eshell f/b

eshell-hist-dirs.el

(defvar-local eshell-hist-dirs nil)
(defvar-local eshell-hist-index 0)

(defun etc-eshell-update-hist-dir ()
  ;; prevent "cd /tmp" over and over from making new entries
  (when (not (equal (car (last eshell-hist-dirs)) (eshell/pwd)))
    (push (eshell/pwd) eshell-hist-dirs)))

(add-hook 'eshell-directory-change-hook #'etc-eshell-update-hist-dir)

(defun eshell-forward (n)
  (unless eshell-hist-dirs
    (user-error "eshell-hist-dirs is empty, cd a few times"))
  (let ((dirs eshell-hist-dirs))
    (prog1 (eshell/cd (nth (setq eshell-hist-index
                                 ;; ensure we don't go outside list bounds
                                 (if (> n 0)
                                     (min (- (length eshell-hist-dirs) 1) (+ eshell-hist-index n))
                                   (max 0 (+ eshell-hist-index n))))
                           dirs))
      (setq eshell-hist-dirs dirs))))

(defun eshell/b ()
  (eshell-forward 1))

(defun eshell/f ()
  (eshell-forward -1))

(defun etc-eshell-mode-hook ()
  ;; make sure starting directory is in history
  (push (eshell/pwd) eshell-hist-dirs))
  
(add-hook 'eshell-mode-hook #'etc-eshell-mode-hook)