explicit directory (e.g. C<DUA1:>), as | |
588 | well as if passed a directory. | |
589 | ||
fb38d079 | 590 | There are DECC feature logical names AND ODS-5 volume attributes that |
9296fdfa JM |
591 | also control what values are returned for the date fields. |
592 | ||
4e592037 | 593 | Note: Some sites have reported problems when using the file-access |
594 | tests (C<-r>, C<-w>, and C<-x>) on files accessed via DEC's DFS. | |
595 | Specifically, since DFS does not currently provide access to the | |
596 | extended file header of files on remote volumes, attempts to | |
597 | examine the ACL fail, and the file tests will return false, | |
598 | with C<$!> indicating that the file does not exist. You can | |
599 | use C<stat> on these files, since that checks UIC-based protection | |
600 | only, and then manually check the appropriate bits, as defined by | |
601 | your C compiler's F<stat.h>, in the mode value it returns, if you | |
602 | need an approximation of the file's protections. | |
603 | ||
4fdae800 | 604 | =item backticks |
605 | ||
606 | Backticks create a subprocess, and pass the enclosed string | |
607 | to it for execution as a DCL command. Since the subprocess is | |
608 | created directly via C<lib$spawn()>, any valid DCL command string | |
609 | may be specified. | |
610 | ||
748a9306 LW |
611 | =item binmode FILEHANDLE |
612 | ||
1c9f8daa | 613 | The C<binmode> operator will attempt to insure that no translation |
614 | of carriage control occurs on input from or output to this filehandle. | |
615 | Since this involves reopening the file and then restoring its | |
616 | file position indicator, if this function returns FALSE, the | |
617 | underlying filehandle may no longer point to an open file, or may | |
618 | point to a different position in the file than before C<binmode> | |
619 | was called. | |
620 | ||
621 | Note that C<binmode> is generally not necessary when using normal | |
622 | filehandles; it is provided so that you can control I/O to existing | |
623 | record-structured files when necessary. You can also use the | |
624 | C<vmsfopen> function in the VMS::Stdio extension to gain finer | |
625 | control of I/O to files and devices with different record structures. | |
a0d0e21e | 626 | |
c07a80fd | 627 | =item crypt PLAINTEXT, USER |
628 | ||
629 | The C<crypt> operator uses the C<sys$hash_password> system | |
630 | service to generate the hashed representation of PLAINTEXT. | |
631 | If USER is a valid username, the algorithm and salt values | |
632 | are taken from that user's UAF record. If it is not, then | |
633 | the preferred algorithm and a salt of 0 are used. The | |
634 | quadword encrypted value is returned as an 8-character string. | |
635 | ||
636 | The value returned by C<crypt> may be compared against | |
637 | the encrypted password from the UAF returned by the C<getpw*> | |
638 | functions, in order to authenticate users. If you're | |
639 | going to do this, remember that the encrypted password in | |
640 | the UAF was generated using uppercase username and | |
641 | password strings; you'll have to upcase the arguments to | |
642 | C<crypt> to insure that you'll get the proper value: | |
643 | ||
376ae1f1 PP |
644 | sub validate_passwd { |
645 | my($user,$passwd) = @_; | |
646 | my($pwdhash); | |
647 | if ( !($pwdhash = (getpwnam($user))[1]) || | |
648 | $pwdhash ne crypt("\U$passwd","\U$name") ) { | |
649 | intruder_alert($name); | |
650 | } | |
651 | return 1; | |
c07a80fd | 652 | } |
c07a80fd | 653 | |
6ac6a52b JM |
654 | |
655 | =item die | |
656 | ||
657 | C<die> will force the native VMS exit status to be an SS$_ABORT code | |
658 | if neither of the $! or $? status values are ones that would cause | |
659 | the native status to be interpreted as being what VMS classifies as | |
660 | SEVERE_ERROR severity for DCL error handling. | |
661 | ||
52e64fc8 JM |
662 | When the future POSIX_EXIT mode is active, C<die>, the native VMS exit |
663 | status value will have either one of the C<$!> or C<$?> or C<$^E> or | |
664 | the UNIX value 255 encoded into it in a way that the effective original | |
665 | value can be decoded by other programs written in C, including Perl | |
666 | and the GNV package. As per the normal non-VMS behavior of C<die> if | |
667 | either C<$!> or C<$?> are non-zero, one of those values will be | |
668 | encoded into a native VMS status value. If both of the UNIX status | |
669 | values are 0, and the C<$^E> value is set one of ERROR or SEVERE_ERROR | |
670 | severity, then the C<$^E> value will be used as the exit code as is. | |
671 | If none of the above apply, the UNIX value of 255 will be encoded into | |
672 | a native VMS exit status value. | |
673 | ||
674 | Please note a significant difference in the behavior of C<die> in | |
675 | the future POSIX_EXIT mode is that it does not force a VMS | |
676 | SEVERE_ERROR status on exit. The UNIX exit values of 2 through | |
677 | 255 will be encoded in VMS status values with severity levels of | |
678 | SUCCESS. The UNIX exit value of 1 will be encoded in a VMS status | |
679 | value with a severity level of ERROR. This is to be compatible with | |
680 | how the VMS C library encodes these values. | |
681 | ||
682 | The minimum severity level set by C<die> in a future POSIX_EXIT mode | |
683 | may be changed to be ERROR or higher before that mode becomes fully active | |
684 | depending on the results of testing and further review. If this is | |
685 | done, the behavior of c<DIE> in the future POSIX_EXIT will close enough | |
686 | to the default mode that most DCL shell scripts will probably not notice | |
687 | a difference. | |
688 | ||
689 | See C<$?> for a description of the encoding of the UNIX value to | |
690 | produce a native VMS status containing it. | |
691 | ||
6ac6a52b | 692 | |
4e592037 | 693 | =item dump |
694 | ||
695 | Rather than causing Perl to abort and dump core, the C<dump> | |
696 | operator invokes the VMS debugger. If you continue to | |
697 | execute the Perl program under the debugger, control will | |
698 | be transferred to the label specified as the argument to | |
699 | C<dump>, or, if no label was specified, back to the | |
700 | beginning of the program. All other state of the program | |
701 | (I<e.g.> values of variables, open file handles) are not | |
702 | affected by calling C<dump>. | |
703 | ||
748a9306 | 704 | =item exec LIST |
a0d0e21e | 705 | |
41cbbefa CB |
706 | A call to C<exec> will cause Perl to exit, and to invoke the command |
707 | given as an argument to C<exec> via C<lib$do_command>. If the | |
708 | argument begins with '@' or '$' (other than as part of a filespec), | |
709 | then it is executed as a DCL command. Otherwise, the first token on | |
710 | the command line is treated as the filespec of an image to run, and | |
711 | an attempt is made to invoke it (using F<.Exe> and the process | |
712 | defaults to expand the filespec) and pass the rest of C<exec>'s | |
713 | argument to it as parameters. If the token has no file type, and | |
714 | matches a file with null type, then an attempt is made to determine | |
715 | whether the file is an executable image which should be invoked | |
716 | using C<MCR> or a text file which should be passed to DCL as a | |
717 | command procedure. | |
a0d0e21e LW |
718 | |
719 | =item fork | |
720 | ||
41cbbefa CB |
721 | While in principle the C<fork> operator could be implemented via |
722 | (and with the same rather severe limitations as) the CRTL C<vfork()> | |
723 | routine, and while some internal support to do just that is in | |
724 | place, the implementation has never been completed, making C<fork> | |
725 | currently unavailable. A true kernel C<fork()> is expected in a | |
726 | future version of VMS, and the pseudo-fork based on interpreter | |
727 | threads may be available in a future version of Perl on VMS (see | |
728 | L<perlfork>). In the meantime, use C<system>, backticks, or piped | |
729 | filehandles to create subprocesses. | |
748a9306 LW |
730 | |
731 | =item getpwent | |
c07a80fd | 732 | |
748a9306 | 733 | =item getpwnam |
c07a80fd | 734 | |
748a9306 LW |
735 | =item getpwuid |
736 | ||
737 | These operators obtain the information described in L<perlfunc>, | |
738 | if you have the privileges necessary to retrieve the named user's | |
739 | UAF information via C<sys$getuai>. If not, then only the C<$name>, | |
740 | C<$uid>, and C<$gid> items are returned. The C<$dir> item contains | |
741 | the login directory in VMS syntax, while the C<$comment> item | |
742 | contains the login directory in Unix syntax. The C<$gcos> item | |
743 | contains the owner field from the UAF record. The C<$quota> | |
744 | item is not used. | |
a0d0e21e | 745 | |
e518068a | 746 | =item gmtime |
747 | ||
748 | The C<gmtime> operator will function properly if you have a | |
749 | working CRTL C<gmtime()> routine, or if the logical name | |
750 | SYS$TIMEZONE_DIFFERENTIAL is defined as the number of seconds | |
751 | which must be added to UTC to yield local time. (This logical | |
752 | name is defined automatically if you are running a version of | |
753 | VMS with built-in UTC support.) If neither of these cases is | |
754 | true, a warning message is printed, and C<undef> is returned. | |
755 | ||
756 | =item kill | |
757 | ||
39aca757 | 758 | In most cases, C<kill> is implemented via the CRTL's C<kill()> |
e518068a | 759 | function, so it will behave according to that function's |
760 | documentation. If you send a SIGKILL, however, the $DELPRC system | |
10a676f8 | 761 | service is called directly. This insures that the target |
e518068a | 762 | process is actually deleted, if at all possible. (The CRTL's C<kill()> |
763 | function is presently implemented via $FORCEX, which is ignored by | |
764 | supervisor-mode images like DCL.) | |
765 | ||
766 | Also, negative signal values don't do anything special under | |
767 | VMS; they're just converted to the corresponding positive value. | |
768 | ||
4fdae800 | 769 | =item qx// |
770 | ||
771 | See the entry on C<backticks> above. | |
772 | ||
e518068a | 773 | =item select (system call) |
774 | ||
775 | If Perl was not built with socket support, the system call | |
776 | version of C<select> is not available at all. If socket | |
777 | support is present, then the system call version of | |
778 | C<select> functions only for file descriptors attached | |
779 | to sockets. It will not provide information about regular | |
780 | files or pipes, since the CRTL C<select()> routine does not | |
781 | provide this functionality. | |
782 | ||
748a9306 | 783 | =item stat EXPR |
a0d0e21e | 784 | |
748a9306 LW |
785 | Since VMS keeps track of files according to a different scheme |
786 | than Unix, it's not really possible to represent the file's ID | |
787 | in the C<st_dev> and C<st_ino> fields of a C<struct stat>. Perl | |
788 | tries its best, though, and the values it uses are pretty unlikely | |
789 | to be the same for two different files. We can't guarantee this, | |
790 | though, so caveat scriptor. | |
791 | ||
792 | =item system LIST | |
793 | ||
794 | The C<system> operator creates a subprocess, and passes its | |
a0d0e21e | 795 | arguments to the subprocess for execution as a DCL command. |
e518068a | 796 | Since the subprocess is created directly via C<lib$spawn()>, any |
aa779de1 CB |
797 | valid DCL command string may be specified. If the string begins with |
798 | '@', it is treated as a DCL command unconditionally. Otherwise, if | |
799 | the first token contains a character used as a delimiter in file | |
800 | specification (e.g. C<:> or C<]>), an attempt is made to expand it | |
801 | using a default type of F<.Exe> and the process defaults, and if | |
802 | successful, the resulting file is invoked via C<MCR>. This allows you | |
803 | to invoke an image directly simply by passing the file specification | |
c93fa817 GS |
804 | to C<system>, a common Unixish idiom. If the token has no file type, |
805 | and matches a file with null type, then an attempt is made to | |
806 | determine whether the file is an executable image which should be | |
807 | invoked using C<MCR> or a text file which should be passed to DCL | |
808 | as a command procedure. | |
809 | ||
810 | If LIST consists of the empty string, C<system> spawns an | |
a2293a43 | 811 | interactive DCL subprocess, in the same fashion as typing |
c93fa817 GS |
812 | B<SPAWN> at the DCL prompt. |
813 | ||
748a9306 | 814 | Perl waits for the subprocess to complete before continuing |
4fdae800 | 815 | execution in the current process. As described in L<perlfunc>, |
816 | the return value of C<system> is a fake "status" which follows | |
c6966fea | 817 | POSIX semantics unless the pragma C<use vmsish 'status'> is in |
1b0c4952 CB |
818 | effect; see the description of C<$?> in this document for more |
819 | detail. | |
a0d0e21e | 820 | |
1c9f8daa | 821 | =item time |
822 | ||
823 | The value returned by C<time> is the offset in seconds from | |
824 | 01-JAN-1970 00:00:00 (just like the CRTL's times() routine), in order | |
825 | to make life easier for code coming in from the POSIX/Unix world. | |
826 | ||
a0d0e21e LW |
827 | =item times |
828 | ||
748a9306 LW |
829 | The array returned by the C<times> operator is divided up |
830 | according to the same rules the CRTL C<times()> routine. | |
a0d0e21e LW |
831 | Therefore, the "system time" elements will always be 0, since |
832 | there is no difference between "user time" and "system" time | |
39aca757 | 833 | under VMS, and the time accumulated by a subprocess may or may |
a0d0e21e | 834 | not appear separately in the "child time" field, depending on |
748a9306 LW |
835 | whether L<times> keeps track of subprocesses separately. Note |
836 | especially that the VAXCRTL (at least) keeps track only of | |
837 | subprocesses spawned using L<fork> and L<exec>; it will not | |
a2293a43 | 838 | accumulate the times of subprocesses spawned via pipes, L<system>, |
748a9306 LW |
839 | or backticks. |
840 | ||
16d20bd9 AD |
841 | =item unlink LIST |
842 | ||
843 | C<unlink> will delete the highest version of a file only; in | |
844 | order to delete all versions, you need to say | |
39aca757 | 845 | |
35b2760a | 846 | 1 while unlink LIST; |
39aca757 | 847 | |
16d20bd9 AD |
848 | You may need to make this change to scripts written for a |
849 | Unix system which expect that after a call to C<unlink>, | |
850 | no files with the names passed to C<unlink> will exist. | |
4633a7c4 LW |
851 | (Note: This can be changed at compile time; if you |
852 | C<use Config> and C<$Config{'d_unlink_all_versions'}> is | |
853 | C<define>, then C<unlink> will delete all versions of a | |
854 | file on the first call.) | |
16d20bd9 AD |
855 | |
856 | C<unlink> will delete a file if at all possible, even if it | |
857 | requires changing file protection (though it won't try to | |
858 | change the protection of the parent directory). You can tell | |
859 | whether you've got explicit delete access to a file by using the | |
860 | C<VMS::Filespec::candelete> operator. For instance, in order | |
861 | to delete only files to which you have delete access, you could | |
862 | say something like | |
4e592037 | 863 | |
16d20bd9 AD |
864 | sub safe_unlink { |
865 | my($file,$num); | |
866 | foreach $file (@_) { | |
867 | next unless VMS::Filespec::candelete($file); | |
868 | $num += unlink $file; | |
869 | } | |
870 | $num; | |
871 | } | |
4e592037 | 872 | |
873 | (or you could just use C<VMS::Stdio::remove>, if you've installed | |
874 | the VMS::Stdio extension distributed with Perl). If C<unlink> has to | |
875 | change the file protection to delete the file, and you interrupt it | |
876 | in midstream, the file may be left intact, but with a changed ACL | |
877 | allowing you delete access. | |
16d20bd9 | 878 | |
fb38d079 JM |
879 | This behavior of C<unlink> is to be compatible with POSIX behavior |
880 | and not traditional VMS behavior. | |
881 | ||
748a9306 LW |
882 | =item utime LIST |
883 | ||
941b3de1 CB |
884 | This operator changes only the modification time of the file (VMS |
885 | revision date) on ODS-2 volumes and ODS-5 volumes without access | |
886 | dates enabled. On ODS-5 volumes with access dates enabled, the | |
887 | true access time is modified. | |
748a9306 LW |
888 | |
889 | =item waitpid PID,FLAGS | |
890 | ||
39aca757 | 891 | If PID is a subprocess started by a piped C<open()> (see L<open>), |
376ae1f1 PP |
892 | C<waitpid> will wait for that subprocess, and return its final status |
893 | value in C<$?>. If PID is a subprocess created in some other way (e.g. | |
894 | SPAWNed before Perl was invoked), C<waitpid> will simply check once per | |
895 | second whether the process has completed, and return when it has. (If | |
896 | PID specifies a process that isn't a subprocess of the current process, | |
897 | and you invoked Perl with the C<-w> switch, a warning will be issued.) | |
35b2760a CB |
898 | |
899 | Returns PID on success, -1 on error. The FLAGS argument is ignored | |
900 | in all cases. | |
a0d0e21e | 901 | |
55497cff | 902 | =back |
903 | ||
a5f75d66 AD |
904 | =head1 Perl variables |
905 | ||
55497cff | 906 | The following VMS-specific information applies to the indicated |
907 | "special" Perl variables, in addition to the general information | |
a2293a43 | 908 | in L<perlvar>. Where there is a conflict, this information |
55497cff | 909 | takes precedence. |
910 | ||
911 | =over 4 | |
912 | ||
a5f75d66 AD |
913 | =item %ENV |
914 | ||
f675dbe5 CB |
915 | The operation of the C<%ENV> array depends on the translation |
916 | of the logical name F<PERL_ENV_TABLES>. If defined, it should | |
917 | be a search list, each element of which specifies a location | |
918 | for C<%ENV> elements. If you tell Perl to read or set the | |
919 | element C<$ENV{>I<name>C<}>, then Perl uses the translations of | |
920 | F<PERL_ENV_TABLES> as follows: | |
921 | ||
922 | =over 4 | |
923 | ||
924 | =item CRTL_ENV | |
925 | ||
926 | This string tells Perl to consult the CRTL's internal C<environ> | |
927 | array of key-value pairs, using I<name> as the key. In most cases, | |
928 | this contains only a few keys, but if Perl was invoked via the C | |
929 | C<exec[lv]e()> function, as is the case for CGI processing by some | |
930 | HTTP servers, then the C<environ> array may have been populated by | |
931 | the calling program. | |
932 | ||
933 | =item CLISYM_[LOCAL] | |
934 | ||
935 | A string beginning with C<CLISYM_>tells Perl to consult the CLI's | |
936 | symbol tables, using I<name> as the name of the symbol. When reading | |
937 | an element of C<%ENV>, the local symbol table is scanned first, followed | |
938 | by the global symbol table.. The characters following C<CLISYM_> are | |
939 | significant when an element of C<%ENV> is set or deleted: if the | |
940 | complete string is C<CLISYM_LOCAL>, the change is made in the local | |
39aca757 | 941 | symbol table; otherwise the global symbol table is changed. |
f675dbe5 CB |
942 | |
943 | =item Any other string | |
944 | ||
945 | If an element of F<PERL_ENV_TABLES> translates to any other string, | |
946 | that string is used as the name of a logical name table, which is | |
947 | consulted using I<name> as the logical name. The normal search | |
948 | order of access modes is used. | |
949 | ||
950 | =back | |
951 | ||
952 | F<PERL_ENV_TABLES> is translated once when Perl starts up; any changes | |
953 | you make while Perl is running do not affect the behavior of C<%ENV>. | |
954 | If F<PERL_ENV_TABLES> is not defined, then Perl defaults to consulting | |
955 | first the logical name tables specified by F<LNM$FILE_DEV>, and then | |
956 | the CRTL C<environ> array. | |
957 | ||
958 | In all operations on %ENV, the key string is treated as if it | |
959 | were entirely uppercase, regardless of the case actually | |
960 | specified in the Perl expression. | |
961 | ||
962 | When an element of C<%ENV> is read, the locations to which | |
963 | F<PERL_ENV_TABLES> points are checked in order, and the value | |
964 | obtained from the first successful lookup is returned. If the | |
965 | name of the C<%ENV> element contains a semi-colon, it and | |
966 | any characters after it are removed. These are ignored when | |
967 | the CRTL C<environ> array or a CLI symbol table is consulted. | |
968 | However, the name is looked up in a logical name table, the | |
969 | suffix after the semi-colon is treated as the translation index | |
970 | to be used for the lookup. This lets you look up successive values | |
971 | for search list logical names. For instance, if you say | |
a5f75d66 AD |
972 | |
973 | $ Define STORY once,upon,a,time,there,was | |
974 | $ perl -e "for ($i = 0; $i <= 6; $i++) " - | |
740ce14c | 975 | _$ -e "{ print $ENV{'story;'.$i},' '}" |
a5f75d66 | 976 | |
f675dbe5 CB |
977 | Perl will print C<ONCE UPON A TIME THERE WAS>, assuming, of course, |
978 | that F<PERL_ENV_TABLES> is set up so that the logical name C<story> | |
979 | is found, rather than a CLI symbol or CRTL C<environ> element with | |
980 | the same name. | |
981 | ||
3eeba6fb | 982 | When an element of C<%ENV> is set to a defined string, the |
f675dbe5 CB |
983 | corresponding definition is made in the location to which the |
984 | first translation of F<PERL_ENV_TABLES> points. If this causes a | |
985 | logical name to be created, it is defined in supervisor mode. | |
3eeba6fb CB |
986 | (The same is done if an existing logical name was defined in |
987 | executive or kernel mode; an existing user or supervisor mode | |
988 | logical name is reset to the new value.) If the value is an empty | |
989 | string, the logical name's translation is defined as a single NUL | |
990 | (ASCII 00) character, since a logical name cannot translate to a | |
991 | zero-length string. (This restriction does not apply to CLI symbols | |
992 | or CRTL C<environ> values; they are set to the empty string.) | |
f675dbe5 CB |
993 | An element of the CRTL C<environ> array can be set only if your |
994 | copy of Perl knows about the CRTL's C<setenv()> function. (This is | |
995 | present only in some versions of the DECCRTL; check C<$Config{d_setenv}> | |
996 | to see whether your copy of Perl was built with a CRTL that has this | |
997 | function.) | |
39aca757 | 998 | |
3eeba6fb | 999 | When an element of C<%ENV> is set to C<undef>, |
f675dbe5 CB |
1000 | the element is looked up as if it were being read, and if it is |
1001 | found, it is deleted. (An item "deleted" from the CRTL C<environ> | |
1002 | array is set to the empty string; this can only be done if your | |
1003 | copy of Perl knows about the CRTL C<setenv()> function.) Using | |
1004 | C<delete> to remove an element from C<%ENV> has a similar effect, | |
1005 | but after the element is deleted, another attempt is made to | |
1006 | look up the element, so an inner-mode logical name or a name in | |
1007 | another location will replace the logical name just deleted. | |
3eeba6fb CB |
1008 | In either case, only the first value found searching PERL_ENV_TABLES |
1009 | is altered. It is not possible at present to define a search list | |
1010 | logical name via %ENV. | |
f675dbe5 CB |
1011 | |
1012 | The element C<$ENV{DEFAULT}> is special: when read, it returns | |
1013 | Perl's current default device and directory, and when set, it | |
1014 | resets them, regardless of the definition of F<PERL_ENV_TABLES>. | |
1015 | It cannot be cleared or deleted; attempts to do so are silently | |
1016 | ignored. | |
b7b1864f CB |
1017 | |
1018 | Note that if you want to pass on any elements of the | |
1019 | C-local environ array to a subprocess which isn't | |
1020 | started by fork/exec, or isn't running a C program, you | |
1021 | can "promote" them to logical names in the current | |
1022 | process, which will then be inherited by all subprocesses, | |
1023 | by saying | |
1024 | ||
1025 | foreach my $key (qw[C-local keys you want promoted]) { | |
376ae1f1 PP |
1026 | my $temp = $ENV{$key}; # read from C-local array |
1027 | $ENV{$key} = $temp; # and define as logical name | |
b7b1864f CB |
1028 | } |
1029 | ||
1030 | (You can't just say C<$ENV{$key} = $ENV{$key}>, since the | |
1031 | Perl optimizer is smart enough to elide the expression.) | |
a5f75d66 | 1032 | |
6be8f7a6 JH |
1033 | Don't try to clear C<%ENV> by saying C<%ENV = ();>, it will throw |
1034 | a fatal error. This is equivalent to doing the following from DCL: | |
1035 | ||
1036 | DELETE/LOGICAL * | |
1037 | ||
1038 | You can imagine how bad things would be if, for example, the SYS$MANAGER | |
fb38d079 | 1039 | or SYS$SYSTEM logical names were deleted. |
4a0d0822 | 1040 | |
740ce14c | 1041 | At present, the first time you iterate over %ENV using |
edc7bc49 CB |
1042 | C<keys>, or C<values>, you will incur a time penalty as all |
1043 | logical names are read, in order to fully populate %ENV. | |
1044 | Subsequent iterations will not reread logical names, so they | |
1045 | won't be as slow, but they also won't reflect any changes | |
f675dbe5 CB |
1046 | to logical name tables caused by other programs. |
1047 | ||
fb38d079 JM |
1048 | You do need to be careful with the logical names representing |
1049 | process-permanent files, such as C<SYS$INPUT> and C<SYS$OUTPUT>. | |
1050 | The translations for these logical names are prepended with a | |
1051 | two-byte binary value (0x1B 0x00) that needs to be stripped off | |
1052 | if you wantto use it. (In previous versions of Perl it wasn't | |
1053 | possible to get the values of these logical names, as the null | |
1054 | byte acted as an end-of-string marker) | |
a5f75d66 | 1055 | |
a5f75d66 AD |
1056 | =item $! |
1057 | ||
1058 | The string value of C<$!> is that returned by the CRTL's | |
1059 | strerror() function, so it will include the VMS message for | |
1060 | VMS-specific errors. The numeric value of C<$!> is the | |
1061 | value of C<errno>, except if errno is EVMSERR, in which | |
1062 | case C<$!> contains the value of vaxc$errno. Setting C<$!> | |
4e592037 | 1063 | always sets errno to the value specified. If this value is |
1064 | EVMSERR, it also sets vaxc$errno to 4 (NONAME-F-NOMSG), so | |
1065 | that the string value of C<$!> won't reflect the VMS error | |
1066 | message from before C<$!> was set. | |
1067 | ||
1068 | =item $^E | |
1069 | ||
1070 | This variable provides direct access to VMS status values | |
1071 | in vaxc$errno, which are often more specific than the | |
1072 | generic Unix-style error messages in C<$!>. Its numeric value | |
1073 | is the value of vaxc$errno, and its string value is the | |
1074 | corresponding VMS message string, as retrieved by sys$getmsg(). | |
1075 | Setting C<$^E> sets vaxc$errno to the value specified. | |
1076 | ||
9296fdfa JM |
1077 | While Perl attempts to keep the vaxc$errno value to be current, if |
1078 | errno is not EVMSERR, it may not be from the current operation. | |
1079 | ||
4fdae800 | 1080 | =item $? |
1081 | ||
1082 | The "status value" returned in C<$?> is synthesized from the | |
1083 | actual exit status of the subprocess in a way that approximates | |
1084 | POSIX wait(5) semantics, in order to allow Perl programs to | |
1085 | portably test for successful completion of subprocesses. The | |
1086 | low order 8 bits of C<$?> are always 0 under VMS, since the | |
1087 | termination status of a process may or may not have been | |
9296fdfa JM |
1088 | generated by an exception. |
1089 | ||
1090 | The next 8 bits contain the termination status of the program. | |
1091 | ||
1092 | If the child process follows the convention of C programs | |
1093 | compiled with the _POSIX_EXIT macro set, the status value will | |
1094 | contain the actual value of 0 to 255 returned by that program | |
1095 | on a normal exit. | |
1096 | ||
52e64fc8 JM |
1097 | With the _POSIX_EXIT macro set, the UNIX exit value of zero is |
1098 | represented as a VMS native status of 1, and the UNIX values | |
1099 | from 2 to 255 are encoded by the equation: | |
1100 | ||
1101 | VMS_status = 0x35a000 + (unix_value * 8) + 1. | |
1102 | ||
1103 | And in the special case of unix value 1 the encoding is: | |
1104 | ||
1105 | VMS_status = 0x35a000 + 8 + 2 + 0x10000000. | |
9296fdfa JM |
1106 | |
1107 | For other termination statuses, the severity portion of the | |
52e64fc8 | 1108 | subprocess' exit status is used: if the severity was success or |
9296fdfa JM |
1109 | informational, these bits are all 0; if the severity was |
1110 | warning, they contain a value of 1; if the severity was | |
1111 | error or fatal error, they contain the actual severity bits, | |
52e64fc8 JM |
1112 | which turns out to be a value of 2 for error and 4 for severe_error. |
1113 | Fatal is another term for the severe_error status. | |
9bc98430 | 1114 | |
4fdae800 | 1115 | As a result, C<$?> will always be zero if the subprocess' exit |
1116 | status indicated successful completion, and non-zero if a | |
9296fdfa JM |
1117 | warning or error occurred or a program compliant with encoding |
1118 | _POSIX_EXIT values was run and set a status. | |
1119 | ||
52e64fc8 JM |
1120 | How can you tell the difference between a non-zero status that is |
1121 | the result of a VMS native error status or an encoded UNIX status? | |
1122 | You can not unless you look at the ${^CHILD_ERROR_NATIVE} value. | |
1123 | The ${^CHILD_ERROR_NATIVE} value returns the actual VMS status value | |
1124 | and check the severity bits. If the severity bits are equal to 1, | |
1125 | then if the numeric value for C<$?> is between 2 and 255 or 0, then | |
1126 | C<$?> accurately reflects a value passed back from a UNIX application. | |
1127 | If C<$?> is 1, and the severity bits indicate a VMS error (2), then | |
1128 | C<$?> is from a UNIX application exit value. | |
9296fdfa JM |
1129 | |
1130 | In practice, Perl scripts that call programs that return _POSIX_EXIT | |
52e64fc8 JM |
1131 | type status values will be expecting those values, and programs that |
1132 | call traditional VMS programs will either be expecting the previous | |
1133 | behavior or just checking for a non-zero status. | |
9296fdfa | 1134 | |
52e64fc8 | 1135 | And success is always the value 0 in all behaviors. |
9296fdfa | 1136 | |
fb38d079 | 1137 | When the actual VMS termination status of the child is an error, |
52e64fc8 JM |
1138 | internally the C<$!> value will be set to the closest UNIX errno |
1139 | value to that error so that Perl scripts that test for error | |
1140 | messages will see the expected UNIX style error message instead | |
1141 | of a VMS message. | |
fb38d079 | 1142 | |
9296fdfa JM |
1143 | Conversely, when setting C<$?> in an END block, an attempt is made |
1144 | to convert the POSIX value into a native status intelligible to | |
1145 | the operating system upon exiting Perl. What this boils down to | |
1146 | is that setting C<$?> to zero results in the generic success value | |
1147 | SS$_NORMAL, and setting C<$?> to a non-zero value results in the | |
1148 | generic failure status SS$_ABORT. See also L<perlport/exit>. | |
4fdae800 | 1149 | |
6ac6a52b | 1150 | With the future POSIX_EXIT mode set, setting C<$?> will cause the |
52e64fc8 JM |
1151 | new value to also be encoded into C<$^E> so that the either the |
1152 | original parent or child exit status values of 0 to 255 | |
1153 | can be automatically recovered by C programs expecting _POSIX_EXIT | |
1154 | behavior. If both a parent and a child exit value are non-zero, then it | |
1155 | will be assumed that this is actually a VMS native status value to | |
1156 | be passed through. The special value of 0xFFFF is almost a NOOP as | |
1157 | it will cause the current native VMS status in the C library to | |
1158 | become the current native Perl VMS status, and is handled this way | |
1159 | as consequence of it known to not be a valid native VMS status value. | |
1160 | It is recommend that only values in range of normal UNIX parent or | |
1161 | child status numbers, 0 to 255 are used. | |
6ac6a52b | 1162 | |
1b0c4952 | 1163 | The pragma C<use vmsish 'status'> makes C<$?> reflect the actual |
9bc98430 CB |
1164 | VMS exit status instead of the default emulation of POSIX status |
1165 | described above. This pragma also disables the conversion of | |
1166 | non-zero values to SS$_ABORT when setting C<$?> in an END | |
1167 | block (but zero will still be converted to SS$_NORMAL). | |
4fdae800 | 1168 | |
6ac6a52b | 1169 | Do not use the pragma C<use vmsish 'status'> with the future |
52e64fc8 JM |
1170 | POSIX_EXIT mode, as they are at times requesting conflicting |
1171 | actions and the consequence of ignoring this advice will be | |
1172 | undefined to allow future improvements in the POSIX exit handling. | |
6ac6a52b | 1173 | |
4e592037 | 1174 | =item $| |
1175 | ||
1176 | Setting C<$|> for an I/O stream causes data to be flushed | |
1177 | all the way to disk on each write (I<i.e.> not just to | |
1178 | the underlying RMS buffers for a file). In other words, | |
1179 | it's equivalent to calling fflush() and fsync() from C. | |
a5f75d66 | 1180 | |
55497cff | 1181 | =back |
1182 | ||
bf99883d HM |
1183 | =head1 Standard modules with VMS-specific differences |
1184 | ||
1185 | =head2 SDBM_File | |
1186 | ||
270c2ced | 1187 | SDBM_File works properly on VMS. It has, however, one minor |
4a4eefd0 GS |
1188 | difference. The database directory file created has a F<.sdbm_dir> |
1189 | extension rather than a F<.dir> extension. F<.dir> files are VMS filesystem | |
bf99883d HM |
1190 | directory files, and using them for other purposes could cause unacceptable |
1191 | problems. | |
1192 | ||
748a9306 | 1193 | =head1 Revision date |
a0d0e21e | 1194 | |
9296fdfa | 1195 | This document was last updated on 14-Oct-2005, for Perl 5, |
9bc98430 | 1196 | patchlevel 8. |
e518068a | 1197 | |
1198 | =head1 AUTHOR | |
1199 | ||
376ae1f1 PP |
1200 | Charles Bailey bailey@cor.newman.upenn.edu |
1201 | Craig Berry craigberry@mac.com | |
1202 | Dan Sugalski dan@sidhe.org | |
9296fdfa | 1203 | John Malmberg wb8tyw@qsl.net |