2014/3/4实验代码

//daemon_init.c
 //创建一个守护进程

#include<stdlib.h>

#include<unistd.h>

#include<signal.h>

#include<sys/param.h>

#include<sys/types.h>

#include<sys/stat.h>

void init_daemon(void) //initialize daemon

{

 int pid;

 int i;

 if(pid=fork()) //end parent process

   exit(0); 

 else if(pid<0) //quit if fail to create

   exit(1);

 setsid(); //create new dialogue

 if(pid=fork())

   exit(0); //quit if it's the first child process

 else if(pid<0)

   exit(1); //quit if fail to create

 for(i=0;i<NOFILE;i++) //close opened file description

    close(i);

 chdir("/tmp"); //change directory to /tmp

 umask(0); //reset file create mask code

 return;

}

/***********************************************************************************************************************************************************************/

//daemon_test.c
//创建一个守护进程，每隔60秒把当前系统时间存入/tmp/test.log文件中

#include<stdio.h>

#include<time.h>

void init_daemon(void);

int main(int argc,char* argv[])

{

 FILE* fp;

 time_t t;

 init_daemon(); //initialize a daemon

 while(1)

{

 sleep(60);

 if((fp=fopen("test.log","a"))>=0) //open file "test.log"

{

 t=time(0);

 fprintf(fp,"I'm here at %s\n",asctime(localtime(&t))); //print local time

 fclose(fp);

}

}

return 0;

}

/***********************************************************************************************************************************************************************/

//测试main函数的参数含义

#include<stdio.h>

int main(int argc,char* argv[])

{

 printf("%d\n",argc);

 printf("%s\n",argv[0]);

 printf("%s\n",argv[1]);

 printf("%s\n",argv[2]);

 printf("%c\n",argv[1][0]);

}

//执行./main_argument_test shadow walker的结果：

3

./main_argument_test

shadow 

walker

s

 
/***********************************************************************************************************************************************************************/

 //主进程等待子进程结束

#include<stdlib.h>

#include<stdio.h>

#include<sys/types.h>

#include<sys/wait.h>

#include<unistd.h>

int main(int argc,char* argv[])

{

 pid_t pid;

 char* msg;

 int k;

 int exit_code;

 pid=fork();

 switch(pid)

 {

  case 0: printf("Child process creation succeed.\n");

  msg="Child process is running";

  k=5; 

  exit_code=37;

  break;

  case -1: printf("Process creation failed.\n");

  exit(1);

  default:exit_code=0;

  break;

 }

 if(pid!=0)

 {

  int stat_val;

  pid_t child_pid;

  child_pid=wait(&stat_val);

  printf("Child process has exited, pid=%d\n",child_pid);

  if(WIFEXITED(stat_val))

 {

  printf("Child exited with code %d\n",WEXITSTATUS(stat_val));

 }

  else

 {

  printf("Child exited abnormally\n");

 }

 }

 else

 {

  while(k>0)

 {

  puts(msg);

  sleep(1);

  k--;

 }

 }

}