只有字符特殊文件和块特殊文件有一个st_rdev值。

Only character special files and block special files have an st_rdev value.

youdao

实际上，如果您想访问一个特定的块设备(如磁盘、分区、光盘驱动器等等)，事实上有几个不同的特殊文件可以引用。

In fact, when you want to access a particular block device (such as a disks, partition, CD-ROM drive, etc) you'll actually have several different special files to which you can refer.

youdao