calendar - macOS

Overview

The calendar command in macOS is used to display information about upcoming events and reminders by scanning a special calendar file. Its primary purpose is to help users manage events important to them, which are defined in simple text files. calendar can be used both interactively and in scripts, making it a versatile tool for date-based reminders in a Unix-based environment.

Syntax

The basic syntax of the calendar command is:

calendar [options]

Arguments

calendarfile: You can specify a particular file to be used by providing its path after the options. If no file is provided, calendar looks for a file named calendar in your home directory.

Options/Flags

-A num: Display entries for num days after today. Defaults to showing today’s entries only.
-B num: Display entries for num days before today.
-t [[CC]YY]MMDD: Pretend the current date is MMDD (month-day) or CCYYMMDD (century-year-month-day).
-f file: Use the specified file instead of the default calendar file.
-a: Show all calendar entries, ignoring the date restrictions.
-w: Use week mode, which causes calendar to output calendar entries in the current week.

Examples

Here are several examples demonstrating common uses of the calendar command:

Display today’s calendar entries:
```
calendar
```
Show calendar entries for the next 7 days:
```
calendar -A 7
```
Show calendar entries from the past 3 days:
```
calendar -B 3
```
Use a specific calendar file and display entries for the next 10 days:
```
calendar -A 10 -f /path/to/custom-calendar
```

Common Issues

File Not Found: Users often encounter issues if the calendar file does not exist or is misnamed. Ensure the file named calendar exists in your home directory or specify the correct file using the -f option.
Date Format Error: Errors can occur if dates within the calendar file are improperly formatted. Ensure dates are in the correct MM/DD format.

Integration

calendar can be combined with other commands for notifications or reminders. For example, integrating calendar with mail to send daily reminders:

calendar | mail -s "Daily Reminders" your-email@example.com

This script uses calendar to fetch daily events and uses mail to send them via email.

date: Useful for getting the current system date and time, which can be used with the -t option of the calendar.
cron: For scheduling regular jobs which could include running calendar for daily event checks.

For more details on usage and additional examples, please refer to the macOS official documentation or man pages (man calendar).