MPE Introduction and Tips for Unix Users

9/3/2015 MPE Introduction and Tips for Unix Users

http://www.robelle.com/tips/mpeforunix.html 1/13

MPE Quickstart for Unix UsersBased on the technical support calls that we are receiving, it appears that many HP 3000 systemsare being put in the care of staff with only Unix and Windows. So we have decided to write aseries of introductions to MPE for these lucky souls:

Part 1: Command CrossReference

Part 2: Login and Logoff

Part 3: Files

Part 4: File Content

Part 5: Scripts

MPE for UNIX Users, Part 1

Cross Reference from Unix Commands to MPE Commands

First thing you need to know is that MPE has Unixlike features integrated into it (via Posix), but most applicationsand software tools were written with the nonPosix features.

Basic MPE consists of a single shell (the command interpreter) and a file system that has only 3 levels (user,group, account) but has many file attributes including record size/type, max file size, extents and passwords(called lockwords).

The 3rd party product MPEX is an alternate shell, as is sh.pub.sys (the Posix shell).

(This cross reference list below is adapted from an inverse list by Neil Armstrong of Robelle.)

UNIX Command Equivalent MPE Command

sh command interpreter, mpex or posix shell

ksh command interpreter, mpex or posix shell

csh command interpreter, mpex or posix shell

.profile (sh) option logon in UDC

ksh $r, csh %! while do, do until

< file (input) < file

> file (output) > file

>> file (append) >> file (append)

<< hereis doc Not supported

scripts command files, udc

# at start of line comment

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command & Not supported, use job

cmd1 && cmd2 Not supported

$r(ksh),%!(csh) redo

x=v;export NAME setvar

abortjobkill [9] abortio

adduser newuser

at stream

batch stream

cancel deletespoolfile

cd chdir

chmod, passwd altacct

chmod, passwd altgroup

chmod file altsec file

chmod, passwd altuser

cp copy

cpio store

date showtime

dc calc

df, bdf discfree, dstat

du diskuse,report

echo echo,r print

ed editor, quad or qedit

env showvar

exit bye, exit, eoj

fbackup (hpux) store

fc 1 (sh) listredo

fi endif

ftp ftp, dscopy

if then else if then else

history listredo

hostname showme



login hello, job

logname showme

kill [9] abort

ld linkedit

lpq showout

lprm deletespoolfile

lpstat showout

ls listf, listfile

man help

mesg n set msg off

mkdir newdir,newacct,newgroup

more print

mv rename

printenv showvar

ps showproc, showq

pwd pwd

rwall warn

reboot h =shutdown

rm purge

rmdir purgegroup,purgeacct

sed editor, quad, qedit

setenv setvar

su god (3rd party vesoft)

symbolic link file equation, posix link

tar store

touch build

unset,unsetenv deletevar

users showjob

vi qedit

wall warn

whence help

whoami showme



while...do...done while do endwhile

write tell


HP 3000 Login and Logoff

By Robert Green, Robelle

So you are an experienced Unix/Windows SysAdmin who has been given the responsibility of looking after yourfirm's network of HP 3000s. And you have never seen the MPE operating system before.

One of the first things that you might do is log onto one of the systems, using the login instructions and passwordsleft you by the previous administrator.

Supposed you find the old admin's PC and on the desktop are icons for "PROD3000 Session" and "TEST3000session". If you don't find these icons, look for a program called Reflection, or Minisoft, or QCTerm. These are allsoftware emulators for the classic HP 2392/70092 terminals. Within the emulator, look for "Connect" in themenus and look for a list of server names.

(You can also connect to the 3000 with generic Telnet, but some capabilities will be lost.)

Let's click on the "Test" connection first! No need to experiment on what is probably the production system.

You should see a window that looks like a classic 24x80 computer screen. Then a colon should appear in thewindow with the cursor after it. This is the MPE command prompt).

:

You are being prompted for login, just like the login user prompt on Unix, except that in this case you need to typea Hello command.

:hello mgr.product

The command name is "HELLO", which means start an interactive session.

The User name is "MGR"; user names not like Unix user names.

The Account name is "PRODUCT", to which the User belongs.

You will usually be prompted for one or more passwords (the account can have a password and the user can alsohave a password). If you enter them correctly, you will see the colon (:) prompt again you are logged on. Unlikemost versions of Linux and Unix, you CAN use the backspace key in order to make corrections.

Enter the Showjob command to see that you are listed and see what other user sessions are active.

:showjob

Preentering Passwords Say the Account password is "xyz29b". You can enter it in response to the systemprompt, or you can embed it in the Hello command, using a slash between the account name and the password.

:hello mgr.product/xyz29b

Typically when logging on, most users let the system prompt them for the password as this is not echoed to thescreen.

User Names User and account names are limited to 8 alphanumeric characters and must start with an alpha.User names and commands are not case sensitive (i.e., mgr = MGR = Mgr). User names are not system wide as inUnix. They are only unique to an Account. For example, MGR.DEMO is a completely different user fromMGR.PRODUCT. MGR is not a unique user name, but MGR.PRODUCT is unique.

Accounts can have many user names, such as BOB.PRODUCT, BILL.PRODUCT, SALLY.PRODUCT, but oftenaccounts only have one User.

Why is that?

Because certain system functions, such as File Rename, can only be done by the user who originally built the file(the Creator this is called). If you have multiple Users in an Account, you sometimes have trouble performing allthe file tasks you wish to perform. For example, you logon as BILL.PRODUCT and rebuild a production file (you can



Purge the file without being the Creator, but when you build the new file you are now the new Creator). Then anightly production task logs on that night as BOB.PRODUCT and tries to rename the file. It fails because it is notthe Creator and the task fails as well, causing operational problems in the morning!

An Alternative to Users

There is an alternative to having several User names for an Account: use Session names instead.

:hello bob,mgr.product

The session name is "BOB" and it will show up on the Showjob command, but doesn't mean much of anything else.But all files in the PRODUCT account will be created by user MGR and can be renamed by any session name thatcan login as MGR. So everyone would login as MGR, but with a unique Session name.

Except! Vesoft has a 3rd party Security/3000 product that can create passwords on the Session name. This veryuseful, especially since the Vesoft Session names can be applied to any account if you like. In effect, this createssomething like a Unix user name that is mostly independent of file directories (yes, Accounts are also filestructures in MPE).

File Storage in Accounts and Groups

Your account also provides file storage. MPE files are stored in Groups, which are like subdirectories of Accounts.Unlike Unix, MPE files are not stored at the Account level, but only at the lower Group level (and there are no subGroups; sorry!)

For example, the PRODUCT account might have four groups:

PRODUCT account

PUB group this is a default group that all accounts haveDATA groupTEMP groupJOBS groupPROGRAMS group

Again, Group names are limited to 8 characters and are not case sensitive.

And of course there can be passwords on each Group, just as there can be on each Account and User. Securityaccess restrictions are attached to Accounts and Groups (such as "only someone who can login to the Account canread the files in this Account).

Each user can have a default logon group. When you logon you can see the files in your logon group using Listf orListfile:

:LISTF ‐ shows the MPE files in your current group:LISTFILE ‐ shows MPE and POSIX files in your current group

You can specify a different logon Group after the Account in the Hello command

:hello mgr.product,jobs

There is one thing that is quite confusing for new users. In the Hello command, the Group comes after theAccount, separated by a comma. But in a file name, the Group comes between the file name and the Account,separated by periods. For example,

MGR.PRODUCT,DATAUser.account,group

SALES2004.DATA.PRODUCTFile.group.account

To make things a bit more complex, the trailing Account and Group names can be left off from a file name and willdefault to your current login Account and Group.

SALES2004.DATA ‐ in your logon PRODUCT AccountSALES2004 ‐ in your logon DATA group of the PRODUCT account

These are all the same file.

Mapping MPE Files into Posix Space

Since MPE also has Posix files, how does the MPE file system map into the Posix structure? It is actually quitesimple. All MPE names are converted to uppercase.

/PRODUCT ‐ the Account is located off the Root node /PRODUCT/PUB ‐ the default "PUB" Group/PRODUCT/DATA ‐ the DATA Group



/PRODUCT/DATA/SALES2004 ‐ a file in the DATA group

Effectively, the MPE Account is treated as a root directory on Posix, with the Groups treated as subdirectories ofthe Account. Very neat in fact, the system allows Posix files to be created within MPE Account/Group space, butthose files cannot be "seen" by ordinary MPE commands such as Listf (only the new commands such as Listfile).

Help Yourself

Instead of "man" pages on Unix or F1 in windows or other help files, MPE has it's own Help facility, which can beaccessed by:

:help

That is enough for your first time on MPE. Logoff now with the Bye command.

:bye


The Complex World of Files


In part 2, we explored the directory structure of MPE a bit to explain about logging on. In part 3, we look at files tosee how they are different from files in Unix.

The File System is one area where MPE is really different from Unix. And much more complicated. Let's start bybuilding a file,

:build abc

Seems just like

touch abc

in Unix, right? Wrong the

build

command has lots of optional parameters, all with defaults.

To see what we "built", we use the

listf

command (this is like

ls ‐l

in Unix):

:listf abc,2ACCOUNT= GREEN GROUP= BOB

FILENAME CODE ‐‐‐‐‐‐‐‐‐‐‐‐LOGICAL RECORD‐‐‐‐‐‐‐‐‐‐‐ ‐‐‐‐SPACE‐‐‐‐ SIZE TYP EOF LIMIT R/B SECTORS #X MX

ABC 128W FB 0 1023 1 0 0 *

The

listf,2

option shows the most common attributes of an MPE file. Other options show access dates, creator name, andother attributes.

FILENAME file names are limited to 8 characters and case is not significant; just as explained for user andaccount names in part 2.

CODE a file type number that tells you what type of content the file should hold. Some of these have mnemoniclabels, but underneath all are integer values. For example, 111 is a QEDIT workfile, 1030 is an NMPROG file. Thedefault code is 0 (i.e., nothing special). For a list of file codes used by HP and thirdparty vendors, go to

http://www.robelle.com/smugbook/filecode.html

http://www.robelle.com/smugbook/filecode.html



A negative file code makes the file a "privileged file" which can only be opened by a program running in privilegedmode (in user mode, programs cannot access or change data that is not their own; in privileged mode, programscan get at data outside the program; the operating system runs in a special privileged mode). The most wellknown example of privileged files in MPE is database files; they can only be accessed by going through thedatabase API (or by going into privileged mode, access to which is restricted by system security).

SIZE specifies the record size. Unix files do not have records; a file is just a stream of bytes. But MPE files have arecord structure (except for Posix bytestream files, which are like Unix files).

The record size is the amount of data that is read or written by a single call to MPE's FREAD or FWRITE intrinsic.An intrinsic is an MPE system routine, just like fread and fwrite in Unix.

The default record size is 128 words (which is 256 bytes, because the original HP 3000 was a 16 bit machine).

TYP FB means "fixed, binary". Fixed is the record format, meaning that each record contains exactly 128 words.Another option is V for Variable. Binary means that if a fixed record is incomplete, it is filled out with binary zero.The alternative A for Ascii means that incomplete records are filled with blanks. Also, when a file is Ascii, the SIZEcolumn will show the record size in Bytes (128B for example).

EOF tells you how many logical records have been written into the file (actually, it shows you the highest recordnumber that has been written). An empty file like this always shows 0 for the EOF.

LIMIT tells you the maximum number of logical records that can be written into the file (for variable lengthrecords this number is based on writing maximum length records, so it is often not the real limit). The LIMITconcept is completely alien to Unix. In MPE, a program can fail because it attempts to append a record to a filethat has reached its LIMIT, even though the system still has lots of free disk space.

R/B Records Per Block. In the original MPE you specified the number of logical records to be stored in a physicalblock of disk storage (a block was the amount normally transferred to/from disk). Over the years, the internals ofMPE have changed so much that this attribute does not mean much anymore, although it is maintained forcompatibility.

SPACE, SECTORS Logical disk space in MPE is measured in "sectors", which are 256 bytes each. As records arewritten into a new file, disk space is allocated in chunks called "extents" and this SECTOR value goes up. Again thisunit of measure is just for historical compatibility, since the current version of MPE actually manages disk space inpages, which are much larger. If you would like more explanation, please see

http://www.robelle.com/smugbook/pages.html

SPACE, #X MX disk space is allocated in extents, so #X is the number of extents currently allocated to the fileand MX is the maximum number that can be allocated. In the old days, MX was limited to 32 and #X went from 0to 32, at which point the file was full. And all extents, except the last one, were the same size.

Now the default MPE file has * for MX, which means that there is no effective limit on the number of extents.However, you still must have a fixed number for the LIMIT on logical records, even if that number is 2 billion!

Be warned that if you create a file with a fixed number of extents and a large LIMIT in logical records (for example,

build def;disc=123456789,32

), you may very well get an error such as "extent size too large".

Here are some additional file attributes for MPE:

USER LABELS are optional 256 byte areas for control information that are tacked onto the start of the file space.Typical examples are SelfDescribing files and Powerhouse subfiles, where the data dictionary is stored in the userlabels; this leaves all the logical records with the same data format. Historically they come from old mainframesystems, even going back to tapebased systems where the tapes had labels on them! They are most commonlyused in COBOL systems that were migrated from these old IBM systems. The typical file on MPE has 0 user labels.

CCTL stands for Carriage Control. A file with the CCTL attribute has an extra byte at the beginning of each logicalrecord which tells whether to do a page eject, single space, double space, or more obscure function before (orafter) printing the record. These are not the same as Spool files; they are more like antique portable print files.This capability goes back to old line printers, which had program tapes, which could be customized for specialforms such as preprinted invoices. What is interesting is that most of MPE's simulated line printer functionality stillworks on Deskjet printers and terminal screen emulators because MPE converts the CCTL codes into terminalcodes.

The default for an MPE file is

build abc;nocctl

. For more on CCTL files:

http://www.robelle.com/smugbook/pages.html



http://www.robelle.com/smugbook/cctl.html

TEMP stands for temporary files. On Unix, temporary files are just permanent files that are built in a specialdirectory, such as

/var/temp

. Unix does not normally have an automatic cleanup for temporary files after a user logs off. MPE temp files aredifferent because they are actually temporary! They are not recorded in the regular file directory, but in a tempdirectory that is attached to the user logon (interactive session or batch job). Any process created during the logoncan access the temp files of that session/job and when the session/job logs off, the temporary file space isreturned to the system.

MPE even has processtemporary files that are private to a program and go away when that process terminates oraborts. These are called NEW files and can be saved as Temporary or Permanent files by the process.

CIR, MSG stands for Circular or Message file. MPE has special files where the current record pointer either wrapsaround (CIR) or moves in such a way that a fread erases the record that is read (MSG).

KSAM, KSAMXL these are indexed sequential files, with KSAM being the original, classic MPE version and KSAMXLbeing the rewrite for the RISC processors and MPE/XL (now called MPE/iX).

So, you can see that our simple build abc is actually a much more complex command:

:build abc;rec=128,1,F,binary;disc=1024;code=0; &std;ulabel=0;nocctl

Tune in next month for details on how to work with the content of all these file types!


Examining the Content of Files


In part 3, we looked at files. In part 4, we learn how to look at file content.

If you are a Unix person, the first thing you look for is more, and the MPE equivalent is Print:

Print filename

Print displays the lines of the file on $Stdlist, stopping every screenful and asking if you want more. You cananswer Y or N. In Unix, you usually press Space for Yes or "go on", but in MPE you usually press Enter.

Print is only useful for files of text data. For looking at binary data, the basic tool provided by MPE is Fcopy.

The main purpose of Fcopy is "file copy", but it can also display binary data in Hex or Octal format and do somesimple data selection. Fcopy is a subsystem, while Print was an MPE command. You enter the subsystem with theFcopy command and it has its own commands. You exit the subsystem with the Exit command (some latersubsystems used Quit as Unix started to influence MPE). Other subsystems of MPE include Editor and Sort.

:fcopy >from=filename;to=;hex;char >from=filename;to=;octal;char >exit :

Notice that when you enter Fcopy, the prompt character changes from Colon to Greater Than. This is typical aColon prompt always indicates that an MPE command is expected.

The first command displays each record of filename on $Stdlist as a hexadecimal dump and as a character dump(Char replaces nonprinting characters such as Carriage Return and Linefeed with Period to avoid disrupting yourdisplay).

The second command converts the record data to Octal instead of Hex.

The third command, Exit, gets you back to MPE.

Fcopy introduces you to a couple of other MPEisms.

1) You use ControlY to stop the listing; this is true for all MPE subsystems, but for MPE commands use the Breakkey if ControlY does not work.

http://www.robelle.com/smugbook/cctl.html



2) The syntax of the Fcopy commands is different from that of MPE commands; unfortunately, this is true of mostall MPE subsystemsthey all have slightly different command syntax styles.

Fcopy also allows you to select specific records numbers, or records that have a specific text string at a givenlocation. You append the Subset option to your copy task:

subset=1/10 subset="string", column [,EXCLUDE]

But Fcopy cannot select on binary fields or look for multiple strings.

For complex text searches, the Unix user turns to grep, and MPE has grep in the Posix shell. To enter the shell,you type "sh.pub.sys", which is an implied run on the "sh" program in the "pub" group of the "sys" account. Whenyou are in the Posix shell, you must use Posix filenames, not MPE filenames. So sh.pub.sys would be/SYS/PUB/SH.

For looking at file contents, the Posix head and tail commands are very handy (show the start of a file or the endof it).

Another MPE subsystem that can be used for examining text files is Editor.

:editor /text filename /find "string" /list * /exit

Notice that the prompt character is Slash, while Fcopy used Great Than.

Editor has a fairly powerful set of search options. In this example, Find looks for the next line that contains thestring at any location within the line. But to find all the lines that match, you must program the Find in a Whileloop.

MPE also has a wide variety of text tools from thirdparties that you will likely on your system, such as Qedit, anEditor replacement that also provides fullscreen editing (see www.qedit.com).

:qedit.pub.robelle /text filename /list "string" /exit

The commands are similar to Editor, but the default behavior is to treat any occurrence of a string as a request forall the lines that contain that string. Qedit borrows concepts from Fcopy and other tools. For example, you candisplay the selected lines in Hexadecimal if you wish:

/list $hex $char 1/10

Or ignore case and only search certain columns on string matches:

/List "enhancement" (Upshift 20/50)

Or search for up to 10 strings on a single command.

/List "problem" or "bug" or "help"

Magnet is our method of choice for searching a group of files, because it is so fast. It is a part of "Nuggets (akaToolboxes)", a package of MPE utilities written by Stan Sieler and friends, and sold by Lund. By default, Magnetlists the files with a filecode of zero (regular files) or 111 (Qedit files) in your logon group that contain at least oneline with the target string. Use the F option to specify filesets, the C option to ignore case, L to list lines thatmatch, and E to show Editorstyle line numbers. For example, to search the SRC group of the logon account for"fopen", ignoring case:

:magnet "‐[email protected] fopen ‐c ‐l ‐e"

For more details on Magnet, see

http://www.allegro.com/products/hp3000/toolboxes.html

MPEX is a thirdparty tool from Vesoft that extends the MPE command shell to work on sets of many files, ratherthan just one file. It is very flexible and allows selections such as "files bigger than 1 GB and untouched in over ayear". MPEX allows you to select files based on searching text within the files:

%PRINT [email protected];SEARCH="CUSTNUM";NUM

MPEX also allows searching for lines containing alternate strings, or more than one string, or almost any searchlogic:

%PRINT @.SOURCE;SEARCH="PROCEDURE" or "FUNCTION";NUM %PRINT @.SOURCE;SEARCH="PROCEDURE" and "FNAME" %PRINT @.JOB;SEARCH="!JOB" and NOT "MANAGER.SYS"

http://www.qedit.com/

http://www.allegro.com/products/hp3000/toolboxes.html



There are many more options (caseless, look for delimiters, look for a delimiter on the left only, etc.).

Database Files

What does it mean when you get this error:

:print store01.db ^ PRIVILEGED FILE VIOLATION (FSERR 45) The PRINT command failed. (CIERR 9080)

This means is that you tried to open a database file in usermode. These are "privileged files" that can only beopened in Priv Mode. This restriction ensures the integrity of the database structure by forcing all access throughsystemapproved tools or APIs.

Query is a database tool found on every HP. It can do selection, but only works on databases, not disk files. Asimple Query task would be:

:query >FIND order‐detail.order‐date GT 20040101 >REPORT ALL

Query has numerous report formatting options, including sorting, level breaks, item formatting, etc. However, theoutput is intended for a printer, so most of the formatting options have that in mind. It is possible to redirect thisoutput to a disk file, but Query was written before anyone asked for output to an Excel spreadsheet.

Suprtool is a thirdparty product (see www.suprtool.com) that is found on many HP 3000 systems; it works onboth databases and disk files. Like Fcopy it can copy or print records using Char,hex dump, but it can do much,much more. It can do sophisticated selection and sort the records. For example, to select all the Open orders, sortthem, eliminate duplicates, write them to a disk file for further processing, and print the fields of each selectedentry, use:

:suprtool.pub.robelle >base orders.db >get order‐detail >if order‐date > "20040101" and order‐status="O" >sort order‐num >dup none >output opensel >list >xeq

Suprtool provides a Define and Item command to describe the record format of a file so that it can be treated likea database. Or to more accurately describe a database (i.e., define subfields, date fields, and decimal places).The output can go to the printer, or to a disc file, or to the database, or to an Excel spreadsheet, or to almost anyother format of file.


Shell Scripts


Both MPE and Unix have scripts, but there are a number of differences. From a paper by Ken Robertson when hewas at Robelle:

"Before MPE/iX, there was a runtime environment for the MPE/V class of HP computers called theCommand Interpreter (CI). This MPE/V CI had limited programming capability, with If / Else constructsand numeric variables limited to values between 0 and 65535. The basic interface of the MPE/V CI(Command Interpreter) was ported to MPE/iX machines, and beefed up so it would be usable as a runtime shell.

The MPE/iX command interpreter has a generous command set, pushing the shell into the realm of a trueprogramming tool. Its ability to evaluate expressions and to perform I/O on files allows the enduser to performsimple dataprocessing functions. The CI can be used to solve complex problems. Its code, however, isinterpreted, which may cause a CI solution to execute too slowly for practical purposes.

Command files are a collection of commands in flat files, of either variable or fixed length record structure, thatreside in the MPE or POSIX file space. Basically, command files are what you could call MPE Macros. Anything thatyou can do in the CI interactively, you can do with command files, and then some. You can use command files insituations that call for repetitive functions, such as recompiling source code, special spooler commands, etc.Command files are also great when you want to hide details from the enduser.

http://www.suprtool.com/



A command file is executed when its name is is typed in the CI, or invoked from a command file or programmingshell. Just as in program execution, the user's HPPATH variable is searched to determine the location of thecommand file."

MPE Scripts Versus Unix Scripts

For the average task, the MPE scripting language is easier to read and understand than most Unix scripts. Forexample, command line parameters in MPE have names, just like in regular programming languages.

Of course, there are several script languages on Unix and only one on MPE! On Unix you can write shell scripts forany of the many shells provided (C shell, Bourne shell, ksh, bash, etc). Although there is also now a Posix shell onMPE, most scripts are written for the CI. Several thirdparty tools, such as Qedit and MPEX, emulate HP scriptingand integrate it with their own commands.

A command file can be as simple as a single command, such as a Showjob command with the option to only showinteractive sessions (and ignore batch jobs):

:qedit /add 1 showjob job=@s 2 // /keep ss /e :

You have created a command file called SS when you type

SS

you will execute

showjob job=@s

On MPE, the user needs read (r) or execute access (x) to SS. On Unix you normally must have x access, not just raccess, so you do a

chmod +x

on the script. This is not necessary in MPE, although, if don't want users to be see the script, you may removeread access and enable execute access.

Structure of a Command File (aka CI script)

A script is an ASCII file with maximum 511 byte records. Unlike Unix, the records may contain an ASCII sequencenumber in the last 8 columns of each line. The command file consists of 3 optional parts:

1. Parameter line with a maximum of 255 arguments

parm sessionnumber parm filename, length="80"

2. Option lines

option nohelp,nobreak option list

3. The body (i.e., the actual commands)

showjob job=!sessionnumber build !filename;rec=‐!length,,ascii

In MPE scripts, there is no inline data, unlike Unix 'hereis' files.

Parameters

Notice in the example above that parameters are used with an exclamation (!), as opposed to the $ in Unix. Thesame is true for variables. Parameters are separated by a space, comma or semicolon. All parameter values areuntyped, regardless of quoting.

In a typical Unix script, the parameters are referenced by position only ($1, $2, $3, ...). In an MPE script, theparameters have names, as in the function of a regular programming language, and can also have default values.In Unix you use $@ for all of the parameters as a single string; in MPE you use an ANYPARM parameter toreference the remainder of the command line (it must be the last parameter).

Here is a script from Beechglen to translate "subsys" and "err" numbers from MPE intrinsics into error messages.



The subsys and error numbers are passed in as parameters:

parm p_subsys=108,p_error=63 comment decodes subsys and info error codes. comment By Mike Hornsby from Beechglen Development. comment Thanks to Stan Sieler from Allegro. comment setvar subsys hex(!p_subsys) setvar error hex(!p_error) comment the hex conversion allows for negative numbers comment the #32765 is magic according to Stan! setvar cmd "wl errmsg(#32765,!subsys);wl errmsg(!error,!subsys);exit" debug !cmd

As you can see above, the Setvar command assigns a value to parameter or to a new variable. But there are alsosystem predefined variables. To see them all do

Showvar @;hp

. To get information on variables, do

help variable

and to get help on a specific variable, such as "hpcmdtrace", do

help hpcmdtrace

(set TRUE for some debugging help).

In most MPE commands, you must use an explicit exclam ! to identify a variable:

build !filename

However, some MPE commands expect variables, and thus do not require the explicit !. For example, Setvar, If,ElseIf, Calc, While, and for all function arguments, and inside ![expressions].

Warning: variables are "session global" in MPE. This means that if a child process, or scripts, changes a variable, itremains changed when that child process terminates. In Unix you are used to the idea that the child can dowhatever it likes with its copy of the variables and not worry about any external consequences.

Of course having global variables also means that it is much easier to pass back results from a script! And this isquite common in MPE scripts.

Options

Options allow you to list the commands as they are execute (option list), disable the Break key (option nobreak),enable recursion (option recursion), and disable help about the script (option nohelp).

The Body of the Script

Here is a script body that shows active process information (from Beechglen):

WHILE HPCONNSECS > 0 IF FINFO("SQMSG",0) PURGE SQMSG,TEMP ENDIF BUILD SQMSG;REC=‐79,,F,ASCII;TEMP;MSG FILE SQMSG=SQMSG,OLDTEMP SHOWQ;ACTIVE >*SQMSG SETVAR PINLIST "" WHILE FINFO("SQMSG",19) <> 0 INPUT SQLINE < SQMSG IF POS("#",SQLINE) <> 0 THEN SETVAR PIN RTRIM(STR(SQLINE,47,5)) SETVAR PINLIST "!PINLIST" + "," + "!PIN" ENDIF ENDWHILE IF FINFO("SPMSG",0) PURGE SPMSG,TEMP ENDIF BUILD SPMSG;REC=‐79,,F,ASCII;TEMP;MSG FILE SPMSG=SPMSG,OLDTEMP SETVAR PROC "SHOWPROC PIN="+"!PINLIST"+";SYSTEM >*SPMSG" !PROC WHILE FINFO("SPMSG",19) <> 0 INPUT SPLINE < SPMSG IF POS(":",SPLINE) <> 0 THEN ECHO !SPLINE ENDIF ENDWHILE PAUSE 30



ENDWHILE

This example shows many of the commands commonly used in scripts: If, While, Pause, Setvar, Input and Run.Other commands you will see are Echo, Deletevar, Showvar, Errclear

Handling Errors

In most Unix scripts, if a step fails, you check for an error with an Ifconditional and then take some action, one ofwhich is ending the script. Without an If, the script continues on, ignoring the error.

In MPE, the default action when a step fails is to abort the script and pass back an error. To override thisdefault, you insert a Continue command before the step that may fail. You then add If logic after the step to printan error message and perhaps Return (back 1 level) or Escape (all the way back to the CI).

continue build newdata if cierror<>100 then print "unable to build newdata file" print !hpcierrmsg return else comment ‐ duplicate file, okay endif

You can set HPAUTOCONT to TRUE to continue automatically in case of errors, but this can be dangerous. Thedefault behavior at least lets you know if an unexpected problem occurs.

User Defined Commands (UDC)

UDCs are like Command File scripts, except that several are combined in a single "catalog" file. They are an olderfeature of MPE, so you may see them in older applications even when scripts seem like a better solution. Theprimary reason that they are still useful is that they support Option Logon, which invokes the command when auser logs onto the system.

More Information

Tim Ericson's collection of UDC's and Command files has recently been resurrected and republished in the publicdomain at:

http://www.3k.com/index_cmd.html

The Beechglen web site has a number of useful scripts, some mentioned above:

http://www.beechglen.com/mpe/downloads.html

http://www.3k.com/index_cmd.html

http://www.beechglen.com/mpe/downloads.html

Documents

MPE Introduction and Tips for Unix Users