11–20 of 76 posts
My favorite signal surprise was running nginx and/or httpd in the foreground and wondering why on earth it quit whenver i resized the window. Turns out, they use SIGWINCH (which is sent on WINdow CHange) for graceful shutdown. It's a silly, silly problem.
That’s … that’s even worse than people who send errors with an HTTP 200 response code.
> Another common extension is to use what is sometimes called a double Ctrl-C pattern. The first time the user hits Ctrl-C, you attempt to shut down the database cleanly, but the second time you encounter it, you give up and exit immediately. This is a terrible behavior, because users tend to hit Ctrl-C multiple times without intending anything different than on a single hit (not to mention bouncing key mechanics and…
> Unclean exits should be reserved for SIGQUIT (Ctrl-\) and SIGKILL (by definition). I don't know how it works on your keyboard but on french layout, Ctrl-\ is a two-hands, three-fingers, very unpleasant on the wrist, keyboard shortcut. Not a chance I'd use that for such a common operation.
> Another common extension is to use what is sometimes called a double Ctrl-C pattern. The first time the user hits Ctrl-C, you attempt to shut down the database cleanly, but the second time you encounter it, you give up and exit immediately. This is a terrible behavior, because users tend to hit Ctrl-C multiple times without intending anything different than on a single hit (not to mention bouncing key mechanics and…
> Unclean exits should be reserved for SIGQUIT (Ctrl-\) and SIGKILL (by definition). I don't know how it works on your keyboard but on french layout, Ctrl-\ is a two-hands, three-fingers, very unpleasant on the wrist, keyboard shortcut. Not a chance I'd use that for such a common operation.
> Another common extension is to use what is sometimes called a double Ctrl-C pattern. The first time the user hits Ctrl-C, you attempt to shut down the database cleanly, but the second time you encounter it, you give up and exit immediately. This is a terrible behavior, because users tend to hit Ctrl-C multiple times without intending anything different than on a single hit (not to mention bouncing key mechanics and…
> Unclean exits should be reserved for SIGQUIT (Ctrl-\) and SIGKILL (by definition). I don't know how it works on your keyboard but on french layout, Ctrl-\ is a two-hands, three-fingers, very unpleasant on the wrist, keyboard shortcut. Not a chance I'd use that for such a common operation.
Probably because Linux doesn't implement it. Worst mistake Linus ever made.
Also, it talks about self-pipe but doesn't mention that self-socket is much better since you can't select on a pipe.
Earlier quoted context omitted.
> Unclean exits should be reserved for SIGQUIT (Ctrl-\) and SIGKILL (by definition). I don't know how it works on your keyboard but on french layout, Ctrl-\ is a two-hands, three-fingers, very unpleasant on the wrist, keyboard shortcut. Not a chance I'd use that for such a common operation.
While on UK keyboards it's the opposite "problem" - the left Ctrl key and the \ key are right next to each other (making it potentially a one-finger operation), which is the opposite of how a US keyboard is laid out (where Ctrl-\ was presumably intended to need to be a two-handed, two-finger operation).
Earlier quoted context omitted.
> Unclean exits should be reserved for SIGQUIT (Ctrl-\) and SIGKILL (by definition). I don't know how it works on your keyboard but on french layout, Ctrl-\ is a two-hands, three-fingers, very unpleasant on the wrist, keyboard shortcut. Not a chance I'd use that for such a common operation.
The byte that sends SIGQUIT is very much configurable with stty quit ^X , but unfortunately X has to be a-z or one of \]^_ (that is, 0x41 through 0x5F except 0x5B = [ which would conflict with other uses of ESC = ^[ = 0x1B) because of how the Ctrl modifier traditionally works. Looking at a map of AZERTY, I don’t see any good options, but you may still want to experiment.
Earlier quoted context omitted.
> Unclean exits should be reserved for SIGQUIT (Ctrl-\) and SIGKILL (by definition). I don't know how it works on your keyboard but on french layout, Ctrl-\ is a two-hands, three-fingers, very unpleasant on the wrist, keyboard shortcut. Not a chance I'd use that for such a common operation.
I think the point is that it is not to be a common operation.
I recently wrote a little data transfer service in python that runs in ECS. When developing it locally it was easy to handle SIGINT: try write a batch, except KeyboardInterrupt, if caught mark the transfer as incomplete and finally commit the change and shut down. But there’s no exception in python to catch for a SIGTERM, which is what ECS and other service mangers send when it’s time to shut down. So I had to add a…
from signal import SIGTERM, raise_signal, signal
import sys # for excepthook
class Terminate(BaseException):
pass
def _excepthook(type, value, traceback):
if not issubclass(type, Terminate):
return _prevhook(type, value, traceback)
# If a Terminate went unhandled, make sure we are killed
# by SIGTERM as far as wait(2) and friends are concerned.
signal(SIGTERM, _prevterm)
raise_signal(SIGTERM)
_prevhook, sys.excepthook = sys.excepthook, _excepthook
def terminate(signo=SIGTERM, frame=None):
signal(SIGTERM, _prevterm)
raise Terminate
_prevterm = signal(SIGTERM, terminate)My favorite signal surprise was running nginx and/or httpd in the foreground and wondering why on earth it quit whenver i resized the window. Turns out, they use SIGWINCH (which is sent on WINdow CHange) for graceful shutdown. It's a silly, silly problem.