topic Re: Perl and awk result to a symbol/logical? in Operating System - OpenVMS

Perl and awk result to a symbol/logical?

roose — Wed, 17 Feb 2010 05:15:51 GMT

Hi Folks,

Is it possible to assign the result of a perl or awk command to a VMS symbol or logical? I'm initially trying to do some decimal computation and would like to use either perl or awk without piping the output to a file, then manipulate later on the value using my DCL script.

Thanks.

Re: Perl and awk result to a symbol/logical?

Joseph Huber_1 — Wed, 17 Feb 2010 07:22:42 GMT

Get the some VMS:: packages for perl, then there is the setsym() function available.
Example:

# convert a Unix style path to VMS filespec using PERL rules
# argument 1 is the unix path (in string quotes to preserve case)
# output is in global DCL symbol VMS_FILENAME
# Author: Joseph Huber
use VMS::Filespec;
use VMS::DCLsym;
my $f = shift ;
my $x = vmsify($f) ;
#print $x;
$handle = new VMS::DCLsym;
$handle->setsym('VMS_FILENAME',$x,'GLOBAL') or die "Can't create symbol: $!\n";

Re: Perl and awk result to a symbol/logical?

roose — Wed, 17 Feb 2010 08:03:35 GMT

Thanks Joseph for the quick reply. I was thinking more initially of a one liner command, and I have been able to get one for perl:

$ value1 = "400"
$ value2 = "375.56"
$ perl -e "$ENV{myvalue} = sprintf(""%3.2f"",(400 - 375.56) / 375.56 * 100)"
$ show logi myvalue
"MYVALUE" = "6.51" (LNM$PROCESS_TABLE)

Now, if I would like to do such a thing using awk, how can I export awk's one liner result to a VMS logical/symbol?

Re: Perl and awk result to a symbol/logical?

labadie_1 — Wed, 17 Feb 2010 08:15:55 GMT

For using awk, see the procedure typlog on dcl.openvms.org

http://dcl.openvms.org/stories.php?story=08/12/04/2298229

Instead of doing
system ("type/tail " $NF ) }

you can do
system ("def/job mylogical $NF")
or something similar.

Re: Perl and awk result to a symbol/logical?

H.Becker — Wed, 17 Feb 2010 11:34:03 GMT

If you have gnv installed you can do something simple like:

$ mc SYS$COMMON:[GNV.bin]bash. -c "x=`dcl sh sys/noproc/full` && dcl def/job x ""\""$x\""""
$ sh log x
"X" = "OpenVMS V8.3 on node BREZN 17-FEB-2010 11:27:25.03 Uptime 2 01:22:16. COMPAQ AlphaServer DS20E 833 MH." (LNM$JOB_84613700)
$

In case it is not so obvious in the used font, here: there are backticks used to assign the value to x.

But with gnv then you get dcl.c, the source code of this wrapper and then you can easily hack a:

$ mc []symfromdcl sys show sys/noproc/full
$ sh symb sys
SYS = "OpenVMS V8.3 on node BREZN 17-FEB-2010 11:27:28.47 Uptime 2 01:22:19. COMPAQ AlphaServer DS20E 833 MH."
$

(Yes, there is a \n after each output line in the symbol.)

Re: Perl and awk result to a symbol/logical?

Hein van den Heuvel — Wed, 17 Feb 2010 14:37:11 GMT

Back to Perl,

Be sure to check out the documentation
on: CLISYM_[LOCAL] and PERL_ENV_TABLES.
in: http://perldoc.perl.org/perlvms.html

You may also want to google for DCLsym.
For example:

http://www.ryerson.ca/perl/manual/vms/lib/DCLsym.html'

Regards,
Hein.

Re: Perl and awk result to a symbol/logical?

Craig A Berry — Wed, 17 Feb 2010 15:30:20 GMT

A couple more follow-ups on a Perl solution involving DCL symbols (though there's nothing wrong with using logical names if that works for you).

There is no reason, if you have Perl, to acquire extra modules in this case; VMS::DCLsym has been part of the core distribution for eons.

Although not much has changed recently, somewhat more current docs than what Hein points to are available here:

http://search.cpan.org/~dapm/perl-5.10.1/vms/ext/DCLsym/DCLsym.pm

There is nothing about the use of modules that precludes one-liners, though the command line can get on the long side:

$ perl -"MVMS::DCLsym" -e "$h=new VMS::DCLsym; $h->setsym('myvalue',sprintf(""%3.2f"",(400-375.56)/375.56*100),'GLOBAL');"
$ show symbol myvalue
MYVALUE == "6.51"

The perl command above shows up as wrapped here but fits on one line in 132-wide mode.

Re: Perl and awk result to a symbol/logical?

labadie_1 — Wed, 17 Feb 2010 15:47:01 GMT

Sorry, I did a typo, the correct code looks like

system ("def/job mylogical " $NF )

Re: Perl and awk result to a symbol/logical?

John Gillings — Wed, 17 Feb 2010 21:03:17 GMT

A rather ugly and expensive, but general way to get a one line result of any command into a logical name, using PIPE:

$ PIPE perl -e "sprintf(""%3.2f"",(400 - 375.56) / 375.56 * 100)" | -
(READ SYS$PIPE v ; DEFINE/JOB/NOLOG myvalue &v)
$ show logi myvalue
"MYVALUE" = "6.51" (LNM$JOB_82874EC0)

Not the kind of thing you'd want to do in a tight loop, but the benefit is that it works for anything.

An even more general mechanism in a DCL procedure is to pipe the output of one part into another invocation of the same procedure, with some mechanism for choosing a different path.

(note that some of the other suggestions look like they involve creating a process, so are probably a similar expense as the above PIPE command).

Re: Perl and awk result to a symbol/logical?

Joseph Huber_1 — Thu, 18 Feb 2010 09:10:51 GMT

>>
(note that some of the other suggestions look like they involve creating a process, so are probably a similar expense as the above PIPE command).<<

But the perl VMS::setsym() does only the one image invocation (Perl), and not 2 subprocesses like the pipe solutions.
And since the job logical table space is rather small, one should take care to deassign the logical after use!

Re: Perl and awk result to a symbol/logical?

labadie_1 — Thu, 18 Feb 2010 09:38:00 GMT

>>>And since the job logical table space is rather small, one should take care to deassign the logical after use!

So

$ mysymb = f$trnlnm("mylogical","lnm$job")
$ deas/job mylogical

Re: Perl and awk result to a symbol/logical?

Joseph Huber_1 — Thu, 18 Feb 2010 10:45:47 GMT

One addition:
when using the perl $ENV{myvalue} method, don't blindly expect to have the logical MYVALUE defined, it could well be a global DCL symbol (or nothing at all if perl defined a local DCL symbol).
To make sure perl creates the right entity independent of the installation or system setup:

$ define/user PERL_ENV_TABLES CLISYM_GLOBAL
or
$ define/user PERL_ENV_TABLES LNM$FILE_DEV
before invoking perl.
Then $ENV() generates DCL symbols resp. logical names.

Re: Perl and awk result to a symbol/logical?

Joseph Huber_1 — Thu, 18 Feb 2010 10:54:03 GMT

and for results needed only inside a DCL procedure, a local symbol is appropriate:

define/user PERL_ENV_TABLES CLISYM_LOCAL
perl -e "$ENV{result} = sprintf(""testing result"")"
sh sym result
RESULT = "testing result"