Create, Read, Update, Delete = CRUD

The four basic functions of any persistent storage mechanism.

Refers to all of the major functions that need to be implemented in a relational database application to consider it complete. Each letter in the acronym can be mapped to a standard SQL statement:

• Create => INSERT
• Read (Retrieve) => SELECT
• Update => UPDATE
• Delete (Destroy) => DELETE

It's really that simple and not only applies to databases but nearly any form of application.

CRONTAB and Cron Jobs

In simplest terms, a time-based scheduling service in Unix & Linux systems.

Driven by a configuration file named crontab that specifies shell commands to run periodically on a given schedule.

E.g. * Load the LighTPD web server when the server reboots