fork

问题 I am working on Bryant and O'Hallaron's Computer Systems, A Programmer's Perspective . Exercise 8.16 asks for the output of a program like (I changed it because they use a header file you can download on their website): #include <stdio.h> #include <stdlib.h> #include <sys/types.h> #include <sys/wait.h> #include <errno.h> #include <unistd.h> #include <string.h> int counter = 1; int main() { if (fork() == 0){ counter--; exit(0); } else{ Wait(NULL); printf("counter = %d\n", ++counter); } exit(0)

问题 I have a code in C that forks itself sometimes, each fork does something then returns an error code. Currently, each child process returns its ID (0..n). void other(int numero){ ... exit(numero); } int main(...){ for(int i = 0; i < 6; i++){ if(fork() == 0){ other(i); } } int order[6]; for(int i = 0; i < 6; i++){ int code; waitpid(0, &code, 0); order[i] = code; // <-- HERE } } Weirdly, this returns a multiple of the real value. By replacing the line I marked with : order[i] = code >> 8; I

问题 If I do this below: for i in range(10000): os.fork() What's going on? don't consider reaping.. I just wanna know about os.fork() can make how much processes in linux, if it 's just like windows, only can make about 2000 processes, how the next 8000 processes will do? Thanks. 回答1: os.fork() spawns a new OS-level process. Any limits on the number of those aren't dependent on Python, but on the operating system. According to this previous question, on Linux you can find out about any software

问题 I need to catch the returned value of a child process.. The problem is: with using the waitpid() function I can catch only 8 bits of the returned value WEXITSTATUS(wstatus) returns the exit status of the child. This consists of the least significant 8 bits of the status argument that the child specified in a call to exit(3) or _exit(2) or as the argument for a return statement in main(). This macro should be employed only if WIFEXITED returned true. How can I catch the full int value that is

问题 I need to catch the returned value of a child process.. The problem is: with using the waitpid() function I can catch only 8 bits of the returned value WEXITSTATUS(wstatus) returns the exit status of the child. This consists of the least significant 8 bits of the status argument that the child specified in a call to exit(3) or _exit(2) or as the argument for a return statement in main(). This macro should be employed only if WIFEXITED returned true. How can I catch the full int value that is

问题 I need to catch the returned value of a child process.. The problem is: with using the waitpid() function I can catch only 8 bits of the returned value WEXITSTATUS(wstatus) returns the exit status of the child. This consists of the least significant 8 bits of the status argument that the child specified in a call to exit(3) or _exit(2) or as the argument for a return statement in main(). This macro should be employed only if WIFEXITED returned true. How can I catch the full int value that is

问题 In c++ create chain of n processes with n as input and the output of processes should be as parent1->child1(parent2)-->child2(parent3),by using recursive function im able to generate the output but unable to exit the loop i also need help in sending an input of n for which the loop should break. below is my code: #include <sys/types.h> #include <unistd.h> #include <stdio.h> #include <stdlib.h> #include <sys/wait.h> int foo(const char *whoami) { printf("I am a %s. My pid is:%d my ppid is %d\n"

问题 In c++ create chain of n processes with n as input and the output of processes should be as parent1->child1(parent2)-->child2(parent3),by using recursive function im able to generate the output but unable to exit the loop i also need help in sending an input of n for which the loop should break. below is my code: #include <sys/types.h> #include <unistd.h> #include <stdio.h> #include <stdlib.h> #include <sys/wait.h> int foo(const char *whoami) { printf("I am a %s. My pid is:%d my ppid is %d\n"

问题 Child and parent process execution is parallel and which starts first depends on OS scheduling. But what can be done to start child always before the parent? This is the pseudo code for my problem, int start_test() { pid_t pid; pid = fork(); if(pid == 0) { execv("XXX", XXX); } else if(pid > 0) { pid = fork(); if(pid == 0) { execv("XXX", XXX); } else { // Do something } } return 0; } int main() { start_test(); return 0; } I wants to make first execv execute first than parent creates new

问题 Child and parent process execution is parallel and which starts first depends on OS scheduling. But what can be done to start child always before the parent? This is the pseudo code for my problem, int start_test() { pid_t pid; pid = fork(); if(pid == 0) { execv("XXX", XXX); } else if(pid > 0) { pid = fork(); if(pid == 0) { execv("XXX", XXX); } else { // Do something } } return 0; } int main() { start_test(); return 0; } I wants to make first execv execute first than parent creates new