Daniel Liden

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Task Repeaters in Org Mode


I recently started using org-mode to keep track of a few habits (morning meditation, getting some sunlight and exercise before my morning coffee, etc.) and needed to make use of org-mode's calendar features to do so. I've previously set deadlines and scheduled dates for my TODO entries, but have seldom used repeat intervals. My early attempts ( date +1d) worked fine but required some extra steps if I ever missed a day. This post discusses the .+ and ++ -style repeat intervals, which allow more control over what happens when you complete a task after the scheduled date.

Review: Dates, Schedules, and Deadlines in Emacs Org-Mode

The org-mode manual provides plenty of details on the basics of dates and times. Here's a quick review:

  • Add a timestamp with only the date to an org-mode entry with <C-c> .. A timestamp entry with a time can be added with <C-u><C-c> .. While there are plenty of methods for modifying timestamps after creation, I typically create the timestamp and then modify it, if needed, with S-LEFT/RIGHT/UP/DOWN to change the day (forward/back) or whichever element of the timestamp the cursor is located on (up/down).

    Another useful timestamp format is <C-c> ! (org-time-stamp-inactive), which inserts an inactive timestamp (represented with square rather than angled brackets; e.g. [2022-01-16 Sun] rather than <2022-01-16 Sun>). Inactive timestamps work the same as active timestamps, except that they do not appear on the org-agenda.

  • Two timestamps connected by -- make up a range (e.g. <2022-02-12 Sat>--<2022-01-16 Sun>). A range will appear on the agenda on the start and stop dates and on all dates in the range.
  • Add a scheduled date to a headline with <C-c><C-s> and a deadline with <C-c><C-d>. Again, there are plenty of details in the manual. Both of these types of timestamps affect how the timestamp appears in the agenda. In short, a "scheduled" headline appears on the date of the timestamp and on every day following until the entry is marked DONE. A "deadline" timestamp on a headline will start appearing in the agenda org-deadline-warning-days before the deadline timestamp and will appear daily until it is marked DONE.

    Conceptually, a "deadline" in org mode comports with the common use of the word: it is the date when a task is supposed to be finished. The meaning of "scheduled," on the other hand, specifically refers to the date when a task is to be started. It is not meant to be used in the sense of "scheduling an appointment." A regular timestamp is better suited for this use. Recall: a scheduled headline will appear in the agenda even after the scheduled date, which is not especially useful for an event (again, like a meeting or appointment) that occurs on a given date.

Repeat Intervals

Org-mode makes it possible to schedule recurring events without manually specifying each repetition date. There are three key formats for repeated events. Regardless of the format, the main idea is to add a repetition interval to the timestamp. A repetition interval combines a number with a unit of time to specify how often a timestamp/schedule/deadline should be repeated. For example:

  • <2022-01-16 Sun +1d> will repeat daily.
  • <2022-01-29 Sat +5d> will repeat every five days.
  • <2022-01-29 Sat +1y> will repeat yearly.

When specifying repeat intervals, y means "yearly", m means "monthly", w means "weekly", d means "daily", and h means "hourly." Prepending these values with +<number> tells how often the event should be repeated.

Different Types of Repeat Intervals

Here's where I ran into trouble. I scheduled some events as daily "habits." For example, I wanted to take a walk each morning, so I included the following in my planner file:

* TODO Walk 1000 steps before coffee
SCHEDULED: <2022-01-29 Sat>

The idea was that, each morning, I would take a walk and mark the task as DONE, at which point the date would advance to the next day. This worked fine for a while, but eventually I missed a day. Suppose I was supposed to walk on <2022-01-25 Tue> but, instead, I got up and immediately started working on my computer. Before I knew it, it was after noon and I'd only walked between the coffeepot and the computer. But I didn't give up, and I took a morning walk again on <2022-01-29 Sat>. Here's what happens on <2022-01-29 Sat>:

State before marking DONE:

* TODO Walk 1000 steps before coffee
SCHEDULED: <2022-01-25 Tue +1d>

State after marking DONE:

* TODO Walk 1000 steps before coffee
SCHEDULED: <2022-01-26 Wed +1d>
:LAST_REPEAT: [2022-01-29 Sat 09:11]
- State "DONE"       from "TODO"       [2022-01-29 Sat 09:11]

The scheduled date advances by one day, but that day is still in the past. If I really, really need to account for every day, maybe this is what I want. I could fill out the rest of the days between 2022-01-25 and 2022-01-29 for the sake of completeness. But oftentimes, if I don't mark something as done, it's because I haven't done it. I want to indicate that I completed the task today and I plan to complete the task again tomorrow.

There are two special repeaters for situations like this.

The .+ Repeater

Instead of scheduling with +1d, we can use .+1d to specify that, after we mark a task DONE it should advance by exactly one day from the date (and time, if the timestamp includes a time) when we marked it DONE. Let's walk through an example. Let's say I was supposed to clean the kitchen on Sunday, January 9, and weekly thereafter. But suppose I didn't get to it until Saturday, January 29.

State before marking DONE:

* TODO Clean the Kitchen
SCHEDULED: <2022-01-09 Sun .+1w>

State after marking DONE:

* TODO Clean the Kitchen
SCHEDULED: <2022-02-05 Sat .+1w>
:LAST_REPEAT: [2022-01-29 Sat 09:28]
- State "DONE"       from "TODO"       [2022-01-29 Sat 09:28]

A couple of noteworthy things happened here:

  • The next scheduled date advanced to a future date one week from the LAST_REPEAT date.
  • The next scheduled date did not schedule for the next Sunday but for the date one week from when it was marked DONE, a Saturday.

The ++ Repeater

The ++ repeater is very similar to the .+ repeater insofar as it will also advance the scheduled date into the future. However, it will also match the original scheduled time and day of the week. Here's the previous example, updated to use the ++ syntax.

State before marking DONE:

* TODO Clean the Kitchen
SCHEDULED: <2022-01-09 Sun ++1w>

State after marking DONE:

* TODO Clean the Kitchen
SCHEDULED: <2022-01-30 Sun ++1w>
:LAST_REPEAT: [2022-01-29 Sat 09:35]
- State "DONE"       from "TODO"       [2022-01-29 Sat 09:35]

It is now scheduled for the next Sunday (even though that's only one day after the LAST_REPEAT date). In other words, it will always advance into the future, but it will match the scheduled day of the week instead of advancing the scheduled date exactly be the repeat interval.

One consequence of this behavior is that the next SCHEDULED date might be less than the repeater interval in the future relative to the LAST_REPEAT date. For example, if I schedule cleaning each Sunday, but I don't get to it until Wednesday one week, the next repeat will still be scheduled for the following Sunday, only four days later.

Marking Tasks with Repeaters DONE (For Good)

You may want to end a repeated task—stop it from appearing in your agenda and mark it DONE —without entirely deleting the task. Maybe you want to maintain the task history or re-activate the task in the future. There are two approaches to this.

  1. Mark the task as DONE by invoking the org-todo function with the numeric prefix of -1. You can do this with:
    • <C-u> -1 <C-t> or <C--1><C-t>, or
    • <C-u> org-todo or <C--1> org-todo, and then changing the state to DONE. (<C--1> means to hold Control and type -1).
  2. Deactivate the timestamp. Org will not repeat inactive timestamps. You can do this by placing the cursor on one of the angle brackets <,> on either side of the timestamp and pressing the up arrow. This will change the angle brackets to square brackets, indicating an inactive timestamp.

Further Reading

The org-mode manual is the best place to learn more about timestamps, schedules, and deadlines in general and repeated tasks in particular. Here are some places to start:

Date: 2022-01-29 Sat 00:00

Emacs 29.3 (Org mode 9.6.15)