多进程中fork

linux下多进程 （fork）

这里只是简单实用fork， 大家想了解具体 欢迎到我的gitee
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#include<stdio.h>
#include<unistd.h>
#include<stdlib.h>
int main() {
    int pid;
    printf("before fork()...");
    fflush(stdout);
    if((pid = fork()) < 0) { // fork对输出缓冲区进行复制
        perror("fork");
    }
    if(pid == 0) {
        printf("In Child\n");
    } else {
        sleep(1);
        printf("In father\n");
    }
    printf("END FORK!\n");
    return 0;
}

#include<stdio.h>
#include<unistd.h>
#include<stdlib.h>

int main() {
    int pid, x = 0;
    for(int i = 1; i <= 3; i++) {
        if((pid = fork()) < 0) {
            perror("fork()");
            continue;
        }
        if(pid == 0) {
            x = i;
        }
    }
    printf("I/m %dth child.\n", x);
    sleep(60);
   // printf("father%d\n", x);
    return 0;
}

exec

#include<stdio.h>
#include<unistd.h>
#include<stdlib.h>
#include<string.h>
#include<sys/wait.h>
int main(int argc, char **argv) {
    pid_t pid;
    char filename[512] = {0};
    char o_name[512] = {0};
    char f_type[256] = {0};
    char cmd[512] = {0};
    if(argc < 2) {
        fprintf(stderr, "Usage: %s filename arg...\n", argv[0]);
        return 1;
    }

    strcpy(filename, argv[1]);
    //a.c b.cpp
    char *sub;

    sub = strrchr(filename, '.');
    strncpy(o_name, filename, sub - filename);
    strcpy(f_type, sub);

    if(!strcmp(f_type, ".c")) {
        strcpy(cmd, "gcc");
    } else if(!strcmp(f_type, ".cpp")) {
        strcpy(cmd, "g++");
    } else {
        fprintf(stderr, "Not support File Type\n");
        return 2;
    }

    if((pid = fork()) < 0) {
        perror("fork");
        return 3;
    } 
    if(pid == 0) {
        execlp("vim", "vim", filename, NULL);
    }
    wait(NULL);
    if((pid = fork()) < 0) {
        perror("fork");
        return 3;
    }
    if(pid == 0) {
        execlp(cmd, cmd, filename, "-o", o_name, NULL);
    }
    int status; //子进程状态
    wait(&status);
    if(status == 0) {
        printf("OK\n");
        char name[25] = "./";
        strcat(name, o_name);
        execlp(name,name,NULL, NULL);
    } 
    return 0;
}