Calendaring from the command line

When

When is one of the best-organized, command-line calendaring tools. The first time you run When, a wizard helps you create the ~/.when directory and its two files: calendar and preferences (Figure 4). The wizard also sets the default text editor that you will use to edit the calendar files – either the default emacs or an editor of your choice. You can change both the directory and the editor later by editing the preferences file.

Figure 4: Setting up a calendar with When.

To add an entry to When, type the command jump e (note that the "e" is a command, not an option, so it does not have a hyphen). The command opens the calendar file in the editor specified in the preferences file.

From the editor, you can add appointments one per line, in the following format, with a single space between each part:

[YYYY] [MONTH] [DAY] , [Entry].

For example:

2014 12 18 , Depart for Portland for Christmas holidays at 8:30am.

The month can be indicated by a number or any abbreviation that makes it unique, which means at least the first three letters.

If your calendar has no entries, running the when command without options prints the current date and time. However, the calendar will also print any appointments within the next two weeks, adding the day of the week to the appointment (Figure 5). Alternatively, you can specify to display appointments for the coming week (when w), month (when m), or year (when y) or print a calendar of the next three months, starting with the current month (when c).

Figure 5: Displaying calendar entries with When.

For annual events, you can replace the year with an asterisk (*). Similarly, enter a weekly event by replacing the day with w=DAY, using the first three letters of the name of the day, such as w=mon. Additionally, if you start the entry with a time using a 24-hour clock, then when will display multiple events on the same day in chronological order.

Besides these basic commands, When also includes numerous options, which can be either entered at the command line or added to the preferences file. For example, the options --future=DAYS and --past=DAYS sets the days displayed, and --ampm specifies using a 12-hour clock instead of the default 24, with a or p following the number. Other options set the number of rows and columns in which to display results, and the font weight and color for the display. The man page has a complete list of available options and preferences, although you can use When perfectly well without most of them.

Pipes and Starting Commands

When creating event entries for Calendar, Remind, and When, you can keep your calendar files readable by maintaining chronological order. However, if you forget, you can get a chronological list of events by adding the sort pipe at the end of any of these commands. The pipe will automatically print out all the events it recognizes in chronological order.

Similarly, although you should refer to your calendar regularly, you can avoid relying on a busy or preoccupied mind by setting your calendar application to run when you first log in. If you are using a major desktop, you might be able to find a configuration feature to list startup programs, such as KDE's Autostart. Another choice, if you login at the same time every day, is to piggyback your calendar on crontab. Still another alternative is to write a script, although its structure will depend on the init daemon on your system.

One concern is that none of these applications are intended for sharing calendars. If you need to share calendars, you might try gcalcli [7], which is designed to log in to Google Calendar. Although gcalcli is a command-line program, once you learn a few basic commands, it may be quicker and more responsive than using Google Calendar's graphical interface.

For strictly personal use, however, Calendar, Remind, and When are all applications that combine the philosophy of Unix (short, simple, clear, modular, and extensible code that is easily maintained and repurposed) [8] with an efficiency that the desktop sometimes loses track of. My suggestion is to start with When, the simplest of the three, then explore Calendar and Remind after you have enough hands-on experience to know what extra features you want.

The Author

Bruce Byfield is a computer journalist and a freelance writer and editor specializing in free and open source software. In addition to his writing projects, he also teaches live and e-learning courses. In his spare time, Bruce writes about Northwest coast art. You can read more of his work at http://brucebyfield.wordpress.com

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