简单的waitpid函数的使用。

来源：互联网发布：中国f1车队知乎编辑：程序博客网时间：2024/05/30 05:42
#include <stdio.h>#include <stdlib.h>#include <sys/types.h>#include <unistd.h>#include <sys/wait.h>void die(const char *msg){perror(msg);exit(1);}void child2_do(){printf("In child2: execute 'date'\n");sleep(5);    if (execlp("date", "date", NULL) < 0) {perror("child2 execlp");    }}void child1_do(pid_t child2, char *argv){pid_t pw;do{if (*argv == '1') {pw = waitpid(child2, NULL, 0);}        else {pw = waitpid(child2, NULL, WNOHANG);        }        if (pw == 0) {printf("In child1 process:\nThe child2 process has not exited!\n");            sleep(1);        }    }while (pw == 0);if (pw == child2) {printf("Get child2 %d.\n", pw);        sleep(5);if (execlp("pwd", "pwd", NULL) < 0) {perror("child1 execlp");        }    }    else {printf("error occured!\n");    }}void father_do(pid_t child1, char *argv){pid_t pw;do {if (*argv == '1') {pw = waitpid(child1, NULL, 0);        }        else {            pw = waitpid(child1, NULL, WNOHANG);        }if (pw == 0) {            printf("In father process:\nThe child1 process has not exited.\n");sleep(1);        }    }while (pw == 0);if (pw == child1) {printf("Get child1 %d.\n", pw);        if (execlp("ls", "ls", "-l", NULL) < 0) {perror("father execlp");        }    }    else {printf("error occured!\n");    }}int main(int argc, char *argv[]){pid_t child1, child2;if (argc < 3) {        printf("Usage: waitpid [0 1] [0 1]\n");        exit(1);    }    child1 = fork();    if (child1 < 0){         die("child1 fork");    }    else if (child1 == 0) {        child2 = fork();        if (child2 < 0) {            die("child2 fork");        }else if (child2 == 0) {child2_do();        }else {             child1_do(child2, argv[1]);}    }    else {father_do(child1, argv[2]);    }    return 0;}
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