topic Re: Clear screen in Operating System - OpenVMS

Clear screen

jpaulino05 — Tue, 01 Aug 2006 19:40:09 GMT

There is any way to clear the screen in openVMS?

Thks in advanced

Re: Clear screen

Thomas Ritter — Tue, 01 Aug 2006 19:55:42 GMT

Create a command procedure with

$ ESC[0,7] = 27
$ WRITE SYS$OUTPUT "''ESC'[2J''ESC'[1;1H"

Set a symbol to run the procedure.

Re: Clear screen

David B Sneddon — Tue, 01 Aug 2006 20:23:10 GMT

$ TYPE/PAGE NLA0:

Dave

Re: Clear screen

Thomas Ritter — Tue, 01 Aug 2006 21:13:30 GMT

Thanks David :)

Re: Clear screen

Alanjones_1 — Tue, 01 Aug 2006 22:31:46 GMT

Dear David

What is mean by NLA0: is it default device specification or ...?

Regards
Balamurali

Re: Clear screen

David B Sneddon — Tue, 01 Aug 2006 22:39:35 GMT

NLA0: is the null device. Useful for testing
certain things. Writes always succeed and
reads always return end-of-file. It is a
bit-bucket, black hole, somewhere to send
things when you don't want the output.

e.g. $ show system/output=nla0:

Dave.

Re: Clear screen

Ian Miller. — Wed, 02 Aug 2006 04:01:25 GMT

Note that the NLA0: device is good for fast backups when a restore is not required :-)

Re: Clear screen

Bart Zorn_1 — Wed, 02 Aug 2006 06:10:53 GMT

Thomas Ritter wrote:

> Create a command procedure with
>
>$ ESC[0,7] = 27
>$ WRITE SYS$OUTPUT "''ESC'[2J''ESC'[1;1H"
>
>Set a symbol to run the procedure.

I would prefer:

$ WRITE SYS$OUTPUT ESC, "[H", ESC, "[J"

Note that there is a difference between this method and TYPE/PAGE NL:

TYPE/PAGE NL: leaves the cursor at the first line of your terminal, whereas the escape sequence puts you on the second line!

Regards,

Bart Zorn

Re: Clear screen

Ian Miller. — Wed, 02 Aug 2006 06:54:35 GMT

The other key difference between TYPE/PAGE and WRITE is that the former runs an image but the latter does not.

Re: Clear screen

John Gillings — Wed, 02 Aug 2006 22:01:26 GMT

The biggest difference is in device independence (at least partial). Sending an explicit escape sequence assumes an ANSI (VT100) compatible terminal.

TYPE/PAGE NL: determines the terminal type (as set with SET TERMINAL) and issues the "correct" escape sequence to clear the page (assuming your device type is set correctly).

On the other hand, the WRITE command will work on an ANSI terminal regardless of the terminal type set.

Re: Clear screen

Chinraj Rajasekaran — Thu, 03 Aug 2006 02:02:37 GMT

Hi,

Normally i use these commands to clear screen in VMS.

$ set terminal /width=132
(or)
$ set terminal /width=80

regards
Raj

Re: Clear screen

Robert Atkinson — Thu, 03 Aug 2006 03:03:55 GMT

Our version of 'clear screen' attached, with about 8 billion escape sequences.....ok, slight exageration there, but don't ask me what they all do, as they've been built up over some years.

Use with '$ TYPE CLS.TXT'.

Rob.

Re: Clear screen

Jan van den Ende — Tue, 13 Aug 2024 10:34:30 GMT

Bart.

>$ ESC[0,7] = 27
>$ WRITE SYS$OUTPUT "''ESC'[2J''ESC'[1;1H"
>
>Set a symbol to run the procedure.

I would prefer:

$ WRITE SYS$OUTPUT ESC, "[H", ESC, "[J"

Note that there is a difference between this method and TYPE/PAGE NL:

TYPE/PAGE NL: leaves the cursor at the first line of your terminal, whereas the escape sequence puts you on the second line!

That is of your own doing!

After your sequence, the write will generate an implicit CrLf, puuting you on the next (ie 2nd) line.

However, the ''ESC'[1;1H is a cursor positioning which (at least, as the last element of the sequence) will overrule the need for the added CrLf.

jpaulino05,

as you are new, please review

~~http://forums1.itrc.hp.com/service/forums/helptips.do?#33~~

Proost.

Have one on me.

jpe

[Moderator edit: The above link is no longer valid.]

Re: Clear screen

Bart Zorn_1 — Fri, 04 Aug 2006 01:18:13 GMT

Jan,

Did you try it?

DCL knows nothing of escape sequences, so you get the CR/LF anyway. And,"esc>[H" is short for "[1;1H"

Regards,

Bart

Re: Clear screen

Steven Schweda — Fri, 04 Aug 2006 01:47:49 GMT

I worry about supplying escape sequences when
"the screen" is no better defined than this,
but if you don't like the carriage control
from WRITE, you might try something like:

$ esc = " "
$ esc[ 0, 8] = 27
$ esc_seq = esc+ "[2J"+ esc+ "[H"
$ read /error = err1 /prompt = "''esc_seq'" /time_out = 0 sys$command line
$ err1:

Re: Clear screen

Jan van den Ende — Fri, 04 Aug 2006 11:44:36 GMT

Bart,

I tried, and YOU are right!

Amazing. I have been using that for sooo many years now, and never knew, nor noticed.

Thanks for another bit of education!

Proost.

Have one on me.

jpe

Re: Clear screen

Bart Zorn_1 — Mon, 07 Aug 2006 01:57:34 GMT

Jan,

:-)

Steven,

Yes, the READ command can do it without the CR/LF. Unfortunately, the construct is a bit tedious.

Regards,

Bart

Re: Clear screen

Steven Schweda — Mon, 07 Aug 2006 10:30:29 GMT

> [...] the construct is a bit tedious.

That's why I put it into a command procedure
instead of typing it interactively.

Some people will complain if they're hanged
with a new rope.

Re: Clear screen

Bart Zorn_1 — Tue, 08 Aug 2006 01:36:05 GMT

> That's why I put it into a command procedure
instead of typing it interactively.

Sure, but then your advantage over an image activation decreases!

Bart