On Sun, Aug 21, 2011 at 10:01:24AM -0600, Paul Gilmartin wrote:
> (Damn! I clicked the wrong link in the confirmation notice.
> Apologies.)
> 
> For some time now, on both Ubuntu and Cygwin, "set -o vi"
> is ineffective.
> 
> The command is accepted and a query indicates it's in effect:
> 
> \! $ uname -a
> Linux Linux-Mac 2.6.38-11-generic #48-Ubuntu SMP Fri Jul 29 19:05:14 UTC 2011 i686 i686 i386 GNU/Linux
> \! $ set -o vi
> \! $ set -o
> Current option settings
>     ...
> vi              on
> emacs           off
>     ...
> 
> But when I press ESC to enter command history, it simply
> echoes the ESC as "^[" and calls the next command illegal:
> 
> \! $ ^[
> dash:  not found
> 
> Thanks,
> gil

I think this requires dash to be built with libedit support to work.
Check your packages.

Regards,
-- 
# Petr Sabata