```

(defun ledger-accounts-list-in-file (file)

"Return a list of all known account names from FILE as strings.

Considers both accounts listed in postings and those declared

with \"account\" directives."

(let ((accounts nil))

;; Check if file exists and is readable

(if (and (file-exists-p file) (file-readable-p file))

(with-temp-buffer

;; Insert file content into the buffer

(insert-file-contents file)

;; Process the buffer content

(setq accounts (ledger-accounts-in-buffer))

(when ledger-accounts-exclude-function

(setq accounts (cl-remove-if ledger-accounts-exclude-function accounts)))

(mapcar #'car accounts))

(error "File does not exist or is not readable: %s" file))))

```

#elisp #ledger-cli #emacs #ledger-mode