How to type telnet escape character in OS X terminal
I enabled the Finnish and Swedish keyboard layouts and experimented with Terminal on OS X 10.8.5 a bit…


Control-å generated ^] (U+001D)
å (LATIN SMALL LETTER A WITH RING ABOVE) is an unmodified key in these layouts.
It is located where [ (LEFT SQUARE BRACKET) is with US layouts.
Control-ä generated ^[ (U+001B)
ä (LATIN SMALL LETTER A WITH DIAERESIS) is an unmodified key in these layouts.
It is located where ' (APOSTROPHE) is with US layouts.
Control-- generated ^_ (U+001F)
- (HYPEN-MINUS) is an unmodified key in these layouts.
It is located where / (SOLIDUS, a.k.a. “forward slash”) is with US layouts.


As normal, Control-Space generated ^@ (U+0000) and Delete generated ^? (U+007F).

I did not find any combination that generated ^\ (U+001C) or ^^ (U+001E) in Terminal though. There may be other combinations that work in other terminal emulators though (e.g. iTerm 2 in its default configuration arranges for Control with 2–8 generate the “non-alphabetic” control characters; this is similar to how xterm works).