#cli #calendar

bin+lib saturn-cli

saturn is a command-line interface to calendaring, supporting Google Calendar

10 releases

new 0.3.6 Sep 20, 2023
0.3.5 Sep 19, 2023
0.2.0 Sep 11, 2023
0.1.1 Sep 3, 2023

#298 in Command line utilities

Download history 31/week @ 2023-08-28 7/week @ 2023-09-04 66/week @ 2023-09-11 135/week @ 2023-09-18

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MIT license

4.5K SLoC

saturn: a calendar for CLI nerds

NOTE: all docs here chase the main branch features. If you want docs for a specific version, go to the README for the appropriate tag.

If you like the application, come to the issues list and voice your ideas and concerns. I have personally been using saturn and sui for some time alongside Google Calendar (for more complicated situations) with few issues outside of things that happen when developing software normally.

Saturn provides you with a CLI interface to calendaring much in the way taskwarrior does with tasks. It also provides you with several methods to query and notify yourself of important appointments. It can act standalone or integrate fully with Google Calendar.

Here is a demo of it in action.

Saturn is also now providing a TUI as a separate program since release v0.2.0; sui will present a calendar in a terminal window and allow you to interact with it in similar ways to saturn. See below for the list of commands.

Here is what it looks like:

Table of Contents


Install with cargo:

cargo install saturn-cli

Entry language

Entry language is basically:

ENTRY = [ "recur" <duration> ] <date> <AT | SCHEDULED | ALL DAY> ["notify" <duration>] <detail>
AT = at <time>
SCHEDULED = from <time> to <time>
ALL DAY = all day

You trigger it by using saturn entry:

saturn entry tomorrow at 8pm Take a Shower

This will schedule a shower tomorrow at 8pm with a notification at the time of the appointment. You can also use saturn e.


There are numerous formats that can be used for different times, dates, and durations. Localization is desired but I haven't found a good set of tools for doing it yet.


Dates can be represented a number of ways:

  • today, tomorrow, and yesterday are case-insensitive and have their traditional relative meanings.
  • A day (integer) by itself will assume the current month and year.
    • You can also end the day number with traditional suffixes such as th, st, nd, etc.
  • month/day (e.g. 8/7) will assume the current year.
  • year/month/day (e.g. 2023/8/7) will represent a full date.
  • The following characters can be used as date separators: /, -, and ..


  • hour:minute:second represents a full time. You may also use . for the separators.
  • hour:minute 24-hour time with the following exception: for today's date: when less than 13 represents the time in relationship to the current 12-hour clock. 13 and above are 24-hour time. You can change this behavior with saturn config set24h-time.
  • hour:minute[pm|am] represents the current 12 hour time with appropriate time of day designation.
  • hour[pm|am] represents the top of the hour in 12 hour time with the appropriate time of day designation.
  • hour represents the top of the hour in 12 hour time with the current time of day designation.
  • midnight can be used to refer to 00:00 or 12:00am
  • noon can be used to refer to 12:00 or 12:00pm.


All duration rules take from the fancy-duration crate.

Durations are combined in order of precedence with single character designations for each unit. Example: 2h15m12s, is "2 hours, 15 minutes, and 12 seconds".

  • s: seconds
  • m: minutes
  • h: hours
  • d: days
  • w: weeks
  • m (leading position only): months
  • y: years


NOTE: For Google Calendar, all listings that are unbounded time-wise have a current maximum bound of 30 days back, plus 30 days ahead. This is to ensure we grab all the results if possible in a single fetch, as well as not destroy your network each time you want to query this information for old or large calendars. saturn is not currently capable of backing up your Google Calendar.


saturn list [--all]

Will list the database for today, or if --all is passed, will list the entire db. Note that saturn today and saturn t, and saturn l are synonyms for saturn list.

saturn now [--well=<duration>]

Will list the items that need to be addressed immediately. To configure how much of a time to wrap around what "now" means, use the --well option. Durations are specified in fancy-duration format.

saturn n is an alias for saturn now.


saturn notify [--well=<duration>] [--timeout=<duration>]

Will display a notification to the screen for every item that must be addressed immediately. --well is similar to now's functionality, and --timeout configures how long to keep the notification up on the screen.

This is what a notification looks like in dunst, which the notification system for i3. GNOME, KDE, MacOS, etc will look different, but have the same text.


saturn edit [-r] <id>

Will run $EDITOR and fill it with a YAML file. When this file is edited, it will change the database and the remote side, if necessary. Specify -r for recurring task IDs.

Deletion and Mutation

saturn delete <ids...>

Will delete a calendar record by ID, which is listed with the listing tools. Pass -r to delete a recurring task.

saturn complete <id>

Will mark a task as "completed". Completed tasks get a visual notification and are automatically excluded from listing without the --all flag.

Does not work with Google Calendar.

Database & Configuration File

Saturn keeps a CBOR database in ~/.saturn.db. Locking is flock(2), and quite primitive. Suggestions and patches welcome.

The configuration file is only required in limited scenarios (such as remote calendar support) and exists in ~/.saturn.conf. It is a plain YAML file, but is typically manipulated by saturn config commands, which may replace any comments or other manipulations you previously did to the file by hand.

Leveraging the well features with a periodic scheduler

The --well options take a duration. This duration is intended to roughly match the frequency at which you run the program, so that there is little to no overlap between event firings. This flag is provided for saturn now and saturn notify.

Notifications (specified by a notify entry stanza) are only fired once in any event. Events, on the other hand, are shown every time they fall into the window, which is the current time, +/- the --well duration.

I hope this clears things up; I was trying to figure out a good way to run this in cron etc without spamming myself with notifications for a long period of time.

Here's an example: we run a loop of saturn notify with a well of two minutes, and then we sleep for a minute. This allows notify to catch the alert only once, passing it up by the next time it runs.

while true
    saturn notify --well 2m
    sleep 60

Recurring tasks

Recurring tasks start their entry with the "recur" keyword and a duration. Every time the program is run and touches the database, it will look to add recurring tasks. Recurring tasks are based off the last task that was saved, and every recurrence up to the current point will be added in the absence of them. In the Unix file implementation, (not Google Calendar, which is responsible for creating its own recurring events) until they are added, they will not have IDs nor can they be manipulated. Commands like now and notify which only perform read operations also adjust this data, so they can fire notifications properly for new tasks.

Google Calendar Support

Google Calendar support is working, with OAuth credentials being setup properly and limited control of the calendar is possible within the realm of what saturn currently supports. More is anticipated to be built atop this framework. Do not be surprised if functionality is confusing or missing. Please put in issues with your concerns, thanks!

sui also works beautifully with Google Calendar, providing a compelling, if primitive replacement for the web UI.

To use saturn with Google Calendar, you must create a Google Cloud account and assign an OAuth application to it. One is not provided automatically by using saturn to eliminate concerns of data provenance.

To do this, follow these steps, which go into how to set up an application for development. Be sure to setup any accounts you want to use as "Test Users", and ensure that https://www.googleapis.com/auth/calendar is in your list of allowed scopes. Once you have the "Client ID" and "Client Secret", run this command:

saturn config set-client <client id> <client secret>
saturn config get-token
saturn config db-type google

The get-token command will have you access a URL in your browser and make you login to the google account you wish to use, which must be listed in your "testing users" in the OAuth setup above. As a final step, it will call back into a web service the application starts, which will feed it the token.

Your token will expire if you do not use the tool regularly. Stuffing saturn notify in cron will alleviate this a bit. To get a new key, use saturn config get-token and follow the prompts. No other settings need to change.

Setting the db-type will change the source of data. If you were using a local database and want to go back to it, saturn config db-type unixfile.

Notifications setup in Google Calendar are not honored yet. This will be resolved soon!

Other things we want to do that aren't here yet:

  • Fields (URLs, Locations, etc)
  • Attendees

TUI Commands

The TUI accepts several commands at the prompt; this command-set will grow with time. To interact with it, just type and hit enter to send a command.

  • e or entry: Process an entry in saturn entry format.
  • d or delete: Delete all the IDs provided (separate them with spaces). d recur or delete recur to delete recurring items.
  • show today will show today's calendar items, where show all will show the entire calendar (the default).
  • show recur will show you recurring tasks.
  • show <id> will show you more information about that particular task. Use show recur <id> to show a recurring id.
  • edit <id> will raise an editor to edit your item's properties. edit recur <id> will edit a recurring item.
  • quit will exit the program.

Target Platform

Due to flock(2) use, which to the best of my knowledge is the only reason, Windows probably does not work properly. Patches welcome if there are windows users who'd like to use it.


Erik Hollensbe git@hollensbe.org


~1M SLoC