在守护进程中登录到文件

如何解决在守护进程中登录到文件

我正在遵循一个快速指南，该指南是如何在C中创建守护进程的，该过程是对Stack Overflow questions之一的回答。

这是一个问题，为了使这段代码对我来说更容易，我创建了一个文件，其中记录了一些调试数据，但是当我创建第二个 fork（）时，我的新孩子似乎什么都不记录。我检查存在的进程列表。我不知道为什么它没有将任何内容打印到我的文件中。有任何想法吗？ 0.o

我调整后的代码：

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <syslog.h>

#define LOG_FILE "/local_pv/asiwek/daemon_test/daemon_log.log"

static void skeleton_daemon(FILE* file)
{
    pid_t pid;

    /* Fork off the parent process */
    pid = fork();

    /* An error occurred */
    if (pid < 0)
        exit(EXIT_FAILURE);

    /* Success: Let the parent terminate */
    if (pid > 0)
        exit(EXIT_SUCCESS);
    
    fprintf(file,"I'm a child! \n");
    /* On success: The child process becomes session leader */
    if (setsid() < 0)
    {
        fprintf(file,"ERROR: setsid()! \n");
        exit(EXIT_FAILURE);
    }

    /* Catch,ignore and handle signals */
    //TODO: Implement a working signal handler */
    signal(SIGCHLD,SIG_IGN);
    signal(SIGHUP,SIG_IGN);

    /* Fork off for the second time*/
    pid = fork();
    
    /* An error occurred */
    if (pid < 0)
    {   
        fprintf(file,"ERROR: fork()! \n");
        exit(EXIT_FAILURE);
    }
    /* Success: Let the parent terminate */
    if (pid > 0)
    {
        fprintf(file,"I'm a parent of the child! pid : %d",pid);
        exit(EXIT_SUCCESS);
    }
    
    fprintf(file,"New Child!! \n"); // here program stops logging
    
    /* Set new file permissions */
    umask(0);

    /* Change the working directory to the root directory */
    /* or another appropriated directory */
    chdir("/local_pv/asiwek/daemon_test/");
    fprintf(file,"chdir \n");

    /* Close all open file descriptors */
    int x;
    for (x = sysconf(_SC_OPEN_MAX); x>=0; x--)
    {
        close (x);
    }

    /* Open the log file */
    //openlog ("firstdaemon",LOG_PID,LOG_DAEMON);
    fprintf(file,"skeleton_daemon() end. \n");
}

int main()
{
    FILE* f = fopen(LOG_FILE,"w");
    skeleton_daemon(f);
    fprintf(f,"Oh boy I am a daemon!!! \n");

    while (1)
    {
        //TODO: Insert daemon code here.
      //  syslog (LOG_NOTICE,"First daemon started.");
        fprintf(f,"Some log.");
        sleep (200);
        break;
    }

    //syslog (LOG_NOTICE,"First daemon terminated.");
    //closelog();
    fclose(f);

    return EXIT_SUCCESS;
}