Hi! I am trying to test for signal handling race conditions (specifically, I suspect the kernel side of connect() does interesting things if the server response arrives while the program executes a signal handler) and want to flood a program with lots of signals. So I have run this: --- #!/bin/bash while [ 1 -eq 1 ]; do killall -s SIGURG wget 2> /dev/null done --- ...and then then executed: strace wget -O - "http://kernel.org" ... connect(3, {sa_family=AF_INET, sin_port=htons(80), sin_addr=inet_addr("198.145.20.140")}, 16) = ? ERESTARTSYS (To be restarted) --- SIGURG (Urgent I/O condition) @ 0 (0) --- connect(3, {sa_family=AF_INET, sin_port=htons(80), sin_addr=inet_addr("198.145.20.140")}, 16) = ? ERESTARTSYS (To be restarted) --- SIGURG (Urgent I/O condition) @ 0 (0) --- connect(3, {sa_family=AF_INET, sin_port=htons(80), sin_addr=inet_addr("198.145.20.140")}, 16) = 0 ... It shows that signals arrive, but no interesting behaviour yet. I suspect this is because the rate signals are sent is too low. So I come up with this: --- #include <sys/types.h> #include <signal.h> #include <stdio.h> int main(int argc, char **argv) { int pid; int rc = 0; if (argc < 2) return 1; pid = atoi(argv[1]); if (pid <= 1 || pid >= 65536) return 1; printf("kill %d %d\n", pid, SIGURG); while (kill(pid, SIGURG) == 0) { printf("signal sent\n"); /* probably slow, remove later */ } perror("killloop end"); return 0; } --- #!/bin/bash while [ 1 -eq 1 ]; do ./a.out `ps a|grep wget|grep -v grep|sed "s/^[^0-9]*\([0-9]*\).*$/\1/"` done --- The output looks like this: kill 15574 23 signal sent signal sent signal sent ... signal sent signal sent signal sent killloop end: No such process However, no signal arrives. But if I change SIGURG to SIGTERM, they arrive! Why does SIGURG arrive when sent with "killall -s SIGURG wget", but not when sent with my test prog? -Michi -- programing a layer 3+4 network protocol for mesh networks see http://michaelblizek.twilightparadox.com