Information on Utilities release, with additional capabilities and with improved error diagnostics. OpenVMS Alpha V7.3 and later include a version of SYS$DQDRIVER with the necessary IO$_DIAGNOSE support. __________________________________________________________ 7.2 How do I access a Microsoft Windows floppy disk from OpenVMS? The HP Advanced Server (formerly known as PATHWORKS) for OpenVMS product includes an unsupported and undocumented utility called PCDISK, and this tool can read and write various Microsoft MS-DOS and Microsoft Windows FAT-format diskettes. ProGIS in Germany sells a product called VMove which supports DOS files on many different device types. For more information, send mail to info@progis.de. Engineering Software has a product called VAKSAT which will read, write, and erase files on MS-DOS FAT diskettes. Available for both VAX and Alpha. Contact ed@cityscape.co.uk for more information. MadGoat PC Exchange (PCX) is a utility for copying files to and from MS-DOS and Microsoft Windows (FAT) format diskettes under OpenVMS, using an RX23 (3.5"), RX26 (3.5"), or RX33 (5.25") diskette drive. For 3.5" diskettes, high-density disks can be read or written; double-density disks are read-only. Only high-density disks are supported on the RX33. o http://www.madgoat.com/ The Freeware package WINFX is available on Freeware V6.0, and can read the FAT volume structure. o http://www.hp.com/go/openvms/freeware/ 7-2 Information on Utilities __________________________________________________________ 7.3 How do I play sound files on an AlphaStation? DECsound doesn't work. The new AlphaStation systems use a different sound board (Microsoft Sound System) than the earlier DEC 3000 series systems, and DECsound, as supplied by DECwindows Motif, doesn't support this board. HP offers an optional product, Multimedia Services for OpenVMS: o http://www.compaq.com/info/spd/ OpenVMS typically uses SPD 25.01.xx and/or SPD 41.87.xx. which provides a replacement DECsound for this card as well as many other features (an AVI and MPEG player, video capture support, etc.) Ensoniq sound support is also available. __________________________________________________________ 7.4 Why is DECmigrate not working with Fortran? %OTS-F-INDATCOR internal data corrupted in Run- time Library This error can arise with Fortran programs if you are running a recent version of OpenVMS Alpha, and are using DECmigrate to translate Fortran applications. The DECmigrate Run-Time Library attempts to support mixed translated-native I/O to the same unit by sharing the native Fortran RTL's internal data structures, and in OpenVMS 7.2 these structures changed and the translated RTL was not updated accordingly. You can copy DEC$FORRTL.EXE from OpenVMS 7.1, copying it to some spare directory, and then defining the logical name DEC$FORRTL to point to it before running your translated application. Or rebuilding the application to use the available native Fortran compiler. Or you can apply the current Fortran RTL kit, which has a fix for this. See Section 13.11. 7-3 Information on Utilities __________________________________________________________ 7.5 How do I read IBM EBCDIC tapes on OpenVMS? Most (all?) IBM EBCDIC-based systems can read and write ANSI-labeled ASCII magtapes. Fixed-length records (MOUNT /FOREIGN /BLOCKSIZE=512 /RECORDSIZE=512, for one-block records) and the DCL COPY command can be used to transfer fixed-record-size text files out onto tape media, or to read from fixed-record tape media. Please consult the IBM documentation for the details and command syntax needed when reading and writing ANSI media using IBM JCL or other applicable IBM command language. There exists various freeware around (TAPECOPY, ETAPE, TCOPY, MTEXCH) that can read and write EBCDIC tapes. Visit the Encompasserve (DECUS) website software archives search engine (via http://www.decus.org/), and search for "EBCDIC" for details. OpenVMS does not include an integrated tool for EBCDIC tape processing, but does provide a character conversion API useful within application programs. One source for ETAPE is: o http://www.ualr.edu/ftp/vms/ETAPE_SRC/ The OpenVMS Freeware V5.0 distribution included this ETAPE tool, as well. __________________________________________________________ 7.6 How can I patch an OpenVMS Alpha image? Using the OpenVMS Freeware tool ZAP: o http://www.hp.com/go/openvms/freeware/, look for the Freeware V5.0 directory /rms_tools/. tell ZAP to read a block (bucket) of information based on the virtual block number (VBN), using X for hexadecimal. Dump yourself into the OpenVMS debugger with R2 pointing into the buffer, EXAMINE/INSTRUCTION as needed, alter the buffer as required, GO to get out of the debugger and back into ZAP, and use the ZAP W command to write the updated block. 7-4 _______________________________________________________ 8 DCL Details __________________________________________________________ 8.1 How do I run a program with arguments? The RUN command does not accept arguments. To pass arguments to a program, you must use what is called a "foreign command". For example: $ unzip :== $disk:[dir]unzip.exe $ unzip -? The leading $ in the equivilence name for the symbol definition is what makes the DCL symbol a foreign command. If the device and directory are omitted, SYS$SYSTEM: is assumed. Under OpenVMS V6.2 and later, DCL supports automatic foreign command definition via the logical name DCL$PATH:. An example of a definition of this logical name is: $ DEFINE DCL$PATH SYS$DISK:[],ddcu:[mytooldir],SYS$SYSTEM: DCL will first look for a command in the DCL command table, and if no match is found and if DCL$PATH is defined, it will then look for command procedures and executable images with filenames matching the command specified, in the directories specified via DCL$PATH. The first match found is invoked, and under OpenVMS, the DCL$PATH support will cause a command procedure to be activated in preference to an executable image. For more information on foreign commands or on automatic foreign command support, see the OpenVMS User's Manual. See also Section 10.3. If you want to create a detached process that takes arguments from a command line, it must be run under the control of a command line interpreter (CLI) (typically DCL). This is done by placing the command line in a 8-1 DCL Details file, specifying SYS$SYSTEM:LOGINOUT.EXE as the image to run and the command file as the input. For example: $ OPEN/WRITE CMD TEMP_INPUT.COM $ WRITE CMD "$ MYCOMMAND arguments" $ CLOSE CMD $ RUN/DETACHED SYS$SYSTEM:LOGINOUT /INPUT=TEMP_INPUT.COM Various OpenVMS library calls (such as lib$spawn(), cli$dcl_parse(), and the C library system() call) require access to a command line interpreter such as DCL to perform requested actions, and will not operate if a CLI is not available. When a CLI is not available, these calls typically return the error status SS$_NOCLI. And as mentioned above, invoke the image LOGINOUT to cause a CLI (such as DCL) to be mapped into and made available in the context of the target process. For examples of how TCP/IP Services sets up its foreign commands (which includes tools such as uuencode and uudecode), please see the DCL command procedure SYS$STARTUP:TCPIP$DEFINE_COMMANDS.COM. Also see Section 8.10. __________________________________________________________ 8.2 How can I clear the screen in DCL? The simplest way is the TYPE/PAGE NLA0: command. You can set up a symbol to clear the screen in your LOGIN.COM: $ CLS :== TYPE/PAGE NLA0: __________________________________________________________ 8.3 Using REPLY/LOG from DCL? Disabling Console OPCOMs? Your terminal must be enabled as an operator terminal before the REPLY/LOG command can be used, but a DCL procedure (batch command file, system startup, etc) does not have an associated terminal. To make this work, use the following sequence to enable the OPA0: console as the operator terminal, then the REPLY/LOG command will be accepted: 8-2 DCL Details $ DEFINE/USER SYS$COMMAND _OPA0: $ REPLY/LOG $ DEFINE/USER SYS$COMMAND _OPA0: $ REPLY/ENABLE To disable the system console terminal (OPA0:) as an operator terminal, use the following command: $ DEFINE/USER SYS$COMMAND _OPA0: $ REPLY/DISABLE Also see SYLOGICALS.COM (and SYLOGICALS.TEMPLATE) for information on configuring the behaviour of OPCOM, including the (default) use of the system console (OPA0:) as an operator terminial and the specific contents and behaviour of the system operator log file OPERATOR.LOG. __________________________________________________________ 8.4 How do I generate a random number in DCL? Here is a random number generator, just do a GOSUB RAND and the global symbol RANDOM will contain a randomly generated number. You can feed the generator a ceiling value (__CEIL) or a new seed (__SEED). 8-3 DCL Details $! RAND - returns a positive random number ("RANDOM") between 0 and $! __CEIL - 1. $! sharris-at-sdsdmvax.fb3.noaa.gov $ RAND: $ $ IF F$TYPE(__SEED) .EQS. "" $ THEN $ ! seed the random number generator, ... $ __NOW = F$CVTIME() $ __HOUR = 'F$EXTRACT(11,2,__NOW)' $ __MINUTE = 'F$EXTRACT(14,2,__NOW)' $ __SECOND = 'F$EXTRACT(17,2,__NOW)' $ __TICK = 'F$EXTRACT(20,2,__NOW)' $ $ __SEED == __TICK + (100 * __SECOND) + (6000 * __MINUTE) + - (360000 * __HOUR) $ ! the generator tends to do better with a large, odd seed, ... $ __SEED == (__SEED .OR. 1) $ ! clean up, ... $ DELETEX/SYMBOL __NOW $ DELETEX/SYMBOL __HOUR $ DELETEX/SYMBOL __MINUTE $ DELETEX/SYMBOL __SECOND $ DELETEX/SYMBOL __TICK $ ENDIF $ $ IF F$TYPE(__CEIL) .EQS. "" THEN __CEIL = %X3FFFFFFF $ $ __SEED == __SEED * 69069 + 1 $ $ RANDOM == (__SEED.AND.%X3FFFFFFF)/(%X40000000/__CEIL) $ $ RETURN __________________________________________________________ 8.5 What does the MCR command do? The MCR is an artifact of RSX compatibility mode, the operating system from which OpenVMS is descended. MCR is the Monitor Console Routine, and the command is intended to activate RSX compatibility mode utilities. When used on OpenVMS, the command is most commonly used to run the specified image and-because the tool 8-4 DCL Details detects the image is not a compatibility-mode image- it acts as a form of RUN command with the default file specification of SYS$SYSTEM:.EXE. MCR passes any (optional) command line arguments in a fashion similar to a foreign command. In other words: $ MCR FOO BAR is equivalent to: $ FOO :== $FOO $ FOO BAR MCR is not documented. Use of a foreign command or the DCL$PATH mechanism is preferred. For details on this, see Section 8.1. __________________________________________________________ 8.6 How do I change the OpenVMS system prompt? You can use the SET PROMPT command for this purpose. SET PROMPT sets the DCL prompt to the specified string. When you want to display variable information, you will need to establish a tie-in that provides the information to the SET PROMPT command as required. If you wish to display the default directory for instance, you will have to establish a tie between the SET DEFAULT command and the SET PROMPT commands, as there is no direct way to get the default directory as the DCL prompt. You can easily acquire or create a set of DCL command procedures that perform the SET DEFAULT and SET PROMPT for you. These DCL command procedures often use a command such as: $ set prompt='f$environment("default")' More advanced users could implement a system service or other intercept, and use these tools to intercept the directory change and reset the prompt accordingly. (This approach likely involves some kernel-mode programming, and requires write access to various undocumented OpenVMS data structures.) There are related tools available from various sources, including the following web sites: o ftp://ftp.hhs.dk/pub/vms/setpmt/ 8-5 DCL Details o ftp://ftp.tmesis.com/sys_service_hook.src o James F. Duff has also made available a Macro32 tool known as TIME_PROMPT, a tool that sets the prompt to the current system time. o Many folks have contributed DCL procedures to perform this task. Visit the newsgroup archives for information and examples. __________________________________________________________ 8.7 Can I do DECnet task-to-task communication with DCL? Yes, you can do this with DCL. The OpenVMS DECnet documentation shows various simple examples using the task object and the TYPE command to trigger the execution of a DCL command procedure on a remote node. An example DCL command procedure that is rather more advanced than using the TYPE command as a trigger is included in the Ask The Wizard area: o http://www.hp.com/go/openvms/wizard/ For additional information on the OpenVMS Ask The Wizard (ATW) area and for a pointer to the available ATW Wizard.zip archive, please see Section 3.9. DCL does not include support asynchronous I/O, thus a predetermined protocol or a predetermined "turn-around" command sequence must be implemented in order to avoid protocol deadlocks-cases where both tasks are trying to write or both tasks are trying to read. The task that is writing messages to the network must write (or write and read) a predetermined sequence of messages, or it must write a message that tells the reader that it can now start writing messages. (This is the essence of a basic half-duplex network protocol scheme.) __________________________________________________________ 8.8 How can I get the width setting of a terminal? $ width = f$getdvi(terminal,"DEVBUFSIZ") 8-6 DCL Details __________________________________________________________ 8.9 How can I substitute symbols in a PIPE? Use DCL ampersand substitution, and not apostrophe substitution. $ pipe show system | search sys$input opcom | (read sys$input pid ; pid=f$element(0," ",pid) ; define/system opcom_pid &pid) $ show log opcom_pid "OPCOM_PID" = "0000020B" (LNM$SYSTEM_TABLE) __________________________________________________________ 8.10 Use of RUN/DETACH, LOGINOUT, and logical names? With a command to create a detached process such as: $ RUN/DETACHED SYS$SYSTEM:LOGINOUT /INPUT=TEMP_INPUT.COM If you are trying to use a logical name as the /INPUT, /OUTPUT or /ERROR on a RUN/DETACH command, then you must translate the logical name specifications to physical references before passing them, or the definitions must reside in a logical name table that is visible to the newly-created process. Also note that LOGINOUT only creates the SYS$LOGIN, SYS$LOGIN_DEVICE, and SYS$SCRATCH logical names if it is processing a login that is based on the contents of a SYSUAF record-without access to the associated SYSUAF record, this information is not available to LOGINOUT. (If you want to see these particular logical names created, then please specify the /AUTHORIZE qualifier on the RUN/DETACHED command.) If you do not specify LOGINOUT as the image, then there is no easy way to get these logical names. Also, any logical names that are used in the target image file specification must also be in a logical name table accessible (by default) by the newly-created detached process. Shared tables include the group (if the process is in the same UIC group) and the system table. (If the target process is to be in another UIC group, a suitablly privileged user or application can create the necessary logical name(s) directly in the other group logical name table.) 8-7 DCL Details When in doubt, create a short DCL command file as input, and use a SHOW LOGICAL and similar commands to examine the context. (And use physical device and directory references on the RUN/DETACH of the LOGINOUT image, when specifying this command file as /INPUT.) Also remember to check both security auditing and system accounting when troubleshooting problems with the RUN/DETACH. Also see Section 8.1. __________________________________________________________ 8.11 How to use escape and control characters in DCL? To write a message and then the bell character, use: $ bell[0,7] = 7 $ write sys$output "Hello''bell'" To write blinking text, use: $ esc[0,7] = 27 $ text = "Blinking Text" $ write sys$output "''esc'[5m''text'''esc'[m" Also see sections Section 11.7, Section 12.1. 8-8 _______________________________________________________ 9 Files __________________________________________________________ 9.1 How can I undelete a file? OpenVMS doesn't have an "undelete" function. However, if you are quick to write-protect the disk or if you can guarantee that no new files get created or existing files extended, your data is still on the disk and it may be possible to retrieve it. The FLORIAN tool available from various websites can potentially recover the file, see question Section 13.1 for pointers. Other alternatives here include the DFU tool, available on the OpenVMS Freeware CD-ROM distribution. If you are setting up a user environment for yourself or for others, it is quite easy to use DCL to intercept the DELETE command, using a symbol: $ DEL*ETE :== @SYS$LOGIN:MYDELETE.COM The DELETE symbol will cause the procedure to be invoked whenever the user enters the DELETE command, and it can copy the file(s) to a "trashcan" subdirectory before issuing a "real" DELETE on the files. Other procedures can retrieve the file(s) from the "trashcan" subdirectory, and can (and should) clean out the "trashcan" as appropriate. (Realize that this DELETE symbol can interfere with DELETE/GLOBAL and other similar DCL commands.) __________________________________________________________ 9.2 Why does SHOW QUOTA give a different answer than DIR/SIZE? DIRECTORY/SIZE doesn't take into account the size of file headers which are charged to your quota. Also, unless you use DIRECTORY/SIZE:ALL, you will see only the "used" size of the file, not the allocated size which is what gets charged against your quota. Also, you may have files in other directories. 9-1 Files $ DIRECTORY/SIZE=ALL/GRAND [username...] Grand total of D1 directories, F1 files, B1/B2 blocks. $ DIRECTORY/SIZZ=ALL/GRAND [-]username.DIR Grand total of 1 directory, 1 file, B3/B4 blocks. $ SHOW QUOTA User [username] has B5 blocks used, B6 available of B7 authorized and permitted overdraft of B8 blocks on disk If the user has no files in other directories and all file-headers are only 1 block, then the following should apply: B5=B2+B4+F1+1 If the diskquota has drifted out of synchronization, then the system-manager can force a quota rebuild-due to various factors, the quota file can potentially drift from the actual use over time, and a periodic rebuild can be performed at appropriate intervals. Also be aware that the DIRECTORY/SIZE command can report larger values than might otherwise be expected when used to evaluate files and/or directories that are alias links-such as the system roots on OpenVMS system disks-as the command reports a total that is cumulative over all of the files and directories examined, without regard for which ones might be alias entries and which are not. (In other words, a DIRECTORY/SIZE of an entire OpenVMS system disk will report a disk useage value larger than the (usually more accurate) value reported by the SHOW DEVICE command. This as a result of the alias entries linking each SYS$SYSDEVICE:[SYSCOMMON]SYS*.DIR directory file and the SYS$SYSDEVICE:[000000]VMS$COMMON.DIR file together.) __________________________________________________________ 9.3 How do I make sure that my data is safely written to disk? If your application must absolutely guarantee that data is available, no matter what, there's really no substitute for RMS Journaling and host- or controller- based shadowing. However, you can achieve a good degree of data integrity by issuing a SYS$FLUSH RMS call at appropriate times (if you're using RMS, that is.) If you're using a high-level language's I/O system, check 9-2 Files that language's documentation to see if you can access the RMS control blocks for the open file. In C you can use fflush followed by fsync. For details on disk bad block handling on MSCP and on SCSI disk devices, please see Ask The Wizard (ATW) topic (6926). o http://www.hp.com/go/openvms/wizard/ For additional information on the OpenVMS Ask The Wizard (ATW) area and for a pointer to the available ATW Wizard.zip archive, please see Section 3.9. __________________________________________________________ 9.4 What are the limits on file specifications and directories? A file specification has an aggregate maximum size of 255 characters at present. The node and device specification may be up to 255 characters each - file name and file types may be up to 39 characters each. File versions are from 1 through 32767, though 0 (latest version), -0 (oldest version) and -n (n'th previous version) can be used in most contexts. A file specification may not have more than 8 directories and subdirectories - while it is possible to create subdirectories of greater depth, accessing them is problematic in most cases and this should be avoided. Application developers should use OpenVMS-supplied routines for parsing file specifications - this ensures that changes in what is allowable will not tend to break your application. Consider that various parts of the file specification may contain quoted strings with embedded spaces and other punctuation! Some routines of interest are SYS$FILESCAN, SYS$PARSE and LIB$TRIM_ FILESPEC. For further information, see the OpenVMS Guide to File Applications. Performance of larger directory files improves (greatly) with OpenVMS V7.2 and later-operations on directory files of 128 blocks and larger were rather slower on earlier OpenVMS releases due to the smaller size of the directory cache and due to the directory I/O processing logic. 9-3 Files For fastest directory deletions, consider a reverse deletion-delete from the last file in the directory to the first. This reversal speeds the deletion operation by avoiding unnecessary directory I/O operations as the files are deleted. Tools such as the Freeware DFU can be used for this purpose, as can various available reverse-DELETE DCL command procedures. __________________________________________________________ 9.5 What is the largest disk volume size OpenVMS can access? One Terabyte (TB; 2**31 blocks of 2**9 bytes; 0x07FFFFFFF blocks). 255 volumes in a volume set. The largest contiguous allocation possible for any particular file is 0x03FFFFFFF blocks. Prior to the release of V6.0, the OpenVMS file system was limited to disk volumes of 8.38 GB (2**24 blocks, 16777216 blocks) or less. On some systems, there are restrictions in the console program that limit the size of the OpenVMS system disk. Note that data disks are not affected by console program limits. For example, all members of the VAXstation 3100 series are limited to a system disk to 1.073 GB or less due to the console, though larger data disks are possible. This limit due to the SCSI drivers used by and built into the console ROM to read the OpenVMS bootstrap files, and these same drivers are also used by OpenVMS to write the system crashump. There are numerous discussions of this VAXstation 3100 in the comp.os.vms newsgroup archives. Please use Google newsgroup search to search the archives for further details, for discussions of the workarounds, and for details of the potential for a simple failed bootstrap and particularly for discussions of the potential for severe system disk corruptions on crashes. Some SCSI disks with capacities larger than 8.58 gigabytes (GB) will require the use of an OpenVMS ECO kit (eg: ALPSCSI04_062 or later; see Section 14.26 for details) for new SCSI device drivers. Failure to use this ECO can cause "rounding errors" on the SCSI disk device capacity-OpenVMS will not use nor display 9-4 Files the full capacity of the drive-and "%sysinit-e-error mounting system device status equals 000008C4" (8C4 -> "%SYSTEM-?-FILESTRUCT, unsupported file structure level") errors during bootstrap. (One workaround for the bootstrap when the bitmap is located far into the disk is the use of INIT/INDEX=BEGIN.) The problem here involves the particular extensions and fields used for larger capacity disks within the SCSI specifications and within the various intepretations of same. For ATA (IDE) disk drives: o Versions of SYS$DQDRIVER *BEFORE* X-15 topped out at 8.455 GB. Fixed drivers (equal or greater than "X-15") were shipped in: o OpenVMS Alpha V7.2-1, and later o V7.2 UPDATE V1.0 ECO, and later o V7.1-2 UPDATE V1.0 ECO, and later o V7.1-2 UPDATE V3.0 ECO, and later o The newer SYS$DQDRIVER driver operates to disks up to 33 GB without (known) problems, and effectively works with rather larger disks (up to circa 137 GB) but is known to report an incorrect number of "cylinders" with disks above 33 GB. See Section 14.4.4.2 for additional ATA SYS$DQDRIVER information. Be aware that a known restriction in certain older versions of the Alpha SRM Console prevents booting most ATA (IDE) drives larger than 8.455 GB, depending on exactly where the various files are located on the volume. Updated SRM consoles for systems with SRM and ATA (IDE) drive support are (will be) available. (OpenVMS Engineering has successfully bootstrapped 20GB ATA (IDE) disks using the appropriate SRM console version.) 9-5 Files NOTE: All ATA-related disk sizes listed in this section are stated in units of "disk (base ten) gigabytes" (1 GB = 10^9 bytes) and NOT in units of "software (base two) gigabytes" (1 GB = 2^30 (1073741824.) bytes. See Section 14.26. Be aware that larger disks that are using an extension of SCSI-2- disks that are using a mode page field that the SCSI-2 specifications normally reserved for tape devices-to permit a larger disk volume size will require a SCSI driver update for OpenVMS, and this change is part of V7.1-2 and later, and also part of ALPSCSI07_062 and later. (These larger disks disks will typically report a DRVERR, or will see the volume size "rounded down".) SCSI disks larger than 16777216 blocks cira 8.455 GB (base ten); 8GB (base two) require this ECO, or require the use of OpenVMS Alpha V7.1-2 or later. Applications written in C can be limited to file sizes of two gigabytes and less, as a result of the use of longword values within C file operations, and specifically off_t. This restriction is lifted in OpenVMS V7.3-1 and later, and with the application of the C ECO kits available for specific earlier releases. The use of a longword for off_t restricts applications using native C I/O to file sizes of two gigabytes or less, or these applications must use native RMS or XQP calls for specific operations. Also see Section 14.14, Section 14.26. __________________________________________________________ 9.6 What is the maximum file size, and the RMS record size limit? RMS can store individual files of a size up to the maximum supported volume size. Under OpenVMS V6.0 and later, the volume size and the RMS maximum file size limit is 2**31 * 512 bytes-one terabyte (1 TB). "Use a volume set to provide a large, homogeneous public file space. You must use a volume set to create files that are larger than a single physical disk volume. (The file system attempts to balance the load 9-6 Files on the volume sets, for example, by creating new files on the volume that is the least full at the time.)" "You can add volumes to an existing volume set at any time. The maximum number of volumes in a volume set is 255." The RMS formats-sequential, relative, and indexed- are limited by the one terabyte maximum volume size. RMS relative files are further limited to a number of records that will fit in 32 bits-4 billion records. Sequential and indexed formats do not have a record limit. Also see Section 2.16.1, Section 14.26. __________________________________________________________ 9.7 How do I write CD-Recordable or DVD media on OpenVMS? How to create CD-R, CD-RW, DVD-R, DVD+R, DVD-RW, or DVD+RW media on OpenVMS? o Acquire a comparatively recent SCSI-based or ATA (IDE) CD-R or DVD-R/RW or DVD+R/RW drive. Older drives can be problematic, while newer drives are readily available, cheap and very fast. o Get LDDRIVER from the Freeware. Versions of LDDRIVER are latent in OpenVMS Alpha V7.3-1 and later. (Look within SYS$MANAGER:CDRECORD.COM for details.) o Get CDRECORD or CDWRITE or other similar recording tool. CDRECORD (part of CDRTOOLS), CDWRITE, and DVDRECORD (part of DVDRTOOLS) packages (DVDRECORD is a fork of CDRECORD) are freely available, and versions of CDRECORD are available on the Freeware V6.0 distribution. (http://www.hp.com/go/openvms/freeware/) Versions of CDRECORD (non-DVD) are latent in OpenVMS Alpha V7.3-1 and later. Commercial versions of CDDRECORD-with DVD capabilities-are also available for various platforms, and particularly a variant of CDRECORD known as CDRECORD-ProDVD. 9-7 Files Beware the tool chosen: some versions and configurations of CDRECORD can record DVD media, as can the DVDRECORD package, as can the commercial DVDwrite package. Many versions of CDRECORD cannot record DVD media, including the version of CDRECORD latent within OpenVMS and the version found on Freeware V6.0; these versions cannot record DVD media. o Build the contents of the disk on the LD device partition. o Use the chosen recording tool to record the contents of the LD partition directly onto the CD-R or CD-RW media. Alternatively, consider the following command on OpenVMS Alpha V7.3-1 and later: @SYS$MANAGER:CDRECORD.COM HELP While folks have had success getting PC-based CD-R/RW or DVD-R/RW or DVD+R/RW tools to work with OpenVMS partitions, it is far easier and more reliable to use the OpenVMS-based versions of these tools and directly- attached devices. More details: Creation of CD recordable or DVD recordable media under OpenVMS typically involves one of two approaches: the use of the optional CD-R (`Scribe') capabilities available for the InfoServer or other "offline" hardware packages (PC-based packages will be included in this), or the use of a host- based package such as the CDRECORD or CDWRITE13_VMS or other utilities, OpenVMS ports of common open- source tools made available by Dr. Eberhard Heuser- Hofmann and others. Dr. Heuser-Hofmann has DVDwrite , a commercial package which can record DVD media. (http://home.tiscali.de/dvd4openvms) OpenVMS can read ODS-2, ODS-5, and ISO-9960 format CD-ROMs. (If you are very careful, you can create a dual-format CD-R; a CD-R with both ODS-2 and ISO-9660 or both ODS-5 and ISO-9660 or both.) 9-8 Files InfoServer hardware configurations are no longer available from HP, but may potentially be acquired through other means; as used equipment. Packages related to the use of DVD archiving are also available, see the multi-volume capabilities of the DVDarchive/restore Freeware. http://www.geocities.com/SiliconValley/Lakes/9999/vmscdwri.html Additional information is available at the following sites: o http://www.djesys.com/vms/cdrom.html o http://www.cd-info.com/CDIC/Technology/CD-R/vms.html o http://www.faqs.org/faqs/cdrom/cd- recordable/part1/preamble.html o http://www.tmesis.com/CDrom/ o http://www.tditx.com/~odsiso/ U.S. Design offers a package that includes the tools necessary to create a CD or DVD-R with either ISO-9660 or ODS-2 format, for standalone CD-R/RW, DVD-R, or DVD+R/RW drives, for recent OpenVMS versions. Details are available at: o http://www.usdesign.com/ Also see Section 9.7.2 for details on access to recorded media on older CD-ROM drives. _____________________________ 9.7.1 CD and DVD notation, terminology? CD-ROM is pre-recorded Compact Disk media, and is the original and oldest CD format. The original CD media was physically stamped, a recording process that is now largely reserved to the highest-volume media reproduction requirements. CD-R is CD Recordable, a write-once storage medium that can be read by all but the oldest of CD drives; a format which can be read and often even recorded by most CD-RW drives. 9-9 Files CD-RW is CD ReWritable, a format which is readable by many CD drives and by most CD-R drives, and with media that can be recorded and re-recorded by CD-RW drives. CD media recording speeds are listed as multiples of 150 kilobytes per second, so a 10X drive records at 1500 kilobytes (1.5 megabytes) per second. 600 MB (70 minutes) and 700 MB (80 minutes) recording capacities are both widely available. The minutes designation is derived from the traditional audio-format recording capacity of the particular media. DVD-R/RW is the older of two common Digital Versatile Disk recording formats, and the DVD-R Recordable or DVD-RW ReWritable media can be read by many DVD drives. As with CD-R formats in older CD drives, older DVD and particularly first-generation DVD players may have problems reading this media format. DVD+R/RW is the newer of the two common Digital Versatile Disk recording formats, and the DVD+R Recordable or DVD+RW ReWritable media can be read by many DVD drives. Akin to DVD-R/RW media, older and particularly first-generation DVD drives can have problems reading this media format. The DVD Plus-series drives and media tend to record faster than Minus drives, as (as of this writing) the Plus (+) drives do not require an initial media formatting pass and the Minus (-) drives do. While the appropriate Plus (+) or Minus (-) DVD raw media must be chosen for the particular DVD recorder (and DVD recording drives that are compatible with and capable of using both Plus and Minus media are available), the resulting recorded media is generally readable (playable) in all recent DVD drives and DVD players, regardless of type. (Compatibility is best within the same media-series devices of course, but be certain to verify compatibility across devices regardless of the particular device or particular recording media chosen.) 9-10 Files Presently Plus (+) media is slightly more expensive than Minus (-), but with the prices of all CD and all DVD media continuing to consistently fall, the differences in DVD media costs are becoming irrelevent for all but the production of huge volumes of DVD media. The rated DVD recording speeds are in multiples of 1353 kilobytes per second, thus a DVD 1X drive is roughly equivalent to a CD 9X drive in I/O requirements and transfer speed. DVD drive recording speed can and does vary. DVD disk drive recording speed is limited by the rated recording speed of the media used, so the slower (and cheaper) DVD media will not record any more quickly in a faster drive. A 2.4X DVD drive loaded with 1X media will record at 1X. _____________________________ 9.7.2 Use of RRD42 and other older (embossed-media) CD drives? The RRD42 series SCSI CD-ROM drive is sufficiently old that it can have problems processing CD-R and CD-RW media. Other very old CD drives can have equivalent media compatibility problems when attempting to read (much) newer CD media and newer CD media technologies. These older CD drives are generally intended for use with the so-called embossed media, rather than with non-embossed recorded (recordable) media now in common circulation. Please consider using a slightly-less-ancient CD-ROM or CD-R or CD-RW drive when working with non-embossed recorded CD media. To paraphrase one knowledgable-though deliberately nameless-storage engineer, "The RRD42 drive is just past the drooling idiot stage". 9-11 Files __________________________________________________________ 9.8 What I/O transfer size limits exist in OpenVMS? The maximum transfer size is an attribute of the particular I/O device, controller and driver combination; there is no inherent limit imposed by OpenVMS (other than the fact that, today, byte counts and LBNs are generally limited to 32 bits). The maximum size of a device I/O request is limited by the value in UCB$L_MAXBCNT, which is set by the device driver based on various factors. (Also check the setting of the MAXBUF system parameter for buffered I/O transfers, and check the process quotas.) Currently, SCSI drivers limit I/O transfers to FE00(16) bytes, 65024 bytes (decimal). The reasons for this transfer size limitation are largely historical. Similarly, DSSI devices are limited to the same value, this for hardware-specific reasons. Transfers to HSC and HSJ device controllers via the CI are limited to 1,048,576 bytes. Client MSCP-served devices are limited to 65535 bytes-to help ensure that the I/O fragmentation processing happens on the client and not on the server system. Parts of the OpenVMS I/O subsystem are optimized for data transfers less than 64KB, because (obviously) most I/O operations are (substantially) less than that. OpenVMS can handle larger transfers, if the driver and the device can handle it. Also see Section 9.4, Section 9.5. __________________________________________________________ 9.9 Can I use ODBC to connect to OpenVMS database files? Yes, you can use various available third-party packages that permit remote ODBC clients to access RMS files and various commercial databases via the network. For RMS, consider acquiring one of the packages available from EasySoft, Attunity Connect (formerly known as ISG Navigator), Oracle (DB Integrator), SolutionsIQ, and Synergex. 9-12 Files For specific commercial databases (other than RMS, of course), contact the database vendor directly for assistance. __________________________________________________________ 9.10 If my disks are shown as VIOC Compatible, am I using XFC? Yes, you are using XFC caching. Disks that are using XFC caching use communication and coordination protocols that are compatible with the older VIOC caching implementation. With the initial implementation of XFC on OpenVMS, you can use the command SHOW MEMORY/CACHE to see no disks reported in full XFC mode; all disks shown will be listed in "VIOC Compatable Mode". If you have the OpenVMS system parameter VCC_FLAGS set to 2 and are using OpenVMS Alpha V7.3-1 or later, or are using OpenVMS Alpha V7.3 with the VMS73_XFC V2.0 ECO kit or later or with the UPDATE kits, you are using XFC. Another confusion: the XFC product version is and remains V1.0 in all released configurations, please do not confuse the internal XFC product version (displayed by various commands) with the version number associated with the various ECO kit(s). XFC V1.0 does not permit volumes to enter full XFC caching, as displayed by the "Vols in Full XFC mode" portion of the DCL command SHOW MEMORY/CACHE output. 9-13 _______________________________________________________ 10 OpenVMS Programming Information __________________________________________________________ 10.1 Modular Programming, Facility Prefixes and Symbol Naming? Please first review the OpenVMS Programming Concepts Manual and the Guide to Modular Programming manuals. Both are available within the OpenVMS documentation set, and provide details of the expected norms for OpenVMS programs. o Learn about the facility prefix, and use a the appropriate prefix uniformly throughout all external symbols, all logical names, and all files located in shared directories. The prefix and the use of the dollar sign (<$>) and the underscore (<_>) help avoid collisions with other products. Use of the dollar sign is reserved to registered products. o Please consider use of tools such as the Freeware SDL package, and the GNM package. These permit you to generate include files and message documentation akin to that of OpenVMS, providing users of your product with a familiar environment. o For product installations, consider use of the PCSI installation utility, and provide a product-specific configuration DCL command procedure (usually SYS$MANAGER:prefix$CONFIG.COM) if configuration is required. o The product startup file is usually named SYS$STARTUP:prefix$STARTUP.COM, and the shutdown file (if needed) is usually SYS$STARTUP:prefix$SHUTDOWN.COM. OpenVMS provides a registry for facility prefixes and for MESSAGE message compiler codes. To request a prefix and a message facility code for a product you are reselling, send your request in a mail message addressed to product[-at-sign-]hylndr.sqp.zko.dec.com, 10-1 OpenVMS Programming Information requesting the submission form and details of the registration process. Note Please do not request facility prefixes for products that local to your business, your site, or your system. Facility prefixes and message codes and the facility registration process are intended solely for HP products and Partner Products (and yes, even OpenVMS Freeware packages) that will be distributed across multiple OpenVMS customer sites. For a list of common coding bugs, please see the remainder of this section of the FAQ and specifically Section 10.22, please also see the Ask The Wizard topic (1661), and for information on debugging an OpenVMS application, please see topic (7552). o http://www.hp.com/go/openvms/wizard/ For additional information on the OpenVMS Ask The Wizard (ATW) area and for a pointer to the available ATW Wizard.zip archive, please see Section 3.9. __________________________________________________________ 10.2 Can I have a source code example of calling...? Please use the available SEARCH command on OpenVMS, and please remember to search the available resources, including the support databases and the newsgroup archives. Please also realize that most OpenVMS system services use similar calling sequences, meaning that an example of calling sys$getjpi can be used as an example for sys$getsyi and sys$getdvi. Students: please do not expect folks to write your homework for you. As for search resources: o SEARCH SYS$EXAMPLES:*.* target o SEARCH TCPIP$EXAMPLES:*.* target o http://askq.compaq.com/ o http://www.openvms.compaq.com/freeware/ o http://www.google.com/ 10-2 OpenVMS Programming Information OpenVMS programming documentation, including the numerous example programs found in recent versions of the OpenVMS Programming Concepts manual, is available: o http://www.openvms.compaq.com/doc/ o http://www.openvms.compaq.com/commercial/ As for details of argument passing, most OpenVMS system services and RTL routines pass string arguments by descriptor. Languages which support native string data types create descriptors automatically; those which do not (eg., C) require that you set them up explicitly. For further details on using descriptors and particularly for using descriptors from C, please see Section 10.13. There is extensive information available on how to call OpenVMS system services and OpenVMS Run-Time Library routines, including examples in numerous languages. Among the best available references are: o Your language's User Manual o OpenVMS Programming Environment Manual o OpenVMS Programming Concepts Manual o OpenVMS Programming Interfaces: Calling a System Routine o OpenVMS Calling Standard In addition, if you are a subscriber to the HP Software Information Network (available to those with a software support contract), the support database contains hundreds of worked examples of calling system services and RTL routines, including the one that seems to trip up almost everyone, SMG$CREATE_MENU. Arne Vajhøj has put together a collection of OpenVMS example programs. It can be found at: o ftp://ftp.hhs.dk/pub/vms/ 10-3 OpenVMS Programming Information Additional information and examples for OpenVMS are available via: o http://www.hp.com/go/openvms/wizard/ For additional information on the OpenVMS Ask The Wizard (ATW) area and for a pointer to the available ATW Wizard.zip archive, please see Section 3.9. and via: o http://www.openvms.compaq.com/freeware/ __________________________________________________________ 10.3 How do I get the arguments from the command line? If you're writing a program and want to accept arguments from a foreign command, you can use LIB$GET_ FOREIGN to get the command line and parse it yourself, or if you're programming in C, use the normal argc/argv method. To write an application which uses the normal DCL verb/qualifier/parameter syntax for invocation, see the description of the CLI$ routines in the OpenVMS Callable Utility Routines Reference Manual. It is possible to write an application which can be used both ways; if a DCL verb isn't used to invoke the image, the application parses the command line itself. One way to do this is to call CLI$GET_VALUE for a required parameter. If it is not present (or you get an error), call LIB$GET_FOREIGN to get the command line and do the manual parse. See also Section 8.1. __________________________________________________________ 10.4 How do I get a formatted error message in a variable? Use the SYS$PUTMSG system service with an action routine that stores the message line(s) in the variable of your choice. Be sure the action routine returns a "false" (low bit clear) function value so that SYS$PUTMSG doesn't then try to display the message (unless you want it to.) See the description of $PUTMSG in the System Services Reference Manual for an example of using an action routine. 10-4 OpenVMS Programming Information __________________________________________________________ 10.5 How do I link against SYS$SYSTEM:SYS.STB on an Alpha system? LINK/SYSEXE is the OpenVMS Alpha equivalent of linking against SYS.STB. This links against the base image: SYS$BASE_IMAGE.EXE Also see Section 10.11, particularly for pointers to the details on shareable images and shareable image creation. __________________________________________________________ 10.6 How do I do a SET DEFAULT from inside a program? The problem is that SYS$SETDDIR only changes the default directory - NOT the default disk. The default disk is determined by the logical SYS$DISK. If you want to change the default disk within a program, then call LIB$SET_LOGICAL to change the logical SYS$DISK. You will need to call both LIB$SET_LOGICAL and SYS$SETDDIR to change both default disk and the default directory! __________________________________________________________ 10.7 How do I turn my Fortran COMMON into a shareable image on Alpha? You need to add SYMBOL_VECTOR=(=PSECT) to your options file. On OpenVMS VAX all OVR/REL/GBL psects were automatically exported into the shareable image's Global Symbol Table. On OpenVMS Alpha you have to tell the linker that you want this done by means of the PSECT keyword in the SYMBOL_VECTOR options file statement. This has several advantages over OpenVMS VAX. First, you don't have to worry about the address of the psect when you try to create a new, upwardly compatible version of the shareable image. Second, you can control which psects, if any, are made visible outside the shareable image. By default, COMMON PSECTs in HP Fortran for OpenVMS Alpha (as well as most other OpenVMS Alpha compilers) are NOSHR. On VAX, the default was SHR which required you to change the attribute to NOSHR if you wanted 10-5 OpenVMS Programming Information your COMMON to be in a shareable image but not write- shared by all processes on the system. If you do want write-sharing, use: CDEC$ PSECT common-name=SHR in the Fortran source code (the CDEC$ must be begin in column 1) or a linker options file PSECT_ATTR statement to set the COMMON PSECT attribute to SHR. For further information, see the Linker manual. __________________________________________________________ 10.8 How do I convert between IEEE and VAX floating data? In OpenVMS V6.1 and later, the routine CVT$CONVERT_ FLOAT is documented in the LIB$ Run-Time Library Reference Manual, and can perform floating point conversions between any two of the following floating datatypes: VAX (F,D,G,H), little-endian IEEE (single, double, quad), big-endian IEEE (single, double, quad), CRAY and IBM System\370, etc. HP Fortran (all OpenVMS platforms) has a feature which will perform automatic conversion of unformatted data during input or output. See the HP Fortran documentation for information on "non-native data in I/O" and the CONVERT= OPEN statement keyword. There are floating-point conversion source code packages available for various platforms. For further floating-point related information, see: o http://www.hhs.dk/anonymous/pub/vms/collection/ieee.zip __________________________________________________________ 10.9 How do I get the argument count in a Fortran routine? On VAX, many programmers would use a MACRO routine which accessed the AP register of the caller to get the address of the argument list and hence the argument count. This was not guaranteed to work on VAX, but usually did. However, it doesn't work at all on OpenVMS Alpha, as there is no AP register. On Alpha systems, you must use a language's built-in function to retrieve the argument count, if any. In Fortran this is 10-6 OpenVMS Programming Information IARGCOUNT, which is also available in DEC Fortran on OpenVMS VAX. Note that omitting arguments to Fortran routines is non-standard and is unsupported. It will work in many cases - read the DEC Fortran release notes for additional information. __________________________________________________________ 10.10 How do I get a unique system ID for licensing purposes? Many software developers desire to use a unique hardware ID to "lock" a given copy of their product to a specific system. Most VAX and Alpha systems do not have a unique hardware-set "system ID" that can be used for this purpose. HP OpenVMS products do not use hardware IDs in the licensing methods, as many users consider a hardware-based licensing scheme to be negative attribute when considering software purchases. HP OpenVMS uses a software-based system called the License Management Facility (LMF). This provides for software keys (Product Authorization Keys or PAKS) which support capacity and user-based license checking. HP offers an LMF PAK Generator to CSA members-see Section 2.12. For information on licensing, please see Section 12.5. However, if a hardware-based method is required, the most common method is based on an Ethernet adaptor hardware address. Sample source code for implementing this is available at: o http://www.hp.com/go/openvms/wizard/ For additional information on the OpenVMS Ask The Wizard (ATW) area and for a pointer to the available ATW Wizard.zip archive, please see Section 3.9. 10-7 OpenVMS Programming Information __________________________________________________________ 10.11 What is an executable, shareable, system or UWSS image? Executable code in OpenVMS typically resides in an image-an image is a file-the file extension is typically .EXE-that contains this code. Common types of images include executable images, shareable images, system images, and protected (UWSS) images. Executable images are programs that can be directly executed. These images can grant enhanced privileges, with an INSTALL of the image with /PRIVILEGE, or can grant enhanced access with the specification of a subsystem identifier on the ACL associated with the image. Shareable images contain code executed indirectly, these images are referenced from executable images and/or from other shareable images. These images can not grant enhanced privileges, even with the use of INSTALL with /PRIVILEGE or a subsystem identifier. These shareable images can be dynamically activated (a LINK that occurs at run-time) via the LIB$FIND_ IMAGE_SYMBOL run-time library (RTL) routine. (See `protected images' for information on `privileged shareable images'.) System images are intended to run directly on the VAX or Alpha hardware-these are normally used for the kernel code that comprises an operating system. Protected images-also refered to as User-Written System Services (UWSS), or as privileged shareable images-are similiar in some ways to a standard shareable images, but these images include a `change mode' handler, and execute in an `inner' processor mode (privileged mode; executive or kernel), and code executing in inner modes has implicit SETPRV privilege. Must be INSTALLed with /PROTECT. Note that inner-mode code has restrictions around calling library routines, around calling various system services, and around calling code located in other protected or shareable images. 10-8 OpenVMS Programming Information Loadable images and device drivers are images that can be used to add code into the OpenVMS kernel. Pseudo- device drivers are a particularly convenient way to add executable code, with associated driver-defined data structures, into the kernel. The pseudo-device driver includes the UCB and DDB data structures, and a calling interface with support for both privileged and unprivileged access to the driver code via sys$qio[w] calls. A cookbook approach to creating OpenVMS shareable images is available at the URL: o http://www.hp.com/go/openvms/wizard/ For additional information on the OpenVMS Ask The Wizard (ATW) area and for a pointer to the available ATW Wizard.zip archive, please see Section 3.9. __________________________________________________________ 10.12 How do I do a file copy from a program? There are several options available for copying files from within a program. Obvious choices include using lib$spawn(), system(), sys$sndjbc() or sys$creprc() to invoke a DCL COPY command. Other common alternatives include using the callable convert routines and the BACKUP application programming interface (V7.1 and later). __________________________________________________________ 10.13 What is a descriptor? A descriptor is a data structure that describes a string or an array. Each descriptor contains information that describes the type of the data being referenced, the size of the data, and the address of the data. It also includes a description of the storage used for the data, typically static or dynamic. Descriptors are passed by reference. The following are examples of creating and using descriptors in C, with the use of the angle brackets normally expected by the C include statements deliberately altered in deference to HTML: 10-9 OpenVMS Programming Information #include {descrip.h} #include {lib$routines.h} #include {stsdef.h} int RetStat; char TxtBuf[TXTSIZ] struct dsc$descriptor StaticDsc = { 0, DSC$K_DTYPE_T, DSC$K_CLASS_S, NULL }; struct dsc$descriptor DynDsc = { 0, DSC$K_DTYPE_T, DSC$K_CLASS_D, NULL }; int DynDscLen = 255; $DESCRIPTOR( ConstDsc, "This is a string" ); /* finish setting up a static descriptor */ StaticDsc.dsc$w_length = TXTSIZ; StaticDsc.dsc$a_pointer = (void *) TxtBuf; /* finish setting up a dynamic descriptor */ RetStat = lib$sget1_dd( &DynDscLen, &DynDsc ); if ( !$VMS_STATUS_SUCCESS( RetStat ) ) return RetStat; /* release the dynamic storage */ RetStat = lib$sfree1_dd( &DynDsc ); if (!$VMS_STATUS_SUCCESS( RetStat )) return RetStat; Static descriptors reference storage entirely under application program control, and the contents of the descriptor data structure can be modified as required (by the application). OpenVMS routines do not modify the contents of a static descriptor, nor do they alter the address or length values stored in the static descriptor. (The term "static" refers to the descriptor data structure, and not necessarily to the storage referenced by the descriptor.) Dynamic descriptors reference storage under the control of the run-time library, and the contents of a dynamic descriptor data structure-once initialized- can only be modified under control of run-time library routines. The dynamic storage referenced by the dynamic descriptor is allocated and maintained by the run-time library routines. Various OpenVMS routines do alter the contents of the descriptor data structure, changing the value for the amount and the address of the storage 10-10 OpenVMS Programming Information associated with the dynamic descriptor, as required. Routines can obviously access and alter the contents of the storage referenced by the descriptor. OpenVMS languages that include support for strings or arrays are expected to use descriptors for the particular structure. Most OpenVMS languages, such as Fortran and BASIC, use descriptors entirely transparently. Some, like DEC C, require the programmer to explicitly create and maintain the descriptor. For further information on string descriptors, see the OpenVMS Programming Concepts manual, part of the OpenVMS documentation set. Fortran defaults to passing integers by reference and characters by descriptor. The following sites discuss mixing Fortran and C source code in the same application: o http://www.hhs.dk/anonymous/pub/vms/misc/FORTRAN_C_ CALL.COM o ftp://ftp.hhs.dk/pub/vms/misc/FORTRAN_C_CALL.COM __________________________________________________________ 10.14 How do I create a process under another username? Many server processes can operate within the context of the target user using privileges, using calls such as sys$chkpro and (more commonly in this context) sys$check_access as needed to determine if access would be permitted for the specified user within the current security model. With OpenVMS V6.2 and later, the persona system services (SYS$PERSONA_*) can be used to assume the persona of the specified user-these allow the server to operate as the specified user, in a controlled fashion. The persona services can be used as a "wrapper" around a sys$creprc process creation call, as well-this will create a seperate process entirely under the assumed persona. 10-11 OpenVMS Programming Information Information on the persona system services is included in the OpenVMS V6.2 new features documentation, and in the OpenVMS V7.1 and later system services documentation. These system services exist and are supported in OpenVMS V6.2 and later releases. Typical mechanisms for creating a process under another username include: o personna services around a sys$creprc call. See above. o via DECnet task-to-task, using explicit specification of username and password, or using a DECnet proxy. This creates a network-mode job under the target user. The network-mode job might do little more than a RUN/DETACH of an image passed in via task-to-task-task-to-task communications are fully available using strictly DCL-to-DCL processing, or using a compiled language and DCL, etc.) o SUBMIT/USER, or the username argument on the sys$sndjbc call. This creates a batch-mode job under the specified username. The batch-mode job might do little more than a RUN/DETACH of an image passed in via a parameter. o the UIC argument on the sys$creprc call. This mimics the UIC of the target user, and is certainly not the prefered mechanism for this task. o Via pseudo-terminals... There are likely a few other mechanisms around... There are various tools available from DECUS and other sources that allow various forms of user impersonation, as well. These tools will require version-dependent kernel code and enhanced privileges for some of (or all of) their operations. 10-12 OpenVMS Programming Information __________________________________________________________ 10.15 Why do lib$spawn, lib$set_symbol fail in detached processes? The processing within run-time library (RTL) calls such as lib$attach, lib$disable_ctrl, lib$do_command, lib$enable_ctrl, lib$get_symbol, lib$run_program, lib$set_symbol, lib$set_logical, and lib$spawn, is dependent on and requires the presence of a command language interpreter (CLI), such as DCL. Without a CLI present in the current process, these calls will fail with a "NOCLI, no CLI present to perform function" error. Detached processes typically do not have a CLI present. In place of lib$spawn, sys$creprc can often be used. The context of the parent process (symbols and logical names) will not be propogated into the subprocess when sys$creprc is used, though when there is no CLI present in the process this (lack of) propogation is moot. To create a detached process with a CLI, you must specify LOGINOUT as the target image as discussed elsewhere in the FAQ, or only use these calls (and any other calls requiring a CLI) from images that are running in an "interactive", "batch", or "other" mode process. Also note that the lib$spawn and the C system call will fail in a CAPTIVE login environment. The lib$spawn call can be gotten to work in this environment with the specification of the TRUSTED flag. __________________________________________________________ 10.16 Where can I obtain Bliss, and the libraries and supporting files? The Bliss language compilers and documentation are available on the OpenVMS Freeware distributions. Bliss language source code that contains the following statement: LIBRARY 'SYS$LIBRARY:STARLET.L32'; 10-13 OpenVMS Programming Information or similar requires the presence of the Bliss libraries. These libraries are created on the target system using the Bliss require files, and are built using the following Bliss commands: STARLET.L32 contains the public interfaces to OpenVMS: $ BLISS /LIBRARY=SYS$COMMON:[SYSLIB]STARLET.L32 - SYS$LIBRARY:STARLET.REQ LIB.L32 contains both the public and private interfaces to OpenVMS: $ BLISS /LIBRARY=SYS$COMMON:[SYSLIB]LIB.L32 - SYS$LIBRARY:LIB.REQ+SYS$LIBRARY:STARLET.REQ The equivilent files for Bliss64 are created with: $ BLISS/A64/LIBRARY=SYS$COMMON:[SYSLIB]LIB.L64 - SYS$LIBRARY:LIB.R64+STARLET.REQ+STARLET.R64 $ BLISS/A64/LIBRARY=SYS$COMMON:[SYSLIB]STARLET.L64 - SYS$LIBRARY:STARLET.R64 Some Bliss code may also require the OpenVMS VAX architecture flags. The following is the equivilent of the Alpha ARCH_DEFS.REQ module: ! ! This is the OpenVMS VAX version of ARCH_DEFS.REQ, and ! contains the architectural definitions for conditionally ! compiling OpenVMS Bliss sources for use on VAX systems. ! (If you should encounter compilation errors here, please ! seriously consider upgrading your Bliss compiler.) ! MACRO VAXPAGE = 1%; MACRO BIGPAGE = 0%; ! MACRO VAX = ! = 1 if compiled BLISS/VAX %BLISS(BLISS32V)%; ! = 0 if not compiled BLISS/VAX MACRO EVAX = ! = 1 if compiled BLISS/E* (Obsolete, old name) (%BLISS(BLISS32E) OR %BLISS(BLISS64E))%; ! = 0 if compiled /VAX /Inn MACRO ALPHA = ! = 1 if compiled BLISS/E* (New arch name) (%BLISS(BLISS32E) OR %BLISS(BLISS64E))%; ! = 0 if compiled /VAX /Inn MACRO IA64 = ! = 1 if compiled BLISS/I* (New arch name) (%BLISS(BLISS32I) OR %BLISS(BLISS64I))%; ! = 0 if compiled /VAX or /Ann 10-14 OpenVMS Programming Information MACRO ADDRESSBITS = %BPADDR%; ! = 32 or 64 based on compiler used Some Bliss code may require the definition files for the OpenVMS older LIBRTL routine lib$tparse, or the newer lib$table_parse call: $ BLISS /LIBRARY=SYS$COMMON:[SYSLIB]TPAMAC.L32 - SYS$LIBRARY:TPAMAC.REQ __________________________________________________________ 10.17 How can I open a file for shared access? When creating a file, it is often useful to allow other applications and utilities-such as TYPE-to share read access to the file. This permits you to examine the contents of a log file, for instance. A C source example that demonstrates how to do this is available in topic (2867) in the OpenVMS Ask The Wizard area: o http://www.hp.com/go/openvms/wizard/ For additional information on the OpenVMS Ask The Wizard (ATW) area and for a pointer to the available ATW Wizard.zip archive, please see Section 3.9. Depending on the environment, you may need to use C calls such as fsync and fflush, and-in specific cases- the setvbuf(_IONBF) call. __________________________________________________________ 10.18 How can I have common sources for messages, constants? Use the GNM tools on the OpenVMS Freeware to have common sources for MSG (message) files and SDML (Document) documentation files. Use the DOCUMENT command to convert the SDML documentation into the necessary formats (Text, Postscript, HTML, etc). Use the MESSAGE/SDL tool (latent in OpenVMS) to create an SDL file based on the messages. Then use the SDL tool (available on the OpenVMS Freeware) to convert the SDL file into language-specific definitions. (There is also a converter around to convert SDL into SDML, if you want to get pictures of the data structures for your documentation.) 10-15 OpenVMS Programming Information __________________________________________________________ 10.19 How do I activate the OpenVMS Debugger from an application? #include {lib$routines.h} #include {ssdef.h} #include {string.h} main() { char ascic_debug_commands[128]; char *dbgcmd = "*show calls;go;exit"; strcpy( ascic_debug_commands, dbgcmd ); ascic_debug_commands[0] = (char) strlen( dbgcmd ) - 1; lib$signal(SS$_DEBUG,1,ascic_debug_commands); return 1; } __________________________________________________________ 10.20 Dealing with Endian-ness? OpenVMS on VAX, OpenVMS on Alpha and OpenVMS on Intel IA-64 platforms (as well as all Microsoft Windows implementations and platforms) all support and all use the little-endian byte ordering. Certain Alpha microprocessors and certain Intel Itanium processors can be configured to operate in big-endian and potentially in bi-endian mode. HP-UX typically operates big-endian. With little-endian byte order, the least significant byte is always the first byte; the byte at the lowest address. With big-endian byte ordering, the byte storage order in memory is dependent on the size of the data (byte, word, longword) that is being referenced. Endian-ness is a problem has been solved many times before. Some of the typical solutions include htonl/htons and ntohl/ntohs in the standard C library and the TCP/IP Services XDR (eXternal Data Representation) libraries. One of the more recently introduced network formats, and one that is seeing extensive press and marketing coverage, is XML. 10-16