/bin/sh doesn’t have a -n option for echo. And if you symlink /bin/sh to bash and/or you invoke bash as /bin/sh (by, for example, prefacing your script with #!/bin/sh) it will behave like /bin/sh

A workaround would be to just use /bin/echo instead of the built-in command.

It looks like there’s no consensus on whether Bourne shell (not bash) has echo -n, but I notice that it says the POSIX echo doesn’t.

I thought it might be something like this at first, but the odd behavior in iTerm was a red herring. I’m reinstating the original /bin/bash and /bin/sh, and calling it a bug in abcde.