eshell-output-filter-functions

eshell-output-filter-functions is a variable defined in `esh-mode.el'.
Its value is

(eshell-postoutput-scroll-to-bottom eshell-handle-control-codes eshell-handle-ansi-color eshell-watch-for-password-prompt)

• This variable may be risky if used as a file-local variable.

Documentation:
Functions to call before output is displayed.
These functions are only called for output that is displayed
interactively, and not for output which is redirected.

You can customize this variable.