Slackware 14.2 CTRL-C & CTRL-U don't clear mistyped login or password fields
 

Recently installed Slackware 14.2 on my laptop after using Ubuntu for 2+ yrs. (Used Slackware from 1996-2015...) This version is running a /boot/vmlinuz-huge-4.9.31 kernel on an old 64bit Dell Inspiron 17R. I've noticed that on the plain Linux login screen, CTRL-U doesn't quite clear the field, but leaves one or two characters, and CTRL-C doesn't appear to work either. Thus, if I've mistyped either the login name or the password (which is quite common for me...), I have to wait for it to err out (thus, using one of the login attempts). Has anyone else experienced this? This has never happened for me in many past releases of Slackware...

CTRL-U works as expected to clear both the user name and password fields. BACKPSPACE also works in both cases. CTRL-C (interrupt) does not function as should be expected, as I think you do not what to interrupt/kill the login prompt...

Update on CTRL-U problem w/ Slackware 14.2
 

Upon further experimentation, I've discovered some interesting behavior. First of all, this seems to only be a problem on my one laptop (Dell Inspiron 17R); everything works as expected on my other laptop (Dell Inspiron 7548), also w/ Slackware 14.2 installed. Furthermore, the behavior described (erasing all but 1st char, ignoring CTRL-C) subsides after a failed login, but reappears after I either have a failed login attempt or do a CTRL-C. So, (possibly?) every other attempt is not as expected. Note that this happens from a plain black&white Linux terminal screen, not a window manager login screen. Anyway, I've never seen this performance. (I've installed and used many versions of Slackware from 1996-2015...) Weird. But, as I've said, seems to be specific to this one laptop. So in appears to be a device-dependent quirk that I can certainly live with...

The reason you don't always see it is because the bug is a race condition.

Fixed in the next util-linux release:
https://github.com/karelzak/util-lin...86e45dd57ddef3

After the initial prompt/response (such as a failed login attempt) /bin/login takes over from /sbin/agetty which is why you see different behaviour.


Pat has already patched util-linux in current to revert the problem commit, see:
https://www.linuxquestions.org/quest...2/#post5721585

I hadn't realised at the time that this issue was also in 14.2 as well as current.

Karel has taken a more fundamental approach to fixing this in the next util-linux than just reverting the problem commit, and I'm inclined to agree with his rip-it-out approach.