topic Re: Backspace key taken as garbage during login in Operating System - HP-UX

Backspace key taken as garbage during login

Vibhor Kumar Agarwal — Thu, 05 Nov 2009 05:26:13 GMT

Hi,

Query about backspace key working funny on my HP systems (B.11.31 U ia64).

During login, if the user name is misspelled and then corrected by pressing the backspace key, the final name looks right on screen but login doesn't happen. This means that though the characters are deleted but the system takes backspace as some control character.

Not an serious or abnormal issue, but just wanted to check if there is an option (system configuration) to correct this.

Thanks

Re: Backspace key taken as garbage during login

Johnson Punniyalingam — Thu, 05 Nov 2009 05:43:41 GMT

I would like to Check TERM ?

echo $TERM

Re: Backspace key taken as garbage during login

Vibhor Kumar Agarwal — Thu, 05 Nov 2009 05:45:21 GMT

echo $TERM
xterm

Is the right terminal or shall i change it to vt100 or something?

Re: Backspace key taken as garbage during login

Johnson Punniyalingam — Thu, 05 Nov 2009 05:45:44 GMT

Once you are logged into the other computer, I believe the following command would do the job:

stty erase "^?"

which sets the erase character to "^?". See man stty for more info on "control characters" (and lots of other things too).

Re: Backspace key taken as garbage during login

Johnson Punniyalingam — Thu, 05 Nov 2009 05:47:00 GMT

>>is the right terminal or shall i change it to vt100 or something?

you can give a try :)

Re: Backspace key taken as garbage during login

Raj D. — Thu, 05 Nov 2009 06:01:35 GMT

Vibhor,
- Check # echo $TERM
- Also check the stty for backspace key by typeing:
# stty erase Enter

It will look like:
# stty erase ^?

Hth,
Raj.

Re: Backspace key taken as garbage during login

Vibhor Kumar Agarwal — Thu, 05 Nov 2009 06:39:11 GMT

Backspace character works perfect after login.

During login, on screen it works as perfect by deleting the previous character, but the system doesn't take it.

How do i set the TERM variable for the system so that it's available for next logins?

Re: Backspace key taken as garbage during login

Johnson Punniyalingam — Thu, 05 Nov 2009 06:50:43 GMT

>>How do i set the TERM variable for the system so that it's available for next logins?<<

.profile

Then type in

stty erase ^?

Re: Backspace key taken as garbage during login

Venkatesh BL — Thu, 05 Nov 2009 08:01:57 GMT

The stuff inside '$HOME/.profile' will be executed only after a successful login. So, I don't think putting 'stty erase' there would make any difference.

I think this has something to do with the default shell that is invoked by the 'login' command.

Re: Backspace key taken as garbage during login

melvyn burnard — Thu, 05 Nov 2009 08:27:35 GMT

You don't change anything.
WHen logging in, the backspace key will NOT work, use the # key to backspace one character at a time, or use @ to erase the line and start again.
This is why these characters are NOT allowed as part of your login name or password

Re: Backspace key taken as garbage during login

Dennis Handly — Thu, 05 Nov 2009 11:26:38 GMT

Re: Backspace key taken as garbage during login

Tingli — Thu, 05 Nov 2009 21:32:58 GMT

If you use Putty, you can try this.

In Putty, go to Terminal -> Keyboard.

You will see the "The Backspace key", pickup control-?(127) and see how it works.

Re: Backspace key taken as garbage during login

Bill Hassell — Fri, 06 Nov 2009 03:12:04 GMT

This is not a problem with $TERM or Putty or profiles. This is a feature of the tty driver, much like the default baud rate for a serial port (300 baud). It's hard coded to the same value it was in the 1980's. Here are the details:

The default settings for the terminal driver is @=delete-line and #=backspace. Every HP-UX system since the 1980's has used these defaults. The reason is historic as these characters were used with hardcopy terminals where a backspace key cannot erase the ink on the paper. Today, they get in the way and your standard /etc/profile will have two stty statements that set the 'normal' characters for delete-line and backspace. However, /etc/profile does not run until after you login so it does not affect the login and passwd programs.

If you are running 10.20 or any version of 11.xx you can fix this using the ttyconf device file. Do this once while you are running:

stty erase "^H" kill "^U" < /dev/ttyconf

and now backspace will work for login, and @ can be used in a password. It will take effect for all new logins except for the console (which is opened at bootup). To set the console login, you'll need to create a small startup script the runs early in the boot process.

Re: Backspace key taken as garbage during login

Vibhor Kumar Agarwal — Mon, 16 Nov 2009 11:16:51 GMT

Thanks everybody for your inputs.

Re: Backspace key taken as garbage during login

Sp4admin — Mon, 16 Nov 2009 21:52:05 GMT

You need to check the term type. Type "env" and see what the term value is set to. then type TERM=vt100 or hpterm. If that doesn't work then do stty erase ^?.

sp,

Re: Backspace key taken as garbage during login

OldSchool — Mon, 16 Nov 2009 22:52:53 GMT

"You need to check the term type. Type "env" and see what the term value is set to. then type TERM=vt100 or hpterm. If that doesn't work then do stty erase ^?."

that DOESN'T apply until AFTER login, whch the OP isn't referring to

Re: Backspace key taken as garbage during login

Kavitha_K — Wed, 18 Nov 2009 14:56:44 GMT

Hi,
On a 11.31 ia64; I am seeing this same issue of backspace causing garbled login credentials.
I used following to get backspace to work even at login, as suggested above;
stty erase "^H" kill "^U" < /dev/ttyconf

But, doesn't ^H translate to shift+backspace ?

So, on the same lines, I tried doing;
stty erase "^?" kill "^U" < /dev/ttyconf

It succeeded in setting;
stty < /dev/ttyconf
erase = DEL; kill = ^U;
swtch ;

But, this doesn't resolve the issue of garbled input at login if I use backspace now!

Any clue?

Re: Backspace key taken as garbage during login

Bill Hassell — Fri, 20 Nov 2009 03:08:24 GMT

> On a 11.31 ia64; I am seeing this same issue of backspace causing garbled login credentials.

I don't understand the term "login credentails". Are you talking about login and password? When you say garbled, do you mean that typing abc produces a string like Cgfc$3(55?

> I used following to get backspace to work even at login, as suggested above;
stty erase "^H" kill "^U" < /dev/ttyconf
> But, doesn't ^H translate to shift+backspace ?

No, the nomenclature "^H" translates to control-H and on a normal keyboard, this produces the backspace character (see man ascii). DEL is the delete character which matches the "^?" stty setting.

> So, on the same lines, I tried doing;
stty erase "^?" kill "^U" < /dev/ttyconf
>
> It succeeded in setting;
> stty < /dev/ttyconf
> erase = DEL; kill = ^U;
> swtch ;

And that is correct, but not what most users want. Use the command:

stty erase "^H" < /dev/ttyconf

Then use the backspace key. Note that all of this applies to terminal sessions such as xterm, hpterm and dtterm. If you are filling a special form in Xwindows, then ttyconf probably won't help.

Re: Backspace key taken as garbage during login

Aneesh Mohan — Fri, 20 Nov 2009 07:49:46 GMT

see the solution here

stty kill '^X' intr '^C' werase '^W' erase '^?'

http://forums13.itrc.hp.com/service/forums/questionanswer.do?threadId=1387943

Aneesh

Re: Backspace key taken as garbage during login

Dennis Handly — Sat, 21 Nov 2009 18:49:17 GMT

>Bill: the nomenclature "^H" translates to control-H and on a normal keyboard, this produces the backspace character. DEL is the delete character which matches the "^?" stty setting. ...
>And that is correct, but not what most users want.

Unfortunately some new fangled windows and other terminal emulator use DEL and not control-H.
But since I use both interchangeably and I'm been using computers a long time and I'm used to the DEL key doing nothing, I use ^H. And ^X for kill.