[CentOS] Backspace key is sending Delete after update to 4.4 (tcsh issue?)

John Summerfied debian at herakles.homelinux.org
Mon Sep 4 01:35:52 UTC 2006

Rodrigo Barbosa wrote:
> Hash: SHA1
> On Sun, Sep 03, 2006 at 08:11:18AM +0800, John Summerfield wrote:
>>The correct behaviour for the backspace key is to send the BS character, 
>>0x08 aka ^H.
>>^? I suspect is the DEL character, 0x7f, which is unprintable (or prints 
>>as a space). I would expect the Delete key to produce a DEL character.
> The correct behaviour for who ? For many platforms (Sun is the first
> one that comes to memory), the correct backspace char was always
> ^?

By definition of the American National Standards Institute.

> At least here, for me, DEL shows are ^[[3~ (ANSI code ?!?).

Those are character interpretations, not the underlying codes. They are 
ANSI control sequences for controlling terminals. I suspect they 
originated with the Digital Equipment Corporation, possibly with its 
VT100 glass teletypes.

The backspace character's original purpose was to tell a 
printer-keyboard to back space one position, so the next chracter would 
overtype the previous: it was exactly opposite to a space.

The DEL character is also known as RUBOUT. Why?

In the olden days, we used paper tape. Nobody wanted to throw out, or 
rekey, a roll of paper tape because of a small error. How do we fix a 
wrong character/ We rub it out. We punch holes across the tape, and so 
the value 0x7f (remember, ASCII is a seven-bit code). A program reading 
data from paper tape had to recongise special control characters; one of 
them was DEL, which it simply dropped.

> Yes, on ASCII, DEL is 7F and BS is 08. But remember the issue here are
> not charsets, but console control codes, which usually are the same, but
> not always.
> The definition is kind of iffy, but on the console_codes manpage
> it states that, for Linux BS should indeed produce ^H. But lets remember
> that is Linux specific, and might not be true to many other platforms.



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