Cheat Sheet: Ubiquiti EdgeRouter Lite Firmware Upgrade via CLI

    N.B.:

	Assumes a modicum of knowledge.  It's a cheat sheet, not a tutorial
	for n00bs

	New, out-of-the-box ERLite.  Network server with FTP service at
	192.168.1.9

	All done with CLI from a Linux box

	Accessing the console (serial) port using "screen"

	    $ screen /dev/ttyS5 115200,cs8,-parenb,-cstopb,-hupcl

	One could use "ssh ubnt@192.168.1.1" as well, but it's good to
	know you can use the serial console.  (In case prayer doesn't work.)

	Official Ubiquiti KnowledgeBase article on firmware upgrades:

	    https://help.ubnt.com/hc/en-us/articles/205146110-EdgeRouter-Upgrading-EdgeOS-Firmware


    Download the new install file

	$ wget https://dl.ubnt.com/firmwares/edgemax/v1.10.x/ER-e100.v1.10.7.5127970.tar

    Create an sha256sum check file and check the download

	$ sha256sum -c ER-e100.v1.9.7.5001798.sha256sum

    Copy the update to the ERLite

	$ scp ER-e100.v1.10.7.5127970.tar ubnt@192.168.1.1:~/tmp/

	    N.B.: I'd logged into the ERLite, beforehand, and created the
		  "tmp" directory in "ubnt"s home.  You don't need to use
		  it.  It's just habit for me.

    Log in to the ERLite

    Save config

	$ configure
	$ save ftp://someuser:somepass@192.168.1.9/config.boot-20181127-01
	$ exit

    Optional: Make room, if needed

	$ delete system image

	    This will delete only the older, unused image

    Do the upgrade

	$ add system image tmp/ER-e100.v1.10.7.5127970.tar

    Verify the new image is the default boot

	$ show system image

	N.B.: If for some reason you want to swap default images

	    $ set system image default-boot .

    Reboot

	$ reboot now

    Log back in

    Optional: Upgrade boot loader

	WARNING: This is the step most likely to brick the EdgeRouter!

	$ show system boot-image
	$ add system boot-image
	
	$ reboot now

	(Pray)

    Log back in (if the prayers worked)

    Restore config

	$ configure
	$ load ftp://someuser:somepass@192.168.1.9/config.boot-20181127-01
	$ compare

	If necessary:

	    $ commit
	    $ save

	Or, if not:

	    $ discard

	$ exit


    Created: 2018-11-28		Updated: 2018-11-30