signals

I have a parent process that spawns ten child processes and uses a SIGCHILD handler to notify when a child process has died. The child processes will notify when they have started and will then exit immediately. I use the SA_NODEFER flag to prevent SIGCHLD signals to get discarded when too many are coming in. The children are all being correctly terminated and reaped, but in this script and also when terminating two at the same time via the console signals send at the same time always appear as one. #define _POSIX_C_SOURCE 200809L #include <stdio.h> #include <sys/types.h> #include <sys/wait.h>

I am experiencing a strange problem with the the popen and fgets library functions on a Linux system. A short program demonstrating the problem is below that: Installs a signal handler for SIGUSR1 . Creates a secondary thread to repeatedly send SIGUSR1 to the main thread. In the main thread, repeatedly executes a very simple shell command via popen() , gets the output via fgets() , and checks to see if the output is of the expected length. The output is unexpectedly truncated intermittently. Why? Command-line invocation example: $ gcc -Wall test.c -lpthread && ./a.out iteration 0 iteration 1

Okay so I am trying to teach myself on how to do signalling, and I came across a hiccup and I can't figure out what I'm doing wrong. What is going on right now is: it is executing the parent then goes to child and then back to parent.. It's not doing what I want it to do which is execute the parent (which the user defines the amount of time it runs) then kills it then go to child and run itself at the same amount of time. #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <signal.h> #include <sys/types.h> // for wait #include <sys/wait.h> // for wait void action(int); void

As I understand, the best way to achieve terminating a child process when its parent dies is via prctl(PR_SET_PDEATHSIG) (at least on Linux): How to make child process die after parent exits? There is one caveat to this mentioned in man prctl : This value is cleared for the child of a fork(2) and (since Linux 2.4.36 / 2.6.23) when executing a set-user-ID or set-group-ID binary, or a binary that has associated capabilities (see capabilities(7)). This value is preserved across execve(2). So, the following code has a race condition: parent.c: #include <unistd.h> int main(int argc, char **argv) {

Python provides a signals module and os.kill ; does it have a facility for sigqueue() (real-time signals with attached data)? What are the alternatives? You could do it with ctypes >>> from ctypes import * >>> c = cdll.LoadLibrary("libc.so.6") >>> c.sigqueue <_FuncPtr object at 0xb7dbd77c> >>> c.sigqueue(100, 10, 0) -1 >>> You'll have to look up how to make a union in ctypes which I've never done before but I think is possible. One alternative, if no one has done it yet, would be to wrap the C library yourself - should be pretty quick and painless. Look here for more details. 来源： https:/

QNetworkConfigurationManager::configurationChanged() signal is not getting called by the system when I am inserting a LAN cable with a valid IP(Ethernet interface). It is getting called for WLAN and USB interface but not for ETHERNET config changes Hope to get some pointers on this. 来源： https://stackoverflow.com/questions/14359657/qnetworkconfigurationmanagerconfigurationchanged-signal-not-getting-called-for