This simple command-line utility is designed to generate an iCalendar event, and sending it out as an email to the attendees.

It is written out of my frustration that very few applications allowed me to very quickly generate a simple and clean iCalendar event file (.ics), which I can attach and email out to the attendees.

For example, I can try to produce such an event file in the Calendar app in macOS, but once I need to add a few attendees, the app will force me to send invitations out before I am allowed to save the event file. To make the process even more cumbersome, the attendees are required to be in the Contacts app, and the only way to save the event file in Calendar is to mail the event and then save the attachment.

As another example, while Google Calendar is able to construct the event and send an email message to the attendees, the From address of the invitation email is not configurable and must be a gmail.com address, and the content of the message is also not configurable.

Instead of using calendar applications such as Calendar and Microsoft Outlook, this utility generates a single event as an iCalendar file (.ics). Most information, including a summary (title) of the event, its location (multiple lines are allowed), its date and time, the names and email addresses of its attendees, can be entered when running this utility.

The name and email address of the organizer, the default timezone, as well as the number of minutes before the event when a default alarm will be displayed, can be read from a configuration file in YAML format. The default location for this configuration file is ical.yml in the same directory.

Once the iCalendar event file has been generated, the utility will send it out as an attachment automatically to all the attendees if needed. The subject of the outgoing email message is the same as the summary (title) of the event, and the content of the email message can be composed on-the-fly when prompted. In order to send an email using an existing mail server, the domain name, username, and password of the mail server need to be added to the configuration file (ical.yml).

Mailing lists can be used by entering the name of the .csv file (without the .csv suffix). For example, if we wish to use a file called baochun-group.csv, we would enter baochun-group when prompted for the name of the mailing list. The file will contain a spreadsheet in comma-delimited format, with the first column containing the names of the attendees, and the second containing their email addresses.

Note: If you are trying to use certain mail servers (such as gmail.com) to send emails from Python, you may need to generate an app-specific password. For gmail.com, you may also need to allow less secure apps in your account.

To install the dependencies in your Python environment, run:

pip install -r requirements.txt --upgrade

To upgrade Python packages in an existing Python environment, run:

python upgrade_packages.py

To run the utility:

python ical.py

Enjoy!