Re: [ptxdist] Backspace not working in terminal (using ssh)

["Dold, Wolfram" <Wolfram.Dold@allegion.com>]

On Tue, 2019-03-19 at 17:42 +0000, Ian Abbott wrote:
> On 19/03/2019 12:33, Dold, Wolfram wrote:
> > Hi Ian,
> > On Tue, 2019-03-19 at 12:06 +0000, Ian Abbott wrote:
> > > On 19/03/2019 09:17, Dold, Wolfram wrote:
> > > > Hi there,
> > > > when we connect via ssh to our embedded device, the backspace key does not work.
> > > > During the analysis we found out that the passage
> > > > 
> > > > # This fixes the backspace when telnetting in.
> > > > if [ "$TERM" != "linux" ]; then
> > > >           stty erase ^H
> > > > fi
> > > > 
> > > > from the file '/etc/profile' contained in ptxdist.
> > > > 
> > > > Now I want to ask, how best to fix this behavior?
> > > > Can the passage simply be omitted? (At least the comment lets me assume that, because there 'telnet' is
> > > > mentioned
> > > > and
> > > > that is no longer necessarily state of the art).
> > > > Or does omitting it lead to other unwanted side effects?
> > > > 
> > > > Any help would be appreciated.
> > > > 
> > > 
> > > Code can interpret input characters in various ways independently of the
> > > stty settings.  For example, if the "Command Line Editing" feature is
> > > enabled in the Busybox configuration, the Busybox "ash" and "hush"
> > > shells' interactive line editing will handle both ASCII DEL and ASCII BS
> > >    as a "backspace" operation.  This can be enabled in the PTXdist
> > > menuconfig via:
> > > 
> > > Shell & Console Tools --->
> > >     -*- busybox --->
> > >         Settings --->
> > >           [*] Command Line Editing
> > > 
> > > This sets "PTXCONF_BUSYBOX_FEATURE_EDITING=y" in the ptxconfig file.
> > > 
> > 
> > The feature is already enabled.
> > But it does not work for me. It only works when I delete the stty command from /etc/profile,
> > 
> > > If you are using Bash or some other other program with READLINE support,
> > > I think it handles ASCII BS and ASCII DEL similarly to Busybox's command
> > > line editing feature.
> > 
> > We do not use bash, we use the busybox shell.
> 
> Just for comparison, I'm using the busybox "ash" shell.  (There are two 
> shells in Busybox - "ash" and "hush".)
> 
> My SSH client is set to send ASCII DEL when the backspace is pressed, 
> and sets TERM="xterm" or TERM="xterm-256color".  The stty command on my 
> target system shows "erase ^H".
> 
> Both the backspace key (which sends ASCII DEL) and the CTRL-H sequence 
> (which sends ASCII BS) result in a backspace operation on the ash 
> command line.
> 
> If I run a command that doesn't do any fancy line editing, such as:
> 
>    od -c
> 
> then the ASCII DEL characters get passed through to standard input and 
> the ASCII BS characters erase the previous characters (as per the stty 
> erase ^H setting).
> 
> If I change the stty setting:
> 
>    stty erase '^?'
> 
> then both ASCII DEL and ASCII BS result in a backspace operation on the 
> ash command line, but for commands that do not do any fancy line 
> editing, the ASCII BS is passed through to standard input and the ASCII 
> DEL erases the previous character as per the stty erase '^?' setting.
> 
> So in summary, the PTXCONF_BUSYBOX_FEATURE_EDITING option seems to work 
> for me, at least in the "ash" shell.  (I haven't tried the "hush" shell.)
> 
> I am using BusyBox 1.29.3 from PTXdist 2019.03.0.
> 
Sorry, I didn't describe the problem detailed enough:
When I type in the shell, everything works as you described it. 
The problem that the backspace key doesn't work occurs when we 
use the busybox-read function from a shell script.

We are using ash from busybox.
We are using BusyBox v1.29.3 from ptxdist 2019.03.1

Sorry again for the miscommunication.
-- 
Regards, Wolfram
 

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