Is there an attention-free way to reboot from MacOS into Bootcamp/Windows? The standard way to reboot from MacOS into a Bootcamp Windows partition is to restart, hold Option, then manually select the Windows partition. Is there a single Terminal command or menubar application that can do this as well? I'm looking for some kind of single action I can fire off to handle the entire booting-into-Windows scheme.
With System Integrity Protection enabled, this is difficult to accomplish. However, this is not impossible. For example, you can install a third party Boot Manager such as rEFInd. You can then install scripts which can configure rEFInd to instruct the firmware to boot Windows after restarting the Mac. 


  Note: I do not know how the new T2 Security Chip will restrict the capabilities of rEFInd.


The idea is simple. The process takes place in the following steps.


rEFInd is installed on the Mac in either an EFI, FAT32 or ExFAT partition.
The rEFInd is set to be the default for the firmware to boot.
The rEFInd plain text configuration files are setup to instruct the firmware to boot macOS.
The BASH script command or AppleScript application is installed in macOS.
When this script or application executes, the rEFInd configuration files are modified so Windows will be booted instead of macOS.
You can either restart the Mac or have the script or application do so.