Elisp: Get User Input

This page list ways to get user input.

Ask for File Name

read-file-name

Ask user to give a file name.

(defun ff ()
  "Prompt user to enter a file name, with completion and history support."
  (interactive)
  (message "String is %s" (read-file-name "Enter file name:")))

Try it. You'll have file name completion feature. Pressing ↑ will show previous file name you used.

Note, many query user input commands support command history. Command history means, user can press ↑ key to use previous input. (e.g. Alt+x shell-command) Also, some commands provide name completion (e.g. Alt+x dired).

Ask for Directory

read-directory-name

Ask user to give a directory name.

(defun ff ()
  "Prompt user to enter a dir path, with path completion and input history support."
  (interactive)
  (message "Path is %s" (read-directory-name "Directory:")))

Ask for String

read-string

Ask user to type a string.

(defun ff ()
  "Prompt user to enter a string, with input history support."
  (interactive)
  (message "String is %s" (read-string "Enter your name:")))

Ask for Regex String

read-regexp

Ask user to type a regex.

(defun ff ()
  "Prompt user to enter a elisp regex, with input history support."
  (interactive)
  (message "Regex is %s" (read-regexp "Type a regex:")))

The most general command is read-from-minibuffer. All the above are implemented on top of it.

(info "(elisp) Minibuffers")

Ask for Number

read-number

Ask user to type a number.

(defun ff ()
  "Prompt user to enter a number, with input history support."
  (interactive)
  (let (n)
    (setq n (read-number "Type a number: " 10))
    (message "Number is %s" n)))

Select from a List

The best way to ask user to select from a list, is by ido-completing-read.

(require 'ido)

(defun my-pick-one ()
  "Prompt user to pick a choice from a list."
  (interactive)
  (let ((choices '("cat" "dog" "dragon" "tiger")))
    (message "%s" (ido-completing-read "Open bookmark:" choices ))))

Query User for Yes/No

y-or-n-p

Ask user a yes or no question. Return t if user types “y” and nil if user types “n”.

(if (y-or-n-p "Do it?")
    (progn
      ;; code to do something here
    )
  (progn
    ;; code if user answered no.
  )
)

(info "(elisp) Yes-or-No Queries")

Get User Input as Function's Arguments

Elisp: Interactive Form

Get User Input from universal-argument

Elisp: Get universal-argument