Whow, a book to learn ed... just take a look to the man page. If you are a vi user you should need only 5 minutes to see what subset of ex commands its grandpa supports.
Lets change the home partition to another disk, so people reading this nonsense don't get scared... $ ed /etc/fstab 518 # print with line numbers all the file %n 1 e32af7a7d8628e71.b none swap sw 2 e32af7a7d8628e71.a / ffs rw 1 1 3 e32af7a7d8628e71.l /home ffs rw,nodev,nosuid,noatime 1 2 4 e32af7a7d8628e71.d /tmp ffs rw,nodev,nosuid 1 2 5 e32af7a7d8628e71.f /usr ffs rw,nodev 1 2 6 e32af7a7d8628e71.g /usr/X11R6 ffs rw,nodev 1 2 7 e32af7a7d8628e71.h /usr/local ffs rw,wxallowed,nodev 1 2 8 e32af7a7d8628e71.k /usr/obj ffs rw,wxallowed,nodev,nosuid 1 2 9 e32af7a7d8628e71.j /usr/src ffs rw,nodev,nosuid 1 2 10 e32af7a7d8628e71.e /var ffs rw,nodev,nosuid 1 2 11 swap /mfs mfs rw,nodev,nosuid,-s=500M 0 0 # ok, we are going to change the 3rd line, lets see our disk's ids. ! sysctl hw.disknames hw.disknames=sd0:e32af7a7d8628e71,sd1:4b96767efbfab476 # we need to change just the first word, so best use regexp 3s/[^.]*/4b96767efbfab476/ # be sure! 3p 4b96767efbfab476.l /home ffs rw,nodev,nosuid,noatime 1 2 # ok, that's all folks wq 518
Fiddling around with configuration files with ed is like being tied up with your hands and feet behind your back being told to eat a pizza from the floor! Typing everything out using echo is preferably to using ed
Give me a break...
Theo's answer: "For the same reasons it doesn't contain a web browser:Not required, \ and besides that far too large." That is ridicules! Out of room? What does that even mean? Are you still using floppy disks!? Oh, what a surprise: https://marc.info/?l=openbsd-misc&m=135794041929033&w=2 Double sigh!
What an attitude... I'm really surprise how nice this people have been to you. But hey, this is not my house so I'll keep walking...

