Clear screen

[jpaulino05]

There is any way to clear the screen in openVMS?

Thks in advanced

[Thomas Ritter]

Create a command procedure with

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

Set a symbol to run the procedure.

[David B Sneddon]

$ TYPE/PAGE NLA0:

Dave

[Thomas Ritter]

Thanks David :)

[Alanjones_1]

Dear David

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

Regards
Balamurali

[David B Sneddon]

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.

[Ian Miller.]

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

[Bart Zorn_1]

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

[Ian Miller.]

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

[John Gillings]

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.

[Chinraj Rajasekaran]

Hi,

Normally i use these commands to clear screen in VMS.

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

regards
Raj

[Robert Atkinson]

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.

[Jan van den Ende]

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.]

[Bart Zorn_1]

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

[Steven Schweda]

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:

[Jan van den Ende]

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

[Bart Zorn_1]

Jan,

:-)

Steven,

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

Regards,

Bart

[Steven Schweda]

> [...] 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.

[Bart Zorn_1]

> 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