在WIN32下，在一个进程里我们可以使用CreateProcess()创建一个进程，然后通过调用WaitForSingleObect(), WaitForMultipleObject()等待进程退出。那么在linux下该如何实现呢?

          以下的代码实现了一个daemon程序, daemon程序负责系统启动其它所有App，当其它应用出现异常退出的时候，daemon程序会重新启动它们。

/******************************************************************** filename:   daemon.ccreated:    2013-07-17author:     firehood purpose:    daemon implement*********************************************************************/ #include 
    
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              typedef enum APP_ID_{ APP_ID_MIN, APP_ID_RTMP = APP_ID_MIN, APP_ID_VIDTRANSFILT, APP_ID_SOS, // APP_ID_MAX,}APP_ID;typedef struct APP_INFO_{ APP_ID id; // app id const char* app_path; // app file path const char* cmdline; // app cmdline int start_interval; // waitting time before starting the app. (unit:ms)}APP_INFO;static APP_INFO APP_INFO_Array[] = { {APP_ID_RTMP, "/opt/exe/crtmpserver/sbin/crtmpserver", "/opt/exe/crtmpserver/etc/crtmpserver.lua" ,0}, {APP_ID_VIDTRANSFILT, "./VidTransFilt", NULL, 2000}, {APP_ID_SOS, "/opt/exe/sos", NULL, 5000},};pid_t APP_pid[APP_ID_MAX];int ExecuteApp(const char *app_path,const char *argv[]);int GetAppIdByPid(pid_t pid);int main(void){ /* Our process ID and Session ID */ pid_t pid, sid; /* Fork off the parent process */ pid = fork(); if (pid < 0) { exit(EXIT_FAILURE); } /* If we got a good PID, then we can exit the parent process. */ if (pid > 0) { exit(EXIT_SUCCESS); }#if 0 /* Change the file mode mask */ umask(0); /* Open any logs here */ /* Create a new SID for the child process */ sid = setsid(); if (sid < 0) { /* Log the failure */ exit(EXIT_FAILURE); } /* Change the current working directory */ if ((chdir("/")) < 0) { /* Log the failure */ exit(EXIT_FAILURE); } /* Close out the standard file descriptors */ close(STDIN_FILENO); close(STDOUT_FILENO); close(STDERR_FILENO);#endif /* Daemon-specific initialization goes here */ printf("Daemon is running..\n"); int nAppCount = sizeof(APP_INFO_Array)/sizeof(APP_INFO); printf("Daemon: AppCount is [%d]\n",nAppCount); int i = 0; for(i =0; i
              
               =0 && app_id!=APP_ID_RTMP) { // restart the app APP_pid[app_id] = ExecuteApp(APP_INFO_Array[app_id].app_path,APP_INFO_Array[app_id].cmdline); } } exit(EXIT_SUCCESS);}int GetAppIdByPid(pid_t pid){ int i = 0; for(i = 0; i