If you already opened KOReader, the filemanager lets you open a file in a "GUI" text editor, as rtiangha was referring to above, for a more intuitive experience than Vi! Edit:On reading properly this time, OP said "macros" and "emacs", so that was a whoosh on my part.Vi it is!
And I just tried the vlasovsoft editor, from the home page, as Alastair_S suggested above, and it also worked on my Clara HD. A shame that the Konsole terminal didn't work - I just got an empty screen.
And some people have got the USB host mode working with Clara HD, with powered microUSB connector since the Clara does not itself power the hub, but getting a USB keyboard up and running is a work in progress. UPDATE : now working great on my Clara HD but requiring setup of Xorg chroot, as mentioned in following link.
https://www.mobileread.com/forums/sh...d.php?t=340418
*Using the USB keyboard on the Clara HD required setup using linux command line, buying a special micro-usb adapter that you would have to attach to a USB power source, and switching to a special container app which may have ghosting and refresh issues, and is not as finely optimized in user experience as say KOReader, Plato, etc, plus you have to power off to leave.
So unless that sounds like part of the fun to you, I would follow Quoth advice and choose my ereader accordingly!
*** USB KEYBOARD NOW USABLE IN KOREADER AS OF OCP-KOReader-v2023.06 ! ***
https://www.mobileread.com/forums/sh...&postcount=941
You can also mirror your phone keyboard
using the Linux script utility inside a chroot, and
using Fbpad framebuffer terminal otherwise.