freeBSD mount CD-ROM

Mount the optical drive
mount -t cd9660 /dev/cd0 /cdrom Pay attention here. The CD-ROM setting file under /dev is not necessarily cd0 and may be other, depending on the specific situation, but also pay attention to one point, be sure to mount the CD-ROM to the /dev/cdrom file, otherwise it may appear questionable.
Unmount CD-ROM
umount -f /cdrom
mount USB
mount -t msdos /dev/da0s1 /mnt/usb
unmount USB
umount /dev/da0s1