电脑技术学习

在Linux下防止某个程序被运行两次的方法

dn001
; 通过文件锁来实现,在程序运行的一开始,检查某文件是否存在,如果存在则说明改程序已经在运行了,如果不存在则利用open语句创建该文件,程序退出时关闭并删除此文件。
static char file_lock[sizeof(ctl_addr.sun_path)] = /var/run/file.pid;
  static bool file_lock_created = FALSE;
  
  static int
  create_lock(void)
  {
   int fd = open(file_lock, O_WRONLY | O_CREAT | O_EXCL | O_TRUNC,
   S_IRUSR | S_IRGRP | S_IROTH);
  
   if (fd < 0)
   {
   if (errno == EEXIST)
   {
   fprintf(stderr, "file: lock file "%s" already existsn", file_lock);
   exit_file(10);
   }
   else
   {
   fprintf(stderr, "file: unable to create lock file "%s" (%d %s)n"
   , file_lock, errno, strerror(errno));
   exit_file(1);
   }
   }
   file_lock_created = TRUE;
   return fd;
  }
  
  static bool
  fill_lock(int lockfd)
  {
   char buf[30]; /* holds "n" */
   pid_t pid;
   int len;
  
   pid = getpid();
   len = snprintf(buf, sizeof(buf), "%un", (unsigned int) pid);
   bool ok = len > 0 && write(lockfd, buf, len) == len;
  
   close(lockfd);
   return ok;
  }
  
  static void
  delete_lock(void)
  {
   if (file_lock_created)
   {
   //delete_ctl_socket();
   unlink(file_lock); /* is noting failure useful? */
   }
  }

标签: linux