Hello Lars,

As you've mentioned, parsing ( and prompting ) is not done, when
command is sent directly to shell. But, i think
'eshell-invoke-directly' should not have returned true for sudo and
su. Comment section in 'eshell-find-alias-function' best describes it,

(defun eshell-find-alias-function (name)
 ...
    ;; If the function exists, but is defined in an eshell module
    ;; that's not currently enabled, don't report it as found.

eshell-tramp is disabled by default. So, eshell-invoke-directly should
return nil for su and sudo ( I'm new to eshell as well. So, I might be
wrong here ). Replacing fboundp with 'eshell-find-alias-function'
should fix this. So far, I've tested locally and it is working fine.

Patch attached.

Regards
Ruthra Kumar