有两个 USB 盘，一个名为 USB-A，另一个名为 USB-B。插入usb-A时fdisk -l信息如下
Device Boot Start End Sectors Size Id Type
/dev/sda1 * 2048 195311615 195309568 93.1G 83 Linux
/dev/sda2 195311616 292968447 97656832 46.6G 83 Linux
/dev/sda3 292968448 390625279 97656832 46.6G b W95 FAT32
/dev/sda4 390627326 488396799 97769474 46.6G 5 Extended
/dev/sda5 390627328 468944895 78317568 37.4G b W95 FAT32
/dev/sda6 468946944 488396799 19449856 9.3G 82 Linux swap / Solaris
Disk /dev/sdb: 1015.5 MiB, 1064828928 bytes, 2079744 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x0d0c0b0a
Device Boot Start End Sectors Size Id Type
/dev/sdb1 * 63 2072384 2072322 1011.9M 6 FAT16
现在usb-A可以挂载为/media/debian8/CC1F-721E，usb-A上的文件可以读写。
插入usb-B时fdisk -l信息如下
Device Boot Start End Sectors Size Id Type
/dev/sda1 * 2048 195311615 195309568 93.1G 83 Linux
/dev/sda2 195311616 292968447 97656832 46.6G 83 Linux
/dev/sda3 292968448 390625279 97656832 46.6G b W95 FAT32
/dev/sda4 390627326 488396799 97769474 46.6G 5 Extended
/dev/sda5 390627328 468944895 78317568 37.4G b W95 FAT32
/dev/sda6 468946944 488396799 19449856 9.3G 82 Linux swap / Solaris
Disk /dev/sdb: 14.9 GiB, 16005464064 bytes, 31260672 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
为什么USB-B不能像USB-A一样自动挂载，USB-B上的文件不能读写？
如何让usb-B能像usb-A一样自动挂载？