[R] R console not echoing input

[Professor Bickis]

I have a weird problem running R.app 3.3.2 under Mac OS X 10.10.5.

I was trying to interrupt a command line using various Control codes until I discovered that “Esc” is the escape key.  (Makes sense!)
Now I find that while I can enter new commands to R, they no longer echo back, so I cannot see what I am typing.  On unix terminals CTL-Q will reset this, but it does not seem to work on the R console.
I tried
> system("stty echo")

but was told

stty: stdin isn’t a terminal

So I tried the following, but it did not give me any info I can use.

> isatty(stdin)
[1] FALSE
> stdin()
description     class           mode    text    opened          can read        can write
"stdin"         "terminal"      "r"     "text"  "opened"        "yes"           "no"
>       stdout()
description     class           mode    text    opened          can read        can write
"stdout"        "terminal"      "w"     "text"  "opened"        "no"            "yes"


What have I done, and how can I reset it?

I know I can quit the R session and start again, but if I have lots of graphics windows on the screen, I don’t want to lose them all and have to recreate them, not to mention having to play with the par parameters again.

Mik Bickis