#include <head.h>
int main(int argc,const char * argv[])
{
    for(int i=0;i<2;i++){
        fork();
        printf("-");
    }
    return 0;
}

#include <head.h>
int main(int argc,const char * argv[])
{
    pid_t pid;
    pid = fork();
    if(pid == -1){
        PRINT_ERR("fork error");
    }else if(pid == 0){
        //子進(jìn)程
        printf("這個(gè)就是子進(jìn)程\n");
    }else{
        //父進(jìn)程
        printf("這個(gè)就是父進(jìn)程\n");
    }
    return 0;
}

#include <head.h>
int main(int argc, const char* argv[])
{
    pid_t pid;
    pid = fork();
    if (pid == -1) {
        PRINT_ERR("fork error");
    } else if (pid == 0) {
        //子進(jìn)程
        while (1) {
            sleep(1);
            printf("這個(gè)就是子進(jìn)程\n");
        }
    } else {
        //父進(jìn)程
        while (1) {
            sleep(1);
            printf("這個(gè)就是父進(jìn)程\n");
        }
    }
    return 0;
}

#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>
#include <stdlib.h>
int main(int argc, char const *argv[])
{
    pid_t pid;
    if((pid = fork()) ==-1){
        printf("創(chuàng)建進(jìn)程失敗\n");
        exit(-1);
    }else if(pid == 0){
        pid_t tid;
        if((tid = fork())==-1){
            printf("%d,%d\n",getpid(),getppid());
        }else if(pid == 0){
            printf("%d,%d\n",getpid(),getppid());
        }else{
            printf("%d\n",getpid());
        }
    }
    while(1);
    return 0;
}

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <unistd.h>
#include <sys/stat.h>
#include <fcntl.h>
char destfile[32]={0};
int get_length(char const *arcfile)
{
    int fd,cd,length;
    if((fd=open(arcfile,O_RDONLY))==-1){
        printf("open file error");
        exit(-1);
    }
    snprintf(destfile,sizeof(destfile),"new_%s",arcfile);
    if((cd==open(destfile,O_WRONLY|O_TRUNC|O_CREAT,0666)==-1)){
    }
    length = lseek(fd,0,SEEK_END);
    return length;
}
int copy_file(const char* srcfile,const char* destfile,int start,int length)
{
    int sfd,dfd,ret,count = 0;
    char buff[128] = {0};
    int counts=0;
    if((sfd=open(srcfile,O_RDONLY))==-1){
        printf("open error");
    }
    if((dfd=open(destfile,O_WRONLY))==-1){
        printf("open file error");
    }
    lseek(sfd,start,SEEK_SET);
    lseek(dfd,start,SEEK_SET);
    while (1){
       ret = read(sfd,buff,sizeof(buff));
       if(ret == 0){
            break;
       } 
        count+=ret;
       if(count >= length){
            write(dfd,buff,length-(count-ret));
            break;
       }
       write(dfd,buff,ret);
    }
    return 0;
}
int main(int argc, char const *argv[])
{
    pid_t pid;
    if(argc!=2){
        printf("輸入格式錯(cuò)誤，請(qǐng)重新輸入\n");
        exit(-1);        
    }
    int length = get_length(argv[1]);
    if(length < 0){
        printf("srcfile error\n");
        return -1;
    }
    if((pid=fork())==-1){
        printf("fork error");
        exit(-1);
    }else if(pid == 0){
        copy_file(argv[1],destfile,length/2,length-length/2);
    }else{
        copy_file(argv[1],destfile,0,length/2);
    }
    return 0;
}

#include <head.h>
int main(int argc, const char* argv[])
{
    pid_t pid;
    pid = fork();
    if (pid == -1) {
        PRINT_ERR("fork error");
    } else if (pid == 0) {
        //子進(jìn)程
    } else {
        //父進(jìn)程
        while(1);
    }
    return 0;
}

#include <head.h>
int main(int argc, const char* argv[])
{
    pid_t pid;
    pid = fork();
    if (pid == -1) {
        PRINT_ERR("fork error");
    } else if (pid == 0) {
        //子進(jìn)程
        printf("pid = %d\n",getpid());
        while (1);
    } else {
        //父進(jìn)程
    }
    return 0;
}

#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdlib.h>
#define ERROR(msg) do{\
    printf("%s %s %d\n",__FILE__,__func__,__LINE__);\
    printf(msg);\
    exit(-1); \
}while(0)
int main(int argc, char const *argv[])
{
    pid_t pid;
    if ((pid == fork()) == -1){
        ERROR("fork error");
    }else if(pid == 0){
        int fd;
        setsid();
        chdir("/");
        umask(0);
        for(int i = 3; i < getdtablesize(); i++){
            close(i);
        }
        if((fd = open("my.log", O_RDWR, O_APPEND, O_CREAT, 0666)) == -1){
            ERROR("open error");
        }
        dup2(fd, 0);
        dup2(fd, 1);
        dup2(fd, 2);
        while(1){
            sleep(1);
            printf("我是子進(jìn)程\n");
            fflush(stdout);
        }
    }else{
        printf("父親進(jìn)程已經(jīng)結(jié)束....\n");
        exit(-1);
    }
    return 0;
}