Emacs: function to make a file with date/time as filename, and a shortcut for it

Question

I need to generate text files with the following name format: YYYYY-MM-DD--hh-mm-ss.org. How can I use the capture funtionality for this? That is, instead of making one entry per capture in a single file, the function should make one single file per capture, and hopefully with all the possibilities within the capture mechanism.

Answer 1

You should be able to use the function target form to do this:

(defun my/org-file-by-date ()
  "Create an Org file with current time as name."
  (find-file (format-time-string "~/org/%Y-%m-%d--%H-%M-%S.org")))

(add-to-list 'org-capture-templates
             '("x" "Template Name" plain
              (function my/org-file-by-date)
              "Capture template contents"))

Edit 2: As it turns out, code passed to a file form or the like isn't evaluated until capture time, so there's a more compact way to do this. See Erik Sjöstrand's answer for an example.

Edit 1: To get similar functionality without going through the capture interface, you can use functions similar to these.

(defun my/org-file-by-date-with-inline-skeleton ()
  "Create Org file from skeleton with current time as name."
  (interactive)
  (find-file (format-time-string "~/org/%Y-%m-%d--%H-%M-%S.org"))
  (insert "Skeleton contents"))

(defun my/org-file-by-date-with-file-skeleton ()
  "Create Org file from skeleton file with current time as name."
  (interactive)
  (let ((filename (format-time-string "~/org/%Y-%m-%d--%H-%M-%S.org")))
    (copy-file "path/to/skeleton/file" filename)
    (find-file filename)))

Answer 2

There doesn't appear to be any built-in functionality to do that (edit: yes there is, see below). The simplest solution, one that does not require delving into the internals of the capture functionality, is to bind the value of org-default-notes-file at capture time:

(defun my-org-capture-advice (func &rest args)
   (let ((org-default-notes-file
         (format-time-string "~/org/%Y-%m-%d--%H-%M-%S.org")))
    (apply func args)))

(advice-add 'org-capture :around #'my-org-capture-advice)

This advice happens very early, so it doesn't yet know which template you're going to use. If the name of the file depends on the capture template, then you'll probably need to advice org-capture-set-target-location.

Edit: the function template target is a better way to achieve that. See Aaron's answer for an example.

Answer 3

Here's a way to keep it all in the org-capture-templates list, without defining other functions. org-directory can be changed to whatever directory you want to store the files in.

(add-to-list 'org-capture-templates
             '("x" "Template name" plain
               (file (expand-file-name
                      (format-time-string "%Y-%m-%d--%H-%M-%S.org")
                      org-directory))
               "This string is inserted in the capture"))