c - 我的守护程序代码在终端中完美执行，但未创建日志文件

Question

进程的 pid 正在终端中显示，但日志文件未在根目录中创建。请仔细检查这段代码并告诉我缺少什么。

终端输出:

process_id of child process 5611 

来源如下。

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <string.h>
#include <sys/inotify.h>
int main(int argc, char* argv[])
{
    FILE *fp= NULL;
    pid_t process_id = 0;
    pid_t sid = 0;
    int fd,wd,i=0,len=0;
    char pathname[100],buf[1024];
    process_id = fork();
    if (process_id < 0)
    {
        printf("fork failed!\n");
        exit(1);
    }
    if (process_id > 0)
    {
        printf("process_id of child process %d \n", process_id);
        // return success in exit status
        exit(0);
    }
    umask(0);
    sid = setsid();
    if(sid < 0)
    {
        exit(0);
    }
    chdir("/");
    close(STDIN_FILENO);
    close(STDOUT_FILENO);
    close(STDERR_FILENO);
    fp = fopen ("log.txt", "w+");
    fprintf(fp, "Logging info...\n");
    fflush(fp);
    fclose(fp);
    sleep(1);
    struct inotify_event *event;

    fd=inotify_init();
    wd=inotify_add_watch(fd,"/osa",IN_ALL_EVENTS);
    while(1)
    {
        i=0;
        len=read(fd,buf,1024);
        fp = fopen ("log.txt", "w+");
        fflush(fp);
        while(i<len)
        {
            event=(struct inotify_event *) & buf[i];
            if(event->mask & IN_OPEN)
            {
                fprintf(fp,"%s:was opened\n",event->name);
            }

            if(event->mask & IN_MODIFY)
            {
                fprintf(fp,"%s:file is modified",event->name);

            }
            if(event->mask & IN_DELETE)
            {
                fprintf(fp,"%s:was deleted\n",event->name);
            }
            i+=sizeof(struct inotify_event)+event->len;
        }
        fclose(fp);
    }
    return (0);
}

Answer 1

正在创建日志文件。您需要以 root 身份运行代码，因为日志文件在“/”目录中打开，通常只有 root 可以访问。