topic Re: How to extract string from command output? in Operating System - OpenVMS

How to extract string from command output?

Andrew Yip — Thu, 05 Jan 2006 03:54:05 GMT

Hi Gurus,

I'm using a OVMS v5.5 and i'm trying to extract a particular string and word from a command output, for example:
==============================================
$ mem dis /int
Programs in 68040 Main Memory

File name Id Type Status
--------- -- ---- ------
P2780232N111AC1.INT
2 sum3 used
P1TD703130K10A4.INT
1 sum3
LIANG.INT 6 sum3 used

Total 3 files 380928 bytes. 2409472 bytes free.
$
==============================================

Now, how do i extract the free bytes information from the above output. In unix scripting, i would usually use the grep function. Can anyone offer help? Thanks!

Best Regards,

Andrew
______________________________________________

Re: How to extract string from command output?

Wim Van den Wyngaert — Thu, 05 Jan 2006 04:28:11 GMT

Use this as an example.

$ define/us sys$output 'ct_workf'
$ show proc/mem
$ open/read x 'ct_workf'
$r30:
$ read/end=e30 x x_rcd
$ x_rcd=f$ed(x_rcd,"compress")
$ pos=f$loc("Free Space (bytes)",x_rcd)
$ if pos .ne. f$len(x_rcd)
$ then
$ cur=f$int(f$elem(4," ",x_rcd))
$ if cur .ne. prevcur then d "Current free space : ''cur'"
$ prevcur==cur
$ if cur .le. 5000 then say "''CUR' free bytes process dynamic memory"
$ endif
$ goto r30
$e30:
$ close x

Re: How to extract string from command output?

Andrew Yip — Thu, 05 Jan 2006 07:23:25 GMT

Hi Wim,
Thanks for your post, but do you have a simplier explanation for your example? I don't understand it very well. I'm pretty new to OVMS. Thanks!

Re: How to extract string from command output?

Hein van den Heuvel — Thu, 05 Jan 2006 07:46:08 GMT

Hello Andrew, welcome to the OpenVMS group.

In Wim's example he solves a much similar problem, and leaves it up to you to translate to your exact needs. I encourage you to study it and learn. The main 'trick' he uses, is a classic DCL scripting technique of searching for a substring. This returns the string length if not found.

Here is a solution taylored to your case where i start by loooking for an element, splitting the line by spaces. Compare the f$elem(7," ",record) with $7 in AWK.
P1 is the name of a file (SYS$PIPE if needed,

$close/nolog file ! In case it was left open
$open file 'p1
$loop:
$read /end=not_found file record
$if f$elem(7," ",record).NES."bytes" THEN GOTO loop
$if f$elem(8," ",record).NES."free." THEN GOTO loop
$bytes = f$elem(6," ",record)
$SHOW SYMBOL bytes
$CLOSE file
$EXIT
$not_found:
$WRITE SYS$OUTPUT "line with free bytes not recognized"
$CLOSE file

Be sure to read the fine HELP LEXICAL and help in genral, and try to get a 'programming in DCL' book in print.

Now 5.5 is a terribly old VMS version. I don;t suppose there is any hope to upgrade that?
Can you get PERL for 5.5?
If so, the solution of course can become nuch more like Unix:

$ perl -ne "print $1 if /(\d+)\s+bytes free.$/" tmp.tmp

hth,

Hein.

Re: How to extract string from command output?

Robert Gezelter — Thu, 05 Jan 2006 07:50:56 GMT

Andrew,

Basically, the script that Wlm posted scans the output one line at a time, looking for the string "Free Space (bytes)", and then extracting the information from the line. The output is re-routed from the standard output device, by default the terminal, to a scratch file contained in the variable "ct-workf". The command SHOW MEMORY is used to generate the output information to parse.

The processing and analysis of the lines is done using DCL lexical functions. These are documented in the DCL Dictionary (the documentation for the recent releases in available in PDF and HTML versions on the OpenVMS www site at http://www.hp.com/go/opemvms; while some new functions, and options have been added since 5.5, the manual is still usable; the information is also available online by using the command HELP LEXICAL).

I also did a presentation on the basics of DCL scripting at the Fall 1995 DECUS Symposium, you can get the slides from that session via http://www.rlgsc.com/decus/usf95/index.html).

- Bob Gezelter, http://www.rlgsc.com

Re: How to extract string from command output?

Daniel Fernandez Illan — Mon, 09 Jan 2006 04:45:47 GMT

Andrew

Other solution is use pipe and search commands.
For example:
PIPE SHO PROC/MEM | SEAR SYS$INPUT "Free Space"

Happy new year.
Saludos.
Daniel.

Re: How to extract string from command output?

Jan van den Ende — Mon, 09 Jan 2006 05:09:37 GMT

Daniel,

look at the original question: VMS V5.5

That does not yet support PIPE.

Proost.

Have one on me.

jpe

Re: How to extract string from command output?

Daniel Fernandez Illan — Mon, 09 Jan 2006 05:21:33 GMT

Sorry Jan
I am landing from my vacations (much beer and wine) and I am still slept.

Sorry.
Saludos.
Daniel.

Re: How to extract string from command output?

Daniel Fernandez Illan — Wed, 11 Jan 2006 14:09:25 GMT

Other solution without use PIPE

$DEFINE SYS$OUTPUT MEMO.TXT
$SHO PROC/MEM
$DEASS SYS$OUTPUT
$SEAR MEMO.TXT "Free Space"
$DELE MEMO.TXT.*

Saludos.
Daniel.

Re: How to extract string from command output?

Phil.Howell — Thu, 12 Jan 2006 00:48:45 GMT

Before there was pipe, I used @tt (undocumented) to redirect output
for example

$@tt /out=out.txt
$mem dis /int
$exit
$search out.txt "bytes free" /out=line.txt

line.txt then contains the total line
you can open and read the file into a symbol
and then use f$locate and f$extract to get your integer.
Phil

Re: How to extract string from command output?

Andrew Yip — Thu, 12 Jan 2006 04:25:40 GMT

Hello Hein,

Thanks a million for your explanation. I now understand how to extract the strings.

Basically, i can get an output from my command and perform a search followed by a f$element function to extract the string.

However, is there any command or method to extract by line number?

Let's say for example, i would like to extract only line 1 of textfile A and line 2 onwards of textfile B. Finally join them into a new textfile.

The way i see f$element is extracting strings by a seperator character or element.

Please kindly advice. Thank you!

Andrew
____________________________________________

Re: How to extract string from command output?

Andrew Yip — Thu, 12 Jan 2006 04:32:39 GMT

Hi Phil,

What are the workings beneath the 'tt'?
I can't run this in script mode. I'll have to execute it manually to obtain the output.

Andrew
____________________________________________

Re: How to extract string from command output?

Karl Rohwedder — Thu, 12 Jan 2006 05:00:13 GMT

The @ starts the commandfile TT, which is a logical name pointing to your terminal, but it allows for the /OUPUT qualifier.

There is a freeware utility called EXTRACT which allows to extract selectable record from files, see http://vms.process.com/scripts/fileserv/fileserv_search.exe?package=extract&description=&author=&system=Either&language=All&RD=&RM=&RY=

regards kalle

Re: How to extract string from command output?

Ian Miller. — Thu, 12 Jan 2006 05:30:01 GMT

TT is a logical name refering to your terminal.
$ @TT:

Is running a script from your terminal.

/OUTPUT redefines SYS$OUTPUT

The following will redirect output for one command then return to normal.

$ DEFINE/USER SYS$OUTPUT FILE.LIS
$ somecommandhere
Then open the file
$ OPEN HANDLE FILE.LIS
read the lines
$ READ HANDLE LINE
and process them.

Re: How to extract string from command output?

Andrew Yip — Thu, 12 Jan 2006 06:13:55 GMT

Hi Kalle,

Does the extract utility helps me in extracting particular lines from a textfile?

I'm unable to d/l the zip file.

Re: How to extract string from command output?

Karl Rohwedder — Thu, 12 Jan 2006 06:36:50 GMT

It allows specification of start/end records, start/end columns and can edit the extracted records (like F$EDIT, but more).

Here are the Examples from HELP:

2 examples
!Display the last 10 lines of Login.Com on the terminal
$ EXTRACT/TAIL=10 Login.Com /IDENTIFY

!Look at the first few lines of all Fortran source files
$ EXTRACT/HEAD=5 *.For

!Copy Test.Txt to Test.Dat, converting text into upper case
! and removing excess blanks.
$ EXTRACT/EDIT=(UPCASE,COMPRESS) Test.Txt/OUTPUT=Test.Dat

!Extract all but the first 10 and last 10 records of Test.Dat
$ EXTRACT Test.Dat/RECORDS=(START=11,END=-11) /OUTPUT=Test.Mid

!Get specific columns out of several files
$ EXTRACT/COLUMNS=(1:10,18:19,25,41:*) Test.*,[...]*.Tmp

I've added the ZIP file

regards Kalle

Re: How to extract string from command output?

Hein van den Heuvel — Thu, 12 Jan 2006 07:40:15 GMT

>> However, is there any command or method to extract by line number?
>> Let's say for example, i would like to extract only line 1 of textfile A and line 2 onwards of textfile B. Finally join them into a new textfile.

Sure, same loop through file principle, but keep a running count... in general. However, in the case of 1 or 2, I would just read it.
Untested example below.

Sounds like you'd better get that 'Programming in DCL book' and check out some examples, on your system or here in the forum.

However, since you are new to VMS/DCL I would suggest to learn PERL and/or AWK for file/line/text manipulation. You'll be able to use the skill on multiple platforms

$close/nolog file ! In case it was left open
$open file file-1
$n=6
$i=0
$loop:
$1=1+1
$read /end=not_found file record
$if i.lt.n then goto loop
$
$write sys$output "record ''n' = record"

Your question

$close/nolog file ! In case it was left open
$open file file-1
$read /end=not_found file record_1
$close file
$open file file-1
$read /end=not_found file record_2
$read /end=not_found file record_2
$close file
$open/write file file-3
$write file record_1 + record_2
$close file

to read record 123 in perl:

perl -ne "print if ($.== 123)"

Hein.

Re: How to extract string from command output?

Jan van den Ende — Thu, 12 Jan 2006 13:41:22 GMT

Andrew,

another wat to generate output from a command procedure, say ABCD.COM

$ @ABCD/OUTPUT= [p1] [p2] ...

Remember to put /out BEFORE any params.

hth

Proost.

Have one on me.

jpe

Re: How to extract string from command output?

Andrew Yip — Tue, 17 Jan 2006 08:21:36 GMT

I had extracted the numbers (free space) from the command output and made some logical comparison between them.

============================================
$ IF (MAINfreebytes .LES. INTfilesize) .OR. (VSMfreebytes .LES. PATfilesize)
$ THEN GOTO ERROR34
$ ELSE write temp "Free space check OK."
$ ENDIF
============================================

MAIN Memory free space: 2790400 bytes
VSM Memory free space: 59935744 bytes
Program file size: 91136 bytes
Pattern files size: 14043136 bytes
Insufficient tester memory space!

But the result was incorrect! This is so strange! I even explicitly defined them to be of integer type.

E.g.
$ INTfilesize = f$integer(f$element(4," ",record))

Can anyone advice on what is wrong here?
Thanks!

Andrew

Re: How to extract string from command output?

Andrew Yip — Tue, 17 Jan 2006 08:28:47 GMT

Sorry, i wasn't very clear in my previous post.

i was comparing the following:

$ IF (2790400 .LES. 91136) .AND. (59935744 .LES. 14043136)
$ THEN write sys$output "Insufficient tester memory space!"
$ ELSE write temp "Free space check OK."
$ ENDIF
============================================
Result: Insufficient tester memory space!

I was expecting to see "Free space check OK."