Where I work, I often run a command that prompts me like this:

    PIN for erichan:

The current default value of comint-password-prompt-regexp doesn't hide
my typing, but I imagine it would if "PIN" were one of the elements of
password-word-equivalents.

In related news: it's surprisingly difficult to control this behavior by
simply customizing password-word-equivalents; afaict, that variable has
an effect only when comint.el loads, which appears to happen before my
custom file gets loaded.  So I've had to resort to putting this into my
init file, which makes me sad:

    ;; Setting this in custom.el doesn't work, because that gets loaded
    ;; _after_ comint gets loaded :-| And this variable's entire purpose
    ;; in life is to affect the definition of
    ;; comint-password-prompt-regexp, which is defined with a defvar, and
    ;; defvars only have an effect the first time they're evaluated, which
    ;; has probably already happened.  So we need to turn back the clock,
    ;; undefine that variable, and then re-run the defvar.  Oy gott.

    ;; Also I refuse to glom something to the end of
    ;; comint-password-prompt-regexp, that's too horrible.
    (progn
      (setq password-word-equivalents
            '("PIN" "password" "passcode" "passphrase" "pass phrase"))
      (makunbound 'comint-password-prompt-regexp)
      (load "comint"))



In GNU Emacs 26.1.92 (build 2, x86_64-pc-linux-gnu)
 of 2019-04-09 built on dev-dsk-erichan-2c-d0f79429.us-west-2.amazon.com
Repository revision: 9e865ede793adf2cc10b92889050eddb1c8f1b40
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