tAdd info about Backspace and Delete to the FAQ - st - [fork] customized build … | |
git clone git://src.adamsgaard.dk/st | |
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--- | |
commit e8f3513bf4d953176ae932c5d7eb5c374b05a2a0 | |
parent f210ea26c444607980d5de17ed7d4e62bb813631 | |
Author: Wolfgang Corcoran-Mathe <[email protected]> | |
Date: Fri, 25 Jul 2014 13:32:29 -0400 | |
Add info about Backspace and Delete to the FAQ | |
Here is a modest attempt at cleaning it up a little bit. I changed a | |
few phrases that seemed awkward, but I think the content is the same. | |
-- | |
Wolfgang Corcoran-Mathe | |
Signed-off-by: Roberto E. Vargas Caballero <[email protected]> | |
Diffstat: | |
M FAQ | 87 +++++++++++++++--------------… | |
1 file changed, 43 insertions(+), 44 deletions(-) | |
--- | |
diff --git a/FAQ b/FAQ | |
t@@ -104,54 +104,53 @@ This is an issue that was discussed in suckless mailing … | |
<http://lists.suckless.org/dev/1404/20697.html>: | |
Well, I am going to comment why I want to change the behaviour | |
- of this key. When ascii was defined in 1968 communication | |
- with computers were done using punched cards, or hardcopy | |
- terminals (basically a typewritter machine connected with | |
- the computer using a serial port). Due to this, ascii defines | |
- DELETE as 7F, because in the puched cards, it means all the | |
- holes of the card punched, so it is a kind of 'phisical | |
- delete'. In the same way, BACKSPACE key was a non destructive | |
- back space, as in typewriter machines. So, if you wanted | |
- to delete a character, you had to BACKSPACE and then DELETE. | |
- Other use of BACKSPACE was accented characters, for example | |
- 'a BACKSPACE `'. The VT100 had no BACKSPACE key, it was | |
- generated using the CONTROL key as another control character | |
- (CONTROL key sets to 0 b7 b6 b5, so it converts H (code | |
- 0x48) into BACKSPACE (code 0x08)), but it had a DELETE key | |
- in a similar position where BACKSPACE key is located today | |
- in common PC keyboards. All the terminal emulators emulated | |
- correctly the difference between these keys, and backspace | |
- key generated a BACKSPACE (^H) and delete key generated a | |
- DELETE (^?). | |
- | |
- But the problem arised when Linus Torvald wrote Linux, and | |
- he did that the virtual terminal (the terminal emulator | |
- integrated in the kernel) returns a DELETE when backspace | |
- was pressed, due to the fact of the key in that position | |
- in VT100 was a delete key. This created a lot of problems | |
- (you can see it in [1] and [2]), and how Linux became the | |
- king, a lot of terminal emulators today generate a DELETE | |
- when backspace key is pressed in order to avoid problems | |
- with linux. It causes that the only way of generating a | |
- BACKSPACE in these systems is using CONTROL + H. I also | |
- think that emacs had an important point here because CONTROL | |
- + H prefix is used in emacs in some commands (help commands). | |
+ of this key. When ASCII was defined in 1968, communication | |
+ with computers was done using punched cards, or hardcopy | |
+ terminals (basically a typewriter machine connected with the | |
+ computer using a serial port). ASCII defines DELETE as 7F, | |
+ because, in punched-card terms, it means all the holes of the | |
+ card punched; it is thus a kind of 'physical delete'. In the | |
+ same way, the BACKSPACE key was a non-destructive backspace, | |
+ as on a typewriter. So, if you wanted to delete a character, | |
+ you had to BACKSPACE and then DELETE. Another use of BACKSPACE | |
+ was to type accented characters, for example 'a BACKSPACE `'. | |
+ The VT100 had no BACKSPACE key; it was generated using the | |
+ CONTROL key as another control character (CONTROL key sets to | |
+ 0 b7 b6 b5, so it converts H (code 0x48) into BACKSPACE (code | |
+ 0x08)), but it had a DELETE key in a similar position where | |
+ the BACKSPACE key is located today on common PC keyboards. | |
+ All the terminal emulators emulated the difference between | |
+ these keys correctly: the backspace key generated a BACKSPACE | |
+ (^H) and delete key generated a DELETE (^?). | |
+ | |
+ But a problem arose when Linus Torvalds wrote Linux. Unlike | |
+ earlier terminals, the Linux virtual terminal (the terminal | |
+ emulator integrated in the kernel) returned a DELETE when | |
+ backspace was pressed, due to the VT100 having a DELETE key in | |
+ the same position. This created a lot of problems (see [1] | |
+ and [2]). Since Linux has become the king, a lot of terminal | |
+ emulators today generate a DELETE when the backspace key is | |
+ pressed in order to avoid problems with Linux. The result is | |
+ that the only way of generating a BACKSPACE on these systems | |
+ is by using CONTROL + H. (I also think that emacs had an | |
+ important point here because the CONTROL + H prefix is used | |
+ in emacs in some commands (help commands).) | |
From point of view of the kernel, you can change the key | |
for deleting a previous character with stty erase. When you | |
- connect a real terminal into a machine you describe the | |
- type of terminal, so getty configure the correct value of | |
- stty erase for this terminal, but in the case of terminal | |
- emulators you don't have any getty that can set the correct | |
+ connect a real terminal into a machine you describe the type | |
+ of terminal, so getty configures the correct value of stty | |
+ erase for this terminal. In the case of terminal emulators, | |
+ however, you don't have any getty that can set the correct | |
value of stty erase, so you always get the default value. | |
- So it means that in case of changing the value of the | |
- backspace keyboard, you have to add a 'stty erase ^H' into | |
- your profile. Of course, other solution can be that st | |
- itself modify the value of stty erase. I have usually the | |
- inverse problem, when I connect with non Unix machines, and | |
- I have to press control + h to get a BACKSPACE, or the | |
- inverse, when a user connects to my unix machines from a | |
- different system with a correct backspace key. | |
+ For this reason, it is necessary to add 'stty erase ^H' to your | |
+ profile if you have changed the value of the backspace key. | |
+ Of course, another solution is for st itself to modify the | |
+ value of stty erase. I usually have the inverse problem: | |
+ when I connect to non-Unix machines, I have to press CONTROL + | |
+ h to get a BACKSPACE. The inverse problem occurs when a user | |
+ connects to my Unix machines from a different system with a | |
+ correct backspace key. | |
[1] http://www.ibb.net/~anne/keyboard.html | |
[2] http://www.tldp.org/HOWTO/Keyboard-and-Console-HOWTO-5.html |