23 Calendar Function System

23.1 Description

The shell is supplied with a series of functions to replace and enhance the traditional Unix calendar programme, which warns the user of imminent or future events, details of which are stored in a text file (typically calendar in the user’s home directory). The version provided here includes a mechanism for alerting the user when an event is due.

In addition functions age, before and after are provided that can be used in a glob qualifier; they allow files to be selected based on their modification times.

The format of the calendar file and the dates used there in and in the age function are described first, then the functions that can be called to examine and modify the calendar file.

The functions here depend on the availability of the zsh/datetime module which is usually installed with the shell. The library function strptime() must be available; it is present on most recent operating systems.