How to disable Ctrl and Alt keys? (and maybe sysrq)
 

I'm working with slackware, and trying to disable Ctrl and Alt keys. I am _not_ using X. The application I'm building is a prototype electronic voting machine. (yes, we have a paper trail! every state of the voting pannel is printed out in a hex-barcode on a grocery-style printer) We need to elminate most functionality of the keyboard while voting is in progress. I was wondering which way would be ideal (scancode or keymaps) and I'm pritty new with linux, having only about 5 months of experience. I'm fairly computer-able though, and a second year computer science major now. Any help or advice would be great, thanks for help! :)

-Justin Perkins:newbie:

What window manager do you use ?

If you're under X you can try using xmodmap (take a look at it's man page).

wow, quick to the punch, I realized the second I posted that I didn't state "not in X" just in normal console or whatever the cmd line version is. (normal for me, since I have started using linux, I havn't used the gui nearly ever)

-Justin Perkins

take a keymap from /usr/share/kbd/keymaps/i386 directory then gunzip it and edit it to get
rid of any key you want, gzip it and make sure your /etc/rc.d/rc.keymap load it at boot

So I went looking for that /etc/rc.d/rc.keymap file which should load the keymap (right?) and all thats in the directory is: rc.0 rc.6 rc.M rc.acpid rc.local rc.serial rc.sysvinit rc.4 rc.K rc.S rc.hotplug rc.modules rc.syslog rc.udev
I'm using version 2.4.26 (gcc version 3.3.4) and I stripped down the size of the install as much as possible (it's < 60megs now) because we're using compact flash plugged into the IDE channel as a HD and a VIA-EPIA mobo (eden processor) which means it has (count em!) zero moving parts which is nifty... but I realize it isn't a great developing machine because so many utils are stripped out. I will reinstall (more fully) on a second machine tomorrow and see if I can use the previous advice to create the file I need and import it to the mini-install ... thanks for the quick help! :)

The rc.keymap just has to contains a few lines and be executable :

[edit]
Did you install kbd package ?

Doubtful on the kbd package. Do I need it? :) (clearly hehe) anyways, I stripped down the install: as many questions going through the step by step newb install script as I could I answered no to. If I need that ok, but, how is my keyboard mapped even if I didn't load that? I mean I don't even have the loadkeys util (so where is the keyboard map coming from?)

-Justin Perkins

update: I made a full install of slackware 10.0 with only the X and gnome stuff out... I installed the kbd package, and verified it was installed with pkgtool but I still don't have this rc.keymap file. Should I create it from your example? Shouldn't I just be able to edit the qwerty default keymapfile?

With no clue- Justin Perkins

Edit /etc/inittab and find the line that reads

# What to do at the "Three Finger Salute".
ca::ctrlaltdel:/sbin/shutdown -t5 -r now


Edit it to your likings...:)

hehe, good call, but: I was really trying to accually disable ctrl and alt keys themselves (which would have the effect of making the "three finger salute" un-doable but also disalow a slew of other meta cmds. . . Ctrl-C comes to mind and Alt-codes that would allow people messing around to screw stuff up. (input some of the symbols we are using for barcode-scanner which we need to be 'uncreatable' via the keyboard) so thanks, but no cigar, your leap of logic was slightly off, but makes perfect sense, thanx :)

-Justin PErkins

I have solved this problem to my satisfaction. I used the following advice to edit the keymap I want. I added a little shell script to my /etc/rc.d/rc.local file (last script to be run before login) that asks me which loadkeys file to load. This is how you edit that loadkey-file:

To modify the Control and Alt keys you can do the following:

At the root prompt:
(you must be root to do this)

# dumpkeys > keylist.txt

# vi keylist.txt

find the line that says "keycode 29 = Control" and edit it by pressing 'i'

you can change this to a number of values but leaving it blank will disable it.

do the same thing for:
keycode 56 and keycode 97 (or whatever keys you want to disable)

then save the file by typing ':wq!'

then type:

# loadkeys keylist.txt

which will add the edits you did.

Well congratulations on that... glad to see you worked it out. Thanks for making sure to put it here, too many people *don't* do that, so even if someone with the same questions does search, it doesn't do them any good.

Disable Function keys
 

Hi all

i'm trying to diable Functions Keys, both Alt , Ctrl, Delete, and backspace keys. using X
using xmodmap but not working propery....please give ur professional ideaz...
i'm trying like this.
xmodmap -e 'clear Lock' \
-e 'keycode 0x42 = Control_L' \
-e 'add Control = Control_L' \
-e 'keycode 0x16 = BackSpace' \
-e 'keycode 0x6B = Delete' \
-e 'keycode 0x40 = ALT-L' \
-e 'keycode 0x7d = ALT-R' \
-e 'keycode 37 = F13' \
-e 'keycode 64 = F13' \
-e 'keycode 70 = F13' \
-e 'keycode 95 = F13' \
-e 'keycode 109 = F13' \
-e 'keycode 113 = F13'


is it seems to perfect ?