The default action for things like SIGSEGV is to terminate your process but as you’ve installed a handler for it, it’ll call your handler overriding the default behavior. But the problem is segfaulting instruction may be retried after your handler finishes and if you haven’t taken measures to fix the first seg fault, the retried … Read more
What’s the best way to control which thread a signal is delivered to? As @zoli2k indicated, explicitly nominating a single thread to handle all signals you want handled (or a set of threads each with specific signal responsibilities), is a good technique. What is the best way to tell another thread (that might actually be … Read more
This is very much by design. There’s no reasonable way a user can select text when your program keeps scrolling the content of the console window. So the console host program simply stops reading your stdout/stderr output and your program hangs until the user completes the operation. This can be changed, you’ll have to call … Read more
If you do not lock the mutex in the codepath that changes the condition and signals, you can lose wakeups. Consider this pair of processes: Process A: pthread_mutex_lock(&mutex); while (condition == FALSE) pthread_cond_wait(&cond, &mutex); pthread_mutex_unlock(&mutex); Process B (incorrect): condition = TRUE; pthread_cond_signal(&cond); Then consider this possible interleaving of instructions, where condition starts out as FALSE: … Read more
As others have already said, to handle Control+D, handle “end of file”s. Control+D is a piece of communication between the user and the pseudo-file that you see as stdin. It does not mean specifically “end of file”, but more generally “flush the input I typed so far”. Flushing means that any read() call on stdin … Read more
With a signal handler. Here is a simple example flipping a bool used in main(): #include <signal.h> static volatile int keepRunning = 1; void intHandler(int dummy) { keepRunning = 0; } // … int main(void) { signal(SIGINT, intHandler); while (keepRunning) { // … Edit in June 2017: To whom it may concern, particularly those with … Read more
I have done some research around this topic, which turned out to be more popular than I anticipated. KindDragon’s reply was one of the pivotal points. I wrote a longer blog post on the topic and created a working demo program, which demonstrates using this type of system to close a command line application in … Read more
If the user or sysadmin did not kill the program the kernel may have. The kernel would only kill a process under exceptional circumstances such as extreme resource starvation (think mem+swap exhaustion).
You generally want to ignore the SIGPIPE and handle the error directly in your code. This is because signal handlers in C have many restrictions on what they can do. The most portable way to do this is to set the SIGPIPE handler to SIG_IGN. This will prevent any socket or pipe write from causing … Read more
You don’t say if the tree you want to kill is a single process group. (This is often the case if the tree is the result of forking from a server start or a shell command line.) You can discover process groups using GNU ps as follows: ps x -o “%p %r %y %x %c … Read more