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 f210ea26c444607980d5de17ed7d4e62bb813631 | |
parent 8306568bd0b9d082c58ad897b4562ffe6822e585 | |
Author: Roberto E. Vargas Caballero <[email protected]> | |
Date: Thu, 24 Jul 2014 19:56:58 +0200 | |
Add info about Backspace and Delete to the FAQ | |
Diffstat: | |
M FAQ | 58 ++++++++++++++++++++++++++++++ | |
1 file changed, 58 insertions(+), 0 deletions(-) | |
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diff --git a/FAQ b/FAQ | |
t@@ -98,3 +98,61 @@ If you want to compile st for OpenBSD you have to remove -l… | |
st will compile without any loss of functionality, because all the functions a… | |
included in libc on this platform. | |
+## Backspace key does not work | |
+ | |
+This is an issue that was discussed in suckless mailing list | |
+<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). | |
+ | |
+ 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 | |
+ 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. | |
+ | |
+ [1] http://www.ibb.net/~anne/keyboard.html | |
+ [2] http://www.tldp.org/HOWTO/Keyboard-and-Console-HOWTO-5.html | |
+ |