This is Info file perl.info, produced by Makeinfo version 1.68 from the input file bigperl.texi. settitle perl  File: perl.info, Node: perlvms, Next: perlwin32, Prev: perlos390, Up: Top VMS-specific documentation for Perl *********************************** NAME ==== perlvms - VMS-specific documentation for Perl DESCRIPTION =========== Gathered below are notes describing details of Perl 5's behavior on VMS. They are a supplement to the regular Perl 5 documentation, so we have focussed on the ways in which Perl 5 functions differently under VMS than it does under Unix, and on the interactions between Perl and the rest of the operating system. We haven't tried to duplicate complete descriptions of Perl features from the main Perl documentation, which can be found in the `[.pod]' subdirectory of the Perl distribution. We hope these notes will save you from confusion and lost sleep when writing Perl scripts on VMS. If you find we've missed something you think should appear here, please don't hesitate to drop a line to vmsperl@newman.upenn.edu. Installation ============ Directions for building and installing Perl 5 can be found in the file `README.vms' in the main source directory of the Perl distribution.. Organization of Perl Images =========================== Core Images ----------- During the installation process, three Perl images are produced. `Miniperl.Exe' is an executable image which contains all of the basic functionality of Perl, but cannot take advantage of Perl extensions. It is used to generate several files needed to build the complete Perl and various extensions. Once you've finished installing Perl, you can delete this image. Most of the complete Perl resides in the shareable image `PerlShr.Exe', which provides a core to which the Perl executable image and all Perl extensions are linked. You should place this image in `Sys$Share', or define the logical name `PerlShr' to translate to the full file specification of this image. It should be world readable. (Remember that if a user has execute only access to `PerlShr', VMS will treat it as if it were a privileged shareable image, and will therefore require all downstream shareable images to be INSTALLed, etc.) Finally, `Perl.Exe' is an executable image containing the main entry point for Perl, as well as some initialization code. It should be placed in a public directory, and made world executable. In order to run Perl with command line arguments, you should define a foreign command to invoke this image. Perl Extensions --------------- Perl extensions are packages which provide both XS and Perl code to add new functionality to perl. (XS is a meta-language which simplifies writing C code which interacts with Perl, see *Note Perlxs: perlxs, for more details.) The Perl code for an extension is treated like any other library module - it's made available in your script through the appropriate use or require statement, and usually defines a Perl package containing the extension. The portion of the extension provided by the XS code may be connected to the rest of Perl in either of two ways. In the static configuration, the object code for the extension is linked directly into `PerlShr.Exe', and is initialized whenever Perl is invoked. In the dynamic configuration, the extension's machine code is placed into a separate shareable image, which is mapped by Perl's DynaLoader when the extension is used or required in your script. This allows you to maintain the extension as a separate entity, at the cost of keeping track of the additional shareable image. Most extensions can be set up as either static or dynamic. The source code for an extension usually resides in its own directory. At least three files are generally provided: *Extshortname*`.xs' (where *Extshortname* is the portion of the extension's name following the last `::'), containing the XS code, *Extshortname*`.pm', the Perl library module for the extension, and Makefile.PL, a Perl script which uses the MakeMaker library modules supplied with Perl to generate a `Descrip.MMS' file for the extension. Installing static extensions ---------------------------- Since static extensions are incorporated directly into `PerlShr.Exe', you'll have to rebuild Perl to incorporate a new extension. You should edit the main `Descrip.MMS' or `Makefile' you use to build Perl, adding the extension's name to the ext macro, and the extension's object file to the `extobj' macro. You'll also need to build the extension's object file, either by adding dependencies to the main `Descrip.MMS', or using a separate `Descrip.MMS' for the extension. Then, rebuild `PerlShr.Exe' to incorporate the new code. Finally, you'll need to copy the extension's Perl library module to the `[.'*Extname*] subdirectory under one of the directories in `@INC', where *Extname* is the name of the extension, with all `::' replaced by . (e.g. the library module for extension Foo::Bar would be copied to a `[.Foo.Bar]' subdirectory). Installing dynamic extensions ----------------------------- In general, the distributed kit for a Perl extension includes a file named Makefile.PL, which is a Perl program which is used to create a `Descrip.MMS' file which can be used to build and install the files required by the extension. The kit should be unpacked into a directory tree not under the main Perl source directory, and the procedure for building the extension is simply $ perl Makefile.PL ! Create Descrip.MMS $ mmk ! Build necessary files $ mmk test ! Run test code, if supplied $ mmk install ! Install into public Perl tree *N.B.* 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, you shouldn't nest the source directory too deeply in your directory structure, lest you eccedd RMS' maximum of 8 levels of subdirectory in a filespec. (You can use rooted logical names to get another 8 levels of nesting, if you can't place the files near the top of the physical directory structure.) VMS support for this process in the current release of Perl is sufficient to handle most extensions. However, it does not yet recognize extra libraries required to build shareable images which are part of an extension, so these must be added to the linker options file for the extension by hand. For instance, if the `PGPLOT' extension to Perl requires the `PGPLOTSHR.EXE' shareable image in order to properly link the Perl extension, then the line `PGPLOTSHR/Share' must be added to the linker options file `PGPLOT.Opt' produced during the build process for the Perl extension. By default, the shareable image for an extension is placed `[.lib.site_perl.auto'*Arch*.*Extname*] directory of the installed Perl directory tree (where *Arch* is `VMS_VAX' or `VMS_AXP', and *Extname* is the name of the extension, with each `::' translated to .). (See the MakeMaker documentation for more details on installation options for extensions.) However, it can be manually placed in any of several locations: - the `[.Lib.Auto.'*Arch**$PVers**Extname*] subdirectory of one of the directories in `@INC' (where *PVers* is the version of Perl you're using, as supplied in $], with '.' converted to '_'), or - one of the directories in `@INC', or - a directory which the extensions Perl library module passes to the DynaLoader when asking it to map the shareable image, or - `Sys$Share' or `Sys$Library'. If the shareable image isn't in any of these places, you'll need to define a logical name *Extshortname*, where *Extshortname* is the portion of the extension's name after the last `::', which translates to the full file specification of the shareable image. File specifications =================== Syntax ------ We have tried to make Perl aware of both VMS-style and Unix- style file specifications wherever possible. You may use either style, or both, on the command line and in scripts, but you may not combine the two styles within a single fle specification. VMS Perl interprets Unix pathnames in much the same way as the CRTL (*e.g.* the first component of an absolute path is read as the device name for the VMS file specification). There are a set of functions provided in the `VMS::Filespec' 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.) We've tried to minimize the dependence of Perl library modules on Unix syntax, but you may find that some of these, as well as some scripts written for Unix systems, will require that you use Unix syntax, since they will assume that '/' is the directory separator, etc. If you find instances of this in the Perl distribution itself, please let us know, so we can try to work around them. Wildcard expansion ------------------ File specifications containing wildcards are allowed both on the command line and within Perl globs (e.g. >). If the wildcard filespec uses VMS syntax, the resultant filespecs will follow VMS syntax; if a Unix-style filespec is passed in, Unix-style filespecs will be returned. In both cases, VMS wildcard expansion is performed. (csh-style wildcard expansion is available if you use `File::Glob::glob'.) If the wildcard filespec contains a device or directory specification, then the resultant filespecs will also contain a device and directory; otherwise, device and directory information are removed. VMS-style resultant filespecs will contain a full device and directory, while Unix-style resultant filespecs will contain only as much of a directory path as was present in the input filespec. For example, if your default directory is Perl_Root:[000000], the expansion of `[.t]*.*' will yield filespecs like "perl_root:[t]base.dir", while the expansion of `t/*/*' will yield filespecs like "t/base.dir". (This is done to match 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. Pipes ----- Input and output pipes to Perl filehandles are supported; the "file name" is passed to lib$spawn() for asynchronous execution. You should be careful to close any pipes you have opened in a Perl script, lest you leave any "orphaned" subprocesses around when Perl exits. You may also use backticks to invoke a DCL subprocess, whose output is used as the return value of the expression. The string between the backticks is handled as if it were the argument to the system operator (see below). In this case, Perl will wait for the subprocess to complete before continuing. PERL5LIB and PERLLIB ==================== The PERL5LIB and PERLLIB logical names work as documented *Note Perl: perl,, except that the element separator is '|' instead of ':'. The directory specifications may use either VMS or Unix syntax. Command line ============ I/O redirection and backgrounding --------------------------------- Perl for VMS supports redirection of input and output on the command line, using a subset of Bourne shell syntax: reads stdin from F, >F writes stdout to F, >>F appends stdout to F, 2>F writes stderr to F, and 2>>F appends stderr to F. In addition, output may be piped to a subprocess, using the character '|'. Anything after this character on the command line is passed to a subprocess for execution; the subprocess takes the output of Perl as its input. Finally, if the command line ends with '&', the entire command is run in the background as an asynchronous subprocess. Command line switches --------------------- The following command line switches behave differently under VMS than described in *Note Perlrun: perlrun,. Note also that in order 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. -i If the -i switch is present but no extension for a backup copy is given, then inplace editing creates a new version of a file; the existing copy is not deleted. (Note that if an extension is given, an existing file is renamed to the backup file, as is the case under other operating systems, so it does not remain as a previous version under the original filename.) -S If the -S switch is present and the script name does not contain a directory, then Perl translates the logical name DCL$PATH as a searchlist, using each translation as a directory in which to look for the script. In addition, if no file type is specified, Perl looks in each directory for a file matching the name specified, with a blank type, a type of `.pl', and a type of `.com', in that order. -u The -u switch causes the VMS debugger to be invoked after the Perl program is compiled, but before it has run. It does not create a core dump file. Perl functions ============== As of the time this document was last revised, the following Perl functions were implemented in the VMS port of Perl (functions marked with * are discussed in more detail below): file tests*, abs, alarm, atan, backticks*, binmode*, bless, caller, chdir, chmod, chown, chomp, chop, chr, close, closedir, cos, crypt*, defined, delete, die, do, dump*, each, endpwent, eof, eval, exec*, exists, exit, exp, fileno, fork*, getc, getlogin, getpwent*, getpwnam*, getpwuid*, glob, gmtime*, goto, grep, hex, import, index, int, join, keys, kill*, last, lc, lcfirst, length, local, localtime, log, m//, map, mkdir, my, next, no, oct, open, opendir, ord, pack, pipe, pop, pos, print, printf, push, q//, qq//, qw//, qx//*, quotemeta, rand, read, readdir, redo, ref, rename, require, reset, return, reverse, rewinddir, rindex, rmdir, s///, scalar, seek, seekdir, select(internal), select (system call)*, setpwent, shift, sin, sleep, sort, splice, split, sprintf, sqrt, srand, stat, study, substr, sysread, system*, syswrite, tell, telldir, tie, time, times*, tr///, uc, ucfirst, umask, undef, unlink*, unpack, untie, unshift, use, utime*, values, vec, wait, waitpid*, wantarray, warn, write, y/// The following functions were not implemented in the VMS port, and calling them produces a fatal error (usually) or undefined behavior (rarely, we hope): chroot, dbmclose, dbmopen, fcntl, flock, getpgrp, getppid, getpriority, getgrent, getgrgid, getgrnam, setgrent, endgrent, ioctl, link, lstat, msgctl, msgget, msgsend, msgrcv, readlink, semctl, semget, semop, setpgrp, setpriority, shmctl, shmget, shmread, shmwrite, socketpair, symlink, syscall The following functions are available on Perls compiled with Dec C 5.2 or greater and running VMS 7.0 or greater truncate The following functions may or may not be implemented, depending on what type of socket support you've built into your copy of Perl: accept, bind, connect, getpeername, gethostbyname, getnetbyname, getprotobyname, getservbyname, gethostbyaddr, getnetbyaddr, getprotobynumber, getservbyport, gethostent, getnetent, getprotoent, getservent, sethostent, setnetent, setprotoent, setservent, endhostent, endnetent, endprotoent, endservent, getsockname, getsockopt, listen, recv, select(system call)*, send, setsockopt, shutdown, socket File tests The tests -b, -B, -c, -C, -d, -e, -f, -o, -M, -s, -S, -t, -T, and -z work as advertised. The return values for -r, -w, and -x tell you whether you can actually access the file; this may not reflect the UIC-based file protections. Since real and effective UIC don't differ under VMS, -O, `-R', -W, and -X are equivalent to -o, -r, -w, and -x. Similarly, several other tests, including -A, -g, -k, -l, -p, and -u, aren't particularly meaningful under VMS, and the values returned by these tests reflect whatever your CRTL stat() routine does to the equivalent bits in the st_mode field. Finally, -d returns true if passed a device specification without an explicit directory (e.g. `DUA1:'), as well as if passed a directory. Note: Some sites have reported problems when using the file-access tests (-r, -w, and -x) on files accessed via DEC's DFS. Specifically, since DFS does not currently provide access to the extended file header of files on remote volumes, attempts to examine the ACL fail, and the file tests will return false, with $! indicating that the file does not exist. You can use stat on these files, since that checks UIC-based protection only, and then manually check the appropriate bits, as defined by your C compiler's `stat.h', in the mode value it returns, if you need an approximation of the file's protections. backticks Backticks create a subprocess, and pass the enclosed string to it for execution as a DCL command. Since the subprocess is created directly via `lib$spawn()', any valid DCL command string may be specified. binmode FILEHANDLE The binmode operator will attempt to insure that no translation of carriage control occurs on input from or output to this filehandle. Since this involves reopening the file and then restoring its file position indicator, if this function returns FALSE, the underlying filehandle may no longer point to an open file, or may point to a different position in the file than before binmode was called. Note that binmode is generally not necessary when using normal filehandles; it is provided so that you can control I/O to existing record-structured files when necessary. You can also use the `vmsfopen' function in the VMS::Stdio extension to gain finer control of I/O to files and devices with different record structures. crypt PLAINTEXT, USER The crypt operator uses the `sys$hash_password' system service to generate the hashed representation of PLAINTEXT. If USER is a valid username, the algorithm and salt values are taken from that user's UAF record. If it is not, then the preferred algorithm and a salt of 0 are used. The quadword encrypted value is returned as an 8-character string. The value returned by crypt may be compared against the encrypted password from the UAF returned by the `getpw*' functions, in order to authenticate users. If you're going to do this, remember that the encrypted password in the UAF was generated using uppercase username and password strings; you'll have to upcase the arguments to crypt to insure that you'll get the proper value: sub validate_passwd { my($user,$passwd) = @_; my($pwdhash); if ( !($pwdhash = (getpwnam($user))[1]) || $pwdhash ne crypt("\U$passwd","\U$name") ) { intruder_alert($name); } return 1; } dump Rather than causing Perl to abort and dump core, the dump operator invokes the VMS debugger. If you continue to execute the Perl program under the debugger, control will be transferred to the label specified as the argument to dump, or, if no label was specified, back to the beginning of the program. All other state of the program (*e.g.* values of variables, open file handles) are not affected by calling dump. exec LIST The exec operator behaves in one of two different ways. If called after a call to fork, it will invoke the CRTL `execv()' routine, passing its arguments to the subprocess created by fork for execution. In this case, it is subject to all limitations that affect `execv()'. (In particular, this usually means that the command executed in the subprocess must be an image compiled from C source code, and that your options for passing file descriptors and signal handlers to the subprocess are limited.) If the call to exec does not follow a call to fork, it will cause Perl to exit, and to invoke the command given as an argument to exec via `lib$do_command'. If the argument begins with '@' or '$' (other than as part of a filespec), then it is executed as a DCL command. Otherwise, the first token on the command line is treated as the filespec of an image to run, and an attempt is made to invoke it (using `.Exe' and the process defaults to expand the filespec) and pass the rest of exec's argument to it as parameters. If the token has no file type, and matches a file with null type, then an attempt is made to determine whether the file is an executable image which should be invoked using `MCR' or a text file which should be passed to DCL as a command procedure. You can use exec in both ways within the same script, as long as you call fork and exec in pairs. Perl keeps track of how many times fork and exec have been called, and will call the CRTL `execv()' routine if there have previously been more calls to fork than to exec. fork The fork operator works in the same way as the CRTL `vfork()' routine, which is quite different under VMS than under Unix. Specifically, while fork returns 0 after it is called and the subprocess PID after exec is called, in both cases the thread of execution is within the parent process, so there is no opportunity to perform operations in the subprocess before calling exec. In general, the use of fork and exec to create subprocess is not recommended under VMS; wherever possible, use the system operator or piped filehandles instead. getpwent getpwnam getpwuid These operators obtain the information described in *Note Perlfunc: perlfunc,, if you have the privileges necessary to retrieve the named user's UAF information via `sys$getuai'. If not, then only the $name, `$uid', and `$gid' items are returned. The $dir item contains the login directory in VMS syntax, while the $comment item contains the login directory in Unix syntax. The `$gcos' item contains the owner field from the UAF record. The `$quota' item is not used. gmtime The gmtime operator will function properly if you have a working CRTL `gmtime()' routine, or if the logical name SYS$TIMEZONE_DIFFERENTIAL is defined as the number of seconds which must be added to UTC to yield local time. (This logical name is defined automatically if you are running a version of VMS with built-in UTC support.) If neither of these cases is true, a warning message is printed, and undef is returned. kill In most cases, kill kill is implemented via the CRTL's kill() function, so it will behave according to that function's documentation. If you send a SIGKILL, however, the $DELPRC system service is called directly. This insures that the target process is actually deleted, if at all possible. (The CRTL's kill() function is presently implemented via $FORCEX, which is ignored by supervisor-mode images like DCL.) Also, negative signal values don't do anything special under VMS; they're just converted to the corresponding positive value. qx// See the entry on backticks above. select (system call) If Perl was not built with socket support, the system call version of select is not available at all. If socket support is present, then the system call version of select functions only for file descriptors attached to sockets. It will not provide information about regular files or pipes, since the CRTL select() routine does not provide this functionality. stat EXPR Since VMS keeps track of files according to a different scheme than Unix, it's not really possible to represent the file's ID in the `st_dev' and `st_ino' fields of a `struct stat'. Perl tries its best, though, and the values it uses are pretty unlikely to be the same for two different files. We can't guarantee this, though, so caveat scriptor. system LIST The system operator creates a subprocess, and passes its arguments to the subprocess for execution as a DCL command. Since the subprocess is created directly via `lib$spawn()', any valid DCL command string may be specified. If the string begins with '@', it is treated as a DCL command unconditionally. Otherwise, if the first token contains a character used as a delimiter in file specification (e.g. : or ]), an attempt is made to expand it using a default type of `.Exe' and the process defaults, and if successful, the resulting file is invoked via `MCR'. This allows you to invoke an image directly simply by passing the file specification to system, a common Unixish idiom. If the token has no file type, and matches a file with null type, then an attempt is made to determine whether the file is an executable image which should be invoked using `MCR' or a text file which should be passed to DCL as a command procedure. If LIST consists of the empty string, system spawns an interactive DCL subprocess, in the same fashion as typiing *SPAWN* at the DCL prompt. Perl waits for the subprocess to complete before continuing execution in the current process. As described in *Note Perlfunc: perlfunc,, the return value of system is a fake "status" which follows POSIX semantics; see the description of $? in this document for more detail. The actual VMS exit status of the subprocess is available in $^S (as long as you haven't used another Perl function that resets $? and $^S in the meantime). time The value returned by time is the offset in seconds from 01-JAN-1970 00:00:00 (just like the CRTL's times() routine), in order to make life easier for code coming in from the POSIX/Unix world. times The array returned by the times operator is divided up according to the same rules the CRTL `times()' routine. Therefore, the "system time" elements will always be 0, since there is no difference between "user time" and "system" time under VMS, and the time accumulated by subprocess may or may not appear separately in the "child time" field, depending on whether `times' in this node keeps track of subprocesses separately. Note especially that the VAXCRTL (at least) keeps track only of subprocesses spawned using `fork' in this node and `exec' in this node; it will not accumulate the times of suprocesses spawned via pipes, `system' in this node, or backticks. unlink LIST unlink will delete the highest version of a file only; in order to delete all versions, you need to say 1 while (unlink LIST); You may need to make this change to scripts written for a Unix system which expect that after a call to unlink, no files with the names passed to unlink will exist. (Note: This can be changed at compile time; if you `use Config' and `$Config{'d_unlink_all_versions'}' is define, then unlink will delete all versions of a file on the first call.) unlink will delete a file if at all possible, even if it requires changing file protection (though it won't try to change the protection of the parent directory). You can tell whether you've got explicit delete access to a file by using the `VMS::Filespec::candelete' operator. For instance, in order to delete only files to which you have delete access, you could say something like sub safe_unlink { my($file,$num); foreach $file (@_) { next unless VMS::Filespec::candelete($file); $num += unlink $file; } $num; } (or you could just use `VMS::Stdio::remove', if you've installed the VMS::Stdio extension distributed with Perl). If unlink has to change the file protection to delete the file, and you interrupt it in midstream, the file may be left intact, but with a changed ACL allowing you delete access. utime LIST Since ODS-2, the VMS file structure for disk files, does not keep track of access times, this operator changes only the modification time of the file (VMS revision date). waitpid PID,FLAGS If PID is a subprocess started by a piped *Note Open: (pm.info)open,, waitpid will wait for that subprocess, and return its final status value. If PID is a subprocess created in some other way (e.g. SPAWNed before Perl was invoked), or is not a subprocess of the current process, waitpid will check once per second whether the process has completed, and when it has, will return 0. (If PID specifies a process that isn't a subprocess of the current process, and you invoked Perl with the -w switch, a warning will be issued.) The FLAGS argument is ignored in all cases. Perl variables ============== The following VMS-specific information applies to the indicated "special" Perl variables, in addition to the general information in *Note Perlvar: perlvar,. Where there is a conflict, this infrmation takes precedence. %ENV The operation of the %ENV array depends on the translation of the logical name `PERL_ENV_TABLES'. If defined, it should be a search list, each element of which specifies a location for %ENV elements. If you tell Perl to read or set the element `$ENV{'name`}', then Perl uses the translations of `PERL_ENV_TABLES' as follows: CRTL_ENV This string tells Perl to consult the CRTL's internal `environ' array of key-value pairs, using name as the key. In most cases, this contains only a few keys, but if Perl was invoked via the C `exec[lv]e()' function, as is the case for CGI processing by some HTTP servers, then the `environ' array may have been populated by the calling program. CLISYM_[LOCAL] A string beginning with `CLISYM_'tells Perl to consult the CLI's symbol tables, using name as the name of the symbol. When reading an element of %ENV, the local symbol table is scanned first, followed by the global symbol table.. The characters following `CLISYM_' are significant when an element of %ENV is set or deleted: if the complete string is `CLISYM_LOCAL', the change is made in the local symbol table, otherwise the global symbol table is changed. Any other string If an element of `PERL_ENV_TABLES' translates to any other string, that string is used as the name of a logical name table, which is consulted using name as the logical name. The normal search order of access modes is used. `PERL_ENV_TABLES' is translated once when Perl starts up; any changes you make while Perl is running do not affect the behavior of %ENV. If `PERL_ENV_TABLES' is not defined, then Perl defaults to consulting first the logical name tables specified by `LNM$FILE_DEV', and then the CRTL `environ' array. In all operations on %ENV, the key string is treated as if it were entirely uppercase, regardless of the case actually specified in the Perl expression. When an element of %ENV is read, the locations to which `PERL_ENV_TABLES' points are checked in order, and the value obtained from the first successful lookup is returned. If the name of the %ENV element contains a semi-colon, it and any characters after it are removed. These are ignored when the CRTL `environ' array or a CLI symbol table is consulted. However, the name is looked up in a logical name table, the suffix after the semi-colon is treated as the translation index to be used for the lookup. This lets you look up successive values for search list logical names. For instance, if you say $ Define STORY once,upon,a,time,there,was $ perl -e "for ($i = 0; $i <= 6; $i++) " - _$ -e "{ print $ENV{'story;'.$i},' '}" Perl will print `ONCE UPON A TIME THERE WAS', assuming, of course, that `PERL_ENV_TABLES' is set up so that the logical name `story' is found, rather than a CLI symbol or CRTL `environ' element with the same name. When an element of %ENV is set to a defined string, the corresponding definition is made in the location to which the first translation of `PERL_ENV_TABLES' points. If this causes a logical name to be created, it is defined in supervisor mode. (The same is done if an existing logical name was defined in executive or kernel mode; an existing user or supervisor mode logical name is reset to the new value.) If the value is an empty string, the logical name's translation is defined as a single NUL (ASCII 00) character, since a logical name cannot translate to a zero-length string. (This restriction does not apply to CLI symbols or CRTL `environ' values; they are set to the empty string.) An element of the CRTL `environ' array can be set only if your copy of Perl knows about the CRTL's `setenv()' function. (This is present only in some versions of the DECCRTL; check `$Config{d_setenv}' to see whether your copy of Perl was built with a CRTL that has this function.) When an element of %ENV is set to undef, the element is looked up as if it were being read, and if it is found, it is deleted. (An item "deleted" from the CRTL `environ' array is set to the empty string; this can only be done if your copy of Perl knows about the CRTL `setenv()' function.) Using delete to remove an element from %ENV has a similar effect, but after the element is deleted, another attempt is made to look up the element, so an inner-mode logical name or a name in another location will replace the logical name just deleted. In either case, only the first value found searching PERL_ENV_TABLES is altered. It is not possible at present to define a search list logical name via %ENV. The element `$ENV{DEFAULT}' is special: when read, it returns Perl's current default device and directory, and when set, it resets them, regardless of the definition of `PERL_ENV_TABLES'. It cannot be cleared or deleted; attempts to do so are silently ignored. Note that if you want to pass on any elements of the C-local environ array to a subprocess which isn't started by fork/exec, or isn't running a C program, you can "promote" them to logical names in the current process, which will then be inherited by all subprocesses, by saying foreach my $key (qw[C-local keys you want promoted]) { my $temp = $ENV{$key}; # read from C-local array $ENV{$key} = $temp; # and define as logical name } (You can't just say `$ENV{$key} = $ENV{$key}', since the Perl optimizer is smart enough to elide the expression.) At present, the first time you iterate over %ENV using keys, or values, you will incur a time penalty as all logical names are read, in order to fully populate %ENV. 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 `SYS$INPUT' and `SYS$OUTPUT'. 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) $! The string value of $! is that returned by the CRTL's strerror() function, so it will include the VMS message for VMS-specific errors. The numeric value of $! is the value of errno, except if errno is EVMSERR, in which case $! contains the value of vaxc$errno. Setting $! always sets errno to the value specified. If this value is EVMSERR, it also sets vaxc$errno to 4 (NONAME-F-NOMSG), so that the string value of $! won't reflect the VMS error message from before $! was set. $^E This variable provides direct access to VMS status values in vaxc$errno, which are often more specific than the generic Unix-style error messages in $!. Its numeric value is the value of vaxc$errno, and its string value is the corresponding VMS message string, as retrieved by sys$getmsg(). Setting $^E sets vaxc$errno to the value specified. $? The "status value" returned in $? is synthesized from the actual exit status of the subprocess in a way that approximates POSIX wait(5) semantics, in order to allow Perl programs to portably test for successful completion of subprocesses. The low order 8 bits of $? 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 severity portion of the subprocess' exit status: if the severity was success or informational, these bits are all 0; otherwise, they contain the severity value shifted left one bit. As a result, $? will always be zero if the subprocess' exit status indicated successful completion, and non-zero if a warning or error occurred. The actual VMS exit status may be found in $^S (q.v.). $^S Under VMS, this is the 32-bit VMS status value returned by the last subprocess to complete. Unlink $?, no manipulation is done to make this look like a POSIX wait(5) value, so it may be treated as a normal VMS status value. $| Setting $| for an I/O stream causes data to be flushed all the way to disk on each write (*i.e.* not just to the underlying RMS buffers for a file). In other words, it's equivalent to calling fflush() and fsync() from C. Standard modules with VMS-specific differences ============================================== SDBM_File --------- SDBM_File works properly on VMS. It has, however, one minor difference. The database directory file created has a `.sdbm_dir' extension rather than a `.dir' extension. `.dir' files are VMS filesystem directory files, and using them for other purposes could cause unacceptable problems. Revision date ============= This document was last updated on 26-Feb-2000, for Perl 5, patchlevel 6. AUTHOR ====== Charles Bailey Dan Sugalski  File: perl.info, Node: perlwin32, Next: Tk, Prev: perlvms, Up: Top Perl under Win32 **************** NAME ==== perlwin32 - Perl under Win32 SYNOPSIS ======== These are instructions for building Perl under Windows (9x, NT and 2000). DESCRIPTION =========== Before you start, you should glance through the README file found in the top-level directory where the Perl distribution was extracted. Make sure you read and understand the terms under which this software is being distributed. Also make sure you read `BUGS AND CAVEATS' in this node below for the known limitations of this port. The INSTALL file in the perl top-level has much information that is only relevant to people building Perl on Unix-like systems. In particular, you can safely ignore any information that talks about "Configure". You may also want to look at two other options for building a perl that will work on Windows NT: the README.cygwin and README.os2 files, which each give a different set of rules to build a Perl that will work on Win32 platforms. Those two methods will probably enable you to build a more Unix-compatible perl, but you will also need to download and use various other build-time and run-time support software described in those files. This set of instructions is meant to describe a so-called "native" port of Perl to Win32 platforms. The resulting Perl requires no additional software to run (other than what came with your operating system). Currently, this port is capable of using one of the following compilers: Borland C++ version 5.02 or later Microsoft Visual C++ version 4.2 or later Mingw32 with GCC version 2.95.2 or better The last of these is a high quality freeware compiler. Support for it is still experimental. (Older versions of GCC are known not to work.) This port currently supports MakeMaker (the set of modules that is used to build extensions to perl). Therefore, you should be able to build and install most extensions found in the CPAN sites. See `Usage Hints' in this node below for general hints about this. Setting Up ---------- Make You need a "make" program to build the sources. If you are using Visual C++ under Windows NT or 2000, nmake will work. All other builds need dmake. dmake is a freely available make that has very nice macro features and parallelability. A port of dmake for Windows is available from: http://www.cpan.org/authors/id/GSAR/dmake-4.1pl1-win32.zip (This is a fixed version of original dmake sources obtained from http://www.wticorp.com/dmake/. As of version 4.1PL1, the original sources did not build as shipped, and had various other problems. A patch is included in the above fixed version.) Fetch and install dmake somewhere on your path (follow the instructions in the README.NOW file). Command Shell Use the default "cmd" shell that comes with NT. Some versions of the popular 4DOS/NT shell have incompatibilities that may cause you trouble. If the build fails under that shell, try building again with the cmd shell. The nmake Makefile also has known incompatibilites with the "command.com" shell that comes with Windows 9x. You will need to use dmake and makefile.mk to build under Windows 9x. The surest way to build it is on Windows NT, using the cmd shell. Make sure the path to the build directory does not contain spaces. The build usually works in this circumstance, but some tests will fail. Borland C++ If you are using the Borland compiler, you will need dmake. (The make that Borland supplies is seriously crippled, and will not work for MakeMaker builds.) See L/"Make"> above. Microsoft Visual C++ The nmake that comes with Visual C++ will suffice for building. You will need to run the VCVARS32.BAT file usually found somewhere like C:\MSDEV4.2\BIN. This will set your build environment. You can also use dmake to build using Visual C++, provided: you set OSRELEASE to "microsft" (or whatever the directory name under which the Visual C dmake configuration lives) in your environment, and edit win32/config.vc to change "make=nmake" into "make=dmake". The latter step is only essential if you want to use dmake as your default make for building extensions using MakeMaker. Mingw32 with GCC GCC-2.95.2 binaries can be downloaded from: ftp://ftp.xraylith.wisc.edu/pub/khan/gnu-win32/mingw32/ The GCC-2.95.2 bundle comes with Mingw32 libraries and headers. Make sure you install the binaries that work with MSVCRT.DLL as indicated in the README for the GCC bundle. You may need to set up a few environment variables (usually run from a batch file). You also need dmake. See `' in this node above on how to get it. Building -------- * Make sure you are in the "win32" subdirectory under the perl toplevel. This directory contains a "Makefile" that will work with versions of nmake that come with Visual C++, and a dmake "makefile.mk" that will work for all supported compilers. The defaults in the dmake makefile are setup to build using the GCC compiler. * Edit the makefile.mk (or Makefile, if using nmake) and change the values of INST_DRV and INST_TOP. You can also enable various build flags. These are explained in the makefiles. You will have to make sure CCTYPE is set correctly, and CCHOME points to wherever you installed your compiler. The default value for CCHOME in the makefiles for Visual C++ may not be correct for some versions. Make sure the default exists and is valid. If you have either the source or a library that contains des_fcrypt(), enable the appropriate option in the makefile. des_fcrypt() is not bundled with the distribution due to US Government restrictions on the export of cryptographic software. Nevertheless, this routine is part of the "libdes" library (written by Eric Young) which is widely available worldwide, usually along with SSLeay (for example: "ftp://fractal.mta.ca/pub/crypto/SSLeay/DES/"). Set CRYPT_SRC to the name of the file that implements des_fcrypt(). Alternatively, if you have built a library that contains des_fcrypt(), you can set CRYPT_LIB to point to the library name. The location above contains many versions of the "libdes" library, all with slightly different implementations of des_fcrypt(). Older versions have a single, self-contained file (fcrypt.c) that implements crypt(), so they may be easier to use. A patch against the fcrypt.c found in libdes-3.06 is in des_fcrypt.patch. Perl will also build without des_fcrypt(), but the crypt() builtin will fail at run time. Be sure to read the instructions near the top of the makefiles carefully. * Type "dmake" (or "nmake" if you are using that make). This should build everything. Specifically, it will create perl.exe, perl56.dll at the perl toplevel, and various other extension dll's under the lib\auto directory. If the build fails for any reason, make sure you have done the previous steps correctly. Testing ------- Type "dmake test" (or "nmake test"). This will run most of the tests from the testsuite (many tests will be skipped). No tests should typically fail when running Windows NT 4.0. Under Windows 2000, test 22 in lib/open3.t is known to fail (cause still unknown). Many tests will fail under Windows 9x due to the inferior command shell. Some test failures may occur if you use a command shell other than the native "cmd.exe", or if you are building from a path that contains spaces. So don't do that. If you are running the tests from a emacs shell window, you may see failures in op/stat.t. Run "dmake test-notty" in that case. If you're using the Borland compiler, you may see a failure in op/taint.t arising from the inability to find the Borland Runtime DLLs on the system default path. You will need to copy the DLLs reported by the messages from where Borland chose to install it, into the Windows system directory (usually somewhere like C:\WINNT\SYSTEM32), and rerun the test. Please report any other failures as described under `BUGS AND CAVEATS' in this node. Installation ------------ Type "dmake install" (or "nmake install"). This will put the newly built perl and the libraries under whatever `INST_TOP' points to in the Makefile. It will also install the pod documentation under `$INST_TOP\$VERSION\lib\pod' and HTML versions of the same under `$INST_TOP\$VERSION\lib\pod\html'. To use the Perl you just installed, you will need to add two components to your PATH environment variable, `$INST_TOP\$VERSION\bin', and `$INST_TOP\$VERSION\bin\$ARCHNAME'. For example: set PATH c:\perl\5.6.0\bin;c:\perl\5.6.0\bin\MSWin32-x86;%PATH% If you opt to comment out INST_VER and INST_ARCH in the makefiles, the installation structure is much simpler. In that case, it will be sufficient to add a single entry to the path, for instance: set PATH c:\perl\bin;%PATH% Usage Hints ----------- Environment Variables The installation paths that you set during the build get compiled into perl, so you don't have to do anything additional to start using that perl (except add its location to your PATH variable). If you put extensions in unusual places, you can set PERL5LIB to a list of paths separated by semicolons where you want perl to look for libraries. Look for descriptions of other environment variables you can set in *Note Perlrun: perlrun,. You can also control the shell that perl uses to run system() and backtick commands via PERL5SHELL. See *Note Perlrun: perlrun,. Perl does not depend on the registry, but it can look up certain default values if you choose to put them there. Perl attempts to read entries from `HKEY_CURRENT_USER\Software\Perl' and `HKEY_LOCAL_MACHINE\Software\Perl'. Entries in the former override entries in the latter. One or more of the following entries (of type REG_SZ or REG_EXPAND_SZ) may be set: lib-$] version-specific standard library path to add to @INC lib standard library path to add to @INC sitelib-$] version-specific site library path to add to @INC sitelib site library path to add to @INC vendorlib-$] version-specific vendor library path to add to @INC vendorlib vendor library path to add to @INC PERL* fallback for all %ENV lookups that begin with "PERL" Note the $] in the above is not literal. Substitute whatever version of perl you want to honor that entry, e.g. `5.6.0'. Paths must be separated with semicolons, as usual on win32. File Globbing By default, perl handles file globbing using the File::Glob extension, which provides portable globbing. If you want perl to use globbing that emulates the quirks of DOS filename conventions, you might want to consider using File::DosGlob to override the internal glob() implementation. See *Note File/DosGlob: (pm.info)File/DosGlob, for details. Using perl from the command line If you are accustomed to using perl from various command-line shells found in UNIX environments, you will be less than pleased with what Windows offers by way of a command shell. The crucial thing to understand about the "cmd" shell (which is the default on Windows NT) is that it does not do any wildcard expansions of command-line arguments (so wildcards need not be quoted). It also provides only rudimentary quoting. The only (useful) quote character is the double quote ("). It can be used to protect spaces in arguments and other special characters. The Windows NT documentation has almost no description of how the quoting rules are implemented, but here are some general observations based on experiments: The shell breaks arguments at spaces and passes them to programs in argc/argv. Doublequotes can be used to prevent arguments with spaces in them from being split up. You can put a double quote in an argument by escaping it with a backslash and enclosing the whole argument within double quotes. The backslash and the pair of double quotes surrounding the argument will be stripped by the shell. The file redirection characters "<", ">", and "|" cannot be quoted by double quotes (there are probably more such). Single quotes will protect those three file redirection characters, but the single quotes don't get stripped by the shell (just to make this type of quoting completely useless). The caret "^" has also been observed to behave as a quoting character (and doesn't get stripped by the shell also). Here are some examples of usage of the "cmd" shell: This prints two doublequotes: perl -e "print '\"\"' " This does the same: perl -e "print \"\\\"\\\"\" " This prints "bar" and writes "foo" to the file "blurch": perl -e "print 'foo'; print STDERR 'bar'" > blurch This prints "foo" ("bar" disappears into nowhereland): perl -e "print 'foo'; print STDERR 'bar'" 2> nul This prints "bar" and writes "foo" into the file "blurch": perl -e "print 'foo'; print STDERR 'bar'" 1> blurch This pipes "foo" to the "less" pager and prints "bar" on the console: perl -e "print 'foo'; print STDERR 'bar'" | less This pipes "foo\nbar\n" to the less pager: perl -le "print 'foo'; print STDERR 'bar'" 2>&1 | less This pipes "foo" to the pager and writes "bar" in the file "blurch": perl -e "print 'foo'; print STDERR 'bar'" 2> blurch | less Discovering the usefulness of the "command.com" shell on Windows 9x is left as an exercise to the reader :) Building Extensions The Comprehensive Perl Archive Network (CPAN) offers a wealth of extensions, some of which require a C compiler to build. Look in http://www.cpan.org/ for more information on CPAN. Note that not all of the extensions available from CPAN may work in the Win32 environment; you should check the information at http://testers.cpan.org/ before investing too much effort into porting modules that don't readily build. Most extensions (whether they require a C compiler or not) can be built, tested and installed with the standard mantra: perl Makefile.PL $MAKE $MAKE test $MAKE install where $MAKE is whatever 'make' program you have configured perl to use. Use "perl -V:make" to find out what this is. Some extensions may not provide a testsuite (so "$MAKE test" may not do anything, or fail), but most serious ones do. It is important that you use a supported 'make' program, and ensure Config.pm knows about it. If you don't have nmake, you can either get dmake from the location mentioned earlier, or get an old version of nmake reportedly available from: ftp://ftp.microsoft.com/Softlib/MSLFILES/nmake15.exe Another option is to use the make written in Perl, available from CPAN: http://www.cpan.org/authors/id/NI-S/Make-0.03.tar.gz You may also use dmake. See `' in this node above on how to get it. Note that MakeMaker actually emits makefiles with different syntax depending on what 'make' it thinks you are using. Therefore, it is important that one of the following values appears in Config.pm: make='nmake' # MakeMaker emits nmake syntax make='dmake' # MakeMaker emits dmake syntax any other value # MakeMaker emits generic make syntax (e.g GNU make, or Perl make) If the value doesn't match the 'make' program you want to use, edit Config.pm to fix it. If a module implements XSUBs, you will need one of the supported C compilers. You must make sure you have set up the environment for the compiler for command-line compilation. If a module does not build for some reason, look carefully for why it failed, and report problems to the module author. If it looks like the extension building support is at fault, report that with full details of how the build failed using the perlbug utility. Command-line Wildcard Expansion The default command shells on DOS descendant operating systems (such as they are) usually do not expand wildcard arguments supplied to programs. They consider it the application's job to handle that. This is commonly achieved by linking the application (in our case, perl) with startup code that the C runtime libraries usually provide. However, doing that results in incompatible perl versions (since the behavior of the argv expansion code differs depending on the compiler, and it is even buggy on some compilers). Besides, it may be a source of frustration if you use such a perl binary with an alternate shell that *does* expand wildcards. Instead, the following solution works rather well. The nice things about it: 1) you can start using it right away 2) it is more powerful, because it will do the right thing with a pattern like */*/*.c 3) you can decide whether you do/don't want to use it 4) you can extend the method to add any customizations (or even entirely different kinds of wildcard expansion). C:\> copy con c:\perl\lib\Wild.pm # Wild.pm - emulate shell @ARGV expansion on shells that don't use File::DosGlob; @ARGV = map { my @g = File::DosGlob::glob($_) if /[*?]/; @g ? @g : $_; } @ARGV; 1; ^Z C:\> set PERL5OPT=-MWild C:\> perl -le "for (@ARGV) { print }" */*/perl*.c p4view/perl/perl.c p4view/perl/perlio.c p4view/perl/perly.c perl5.005/win32/perlglob.c perl5.005/win32/perllib.c perl5.005/win32/perlglob.c perl5.005/win32/perllib.c perl5.005/win32/perlglob.c perl5.005/win32/perllib.c Note there are two distinct steps there: 1) You'll have to create Wild.pm and put it in your perl lib directory. 2) You'll need to set the PERL5OPT environment variable. If you want argv expansion to be the default, just set PERL5OPT in your default startup environment. If you are using the Visual C compiler, you can get the C runtime's command line wildcard expansion built into perl binary. The resulting binary will always expand unquoted command lines, which may not be what you want if you use a shell that does that for you. The expansion done is also somewhat less powerful than the approach suggested above. Win32 Specific Extensions A number of extensions specific to the Win32 platform are available from CPAN. You may find that many of these extensions are meant to be used under the Activeware port of Perl, which used to be the only native port for the Win32 platform. Since the Activeware port does not have adequate support for Perl's extension building tools, these extensions typically do not support those tools either, and therefore cannot be built using the generic steps shown in the previous section. To ensure smooth transitioning of existing code that uses the ActiveState port, there is a bundle of Win32 extensions that contains all of the ActiveState extensions and most other Win32 extensions from CPAN in source form, along with many added bugfixes, and with MakeMaker support. This bundle is available at: http://www.cpan.org/authors/id/GSAR/libwin32-0.151.zip See the README in that distribution for building and installation instructions. Look for later versions that may be available at the same location. Running Perl Scripts Perl scripts on UNIX use the "#!" (a.k.a "shebang") line to indicate to the OS that it should execute the file using perl. Win32 has no comparable means to indicate arbitrary files are executables. Instead, all available methods to execute plain text files on Win32 rely on the file "extension". There are three methods to use this to execute perl scripts: 1. There is a facility called "file extension associations" that will work in Windows NT 4.0. This can be manipulated via the two commands "assoc" and "ftype" that come standard with Windows NT 4.0. Type "ftype /?" for a complete example of how to set this up for perl scripts (Say what? You thought Windows NT wasn't perl-ready? :). 2. Since file associations don't work everywhere, and there are reportedly bugs with file associations where it does work, the old method of wrapping the perl script to make it look like a regular batch file to the OS, may be used. The install process makes available the "pl2bat.bat" script which can be used to wrap perl scripts into batch files. For example: pl2bat foo.pl will create the file "FOO.BAT". Note "pl2bat" strips any .pl suffix and adds a .bat suffix to the generated file. If you use the 4DOS/NT or similar command shell, note that "pl2bat" uses the "%*" variable in the generated batch file to refer to all the command line arguments, so you may need to make sure that construct works in batch files. As of this writing, 4DOS/NT users will need a "ParameterChar = *" statement in their 4NT.INI file, or will need to execute "setdos /p*" in the 4DOS/NT startup file to enable this to work. 3. Using "pl2bat" has a few problems: the file name gets changed, so scripts that rely on $0 to find what they must do may not run properly; running "pl2bat" replicates the contents of the original script, and so this process can be maintenance intensive if the originals get updated often. A different approach that avoids both problems is possible. A script called "runperl.bat" is available that can be copied to any filename (along with the .bat suffix). For example, if you call it "foo.bat", it will run the file "foo" when it is executed. Since you can run batch files on Win32 platforms simply by typing the name (without the extension), this effectively runs the file "foo", when you type either "foo" or "foo.bat". With this method, "foo.bat" can even be in a different location than the file "foo", as long as "foo" is available somewhere on the PATH. If your scripts are on a filesystem that allows symbolic links, you can even avoid copying "runperl.bat". Here's a diversion: copy "runperl.bat" to "runperl", and type "runperl". Explain the observed behavior, or lack thereof. :) Hint: .gnidnats llits er'uoy fi ,"lrepnur" eteled :tniH Miscellaneous Things A full set of HTML documentation is installed, so you should be able to use it if you have a web browser installed on your system. perldoc is also a useful tool for browsing information contained in the documentation, especially in conjunction with a pager like less (recent versions of which have Win32 support). You may have to set the PAGER environment variable to use a specific pager. "perldoc -f foo" will print information about the perl operator "foo". If you find bugs in perl, you can run `perlbug' to create a bug report (you may have to send it manually if `perlbug' cannot find a mailer on your system). BUGS AND CAVEATS ================ Some of the built-in functions do not act exactly as documented in *Note Perlfunc: perlfunc,, and a few are not implemented at all. To avoid surprises, particularly if you have had prior exposure to Perl in other operating environments or if you intend to write code that will be portable to other environments, see *Note Perlport: perlport, for a reasonably definitive list of these differences. Not all extensions available from CPAN may build or work properly in the Win32 environment. See `' in this node. Most `socket()' related calls are supported, but they may not behave as on Unix platforms. See *Note Perlport: perlport, for the full list. Signal handling may not behave as on Unix platforms (where it doesn't exactly "behave", either :). For instance, calling `die()' or exit() from signal handlers will cause an exception, since most implementations of `signal()' on Win32 are severely crippled. Thus, signals may work only for simple things like setting a flag variable in the handler. Using signals under this port should currently be considered unsupported. Please send detailed descriptions of any problems and solutions that you may find to <`perlbug@perl.com'>, along with the output produced by `perl -V'. AUTHORS ======= Gary Ng <71564.1743@CompuServe.COM> Gurusamy Sarathy Nick Ing-Simmons This document is maintained by Gurusamy Sarathy. SEE ALSO ======== *Note Perl: perl, HISTORY ======= This port was originally contributed by Gary Ng around 5.003_24, and borrowed from the Hip Communications port that was available at the time. Various people have made numerous and sundry hacks since then. Borland support was added in 5.004_01 (Gurusamy Sarathy). GCC/mingw32 support was added in 5.005 (Nick Ing-Simmons). Support for PERL_OBJECT was added in 5.005 (ActiveState Tool Corp). Support for fork() emulation was added in 5.6 (ActiveState Tool Corp). Win9x support was added in 5.6 (Benjamin Stuhl). Last updated: 22 March 2000