Nautilus and other file managers that mount drives (i.e., the GUI) use the udisks command.

This provides a dynamic mount, where the mount point is created for the drive on-the-fly, and when the drive is unmounted, the mount point goes away.

See man 1 udisks for details on how to use this command (either manually, or called from a script/application). To learn more about how udisks works, see man 7 udisks.

To mount a device with udisks, you must specify a valid device name for the device. Specifying the device's volume name will not work. So, you can use udisks like this:

udisks --mount /dev/sdb1

When manually using udisks from the command-line, you might be best off to simply plug in a device, then run dmesg | tail shortly thereafter (see man dmesg and man tail) to discover the device name of the newly attached device.

This may not be the best way to write a script that mounts devices with udisks, however. I don't know exactly how you should do it, and it would be difficult to know since you haven't told us precisely what you want this script to do and when you want it to mount devices.