Day by day, things are becoming more automated and computers are helping us schedule our routine tasks so that we can put our minds to something more useful. Since timing is critical, we need to ensure that our tasks are done when and how needed, without having to intervene. In an eCommerce business, whether the webmaster is asleep or on vacation, the website is up and live. What keeps all of this ticking? How are invoices, reminders, alerts, reports and automated tasks processed? This article takes you into the world of the Cron Job which is a tool to schedule your daily web hosting tasks on a Linux server.
Cron Jobs are basically just a system of scheduling Linux commands, so that you can automate certain tasks or run certain commands at a future time, without human intervention. To use a cron job, you need to know how to execute Linux Commands in the Linux command line. All that a cron job does is to schedule those commands so that they are timed.
Cron jobs can be used to run individual commands or to run multiple commands in a shell script. Instead of setting up multiple cron jobs, you can consolidate all your commands to be executed at a single time. Cron commands follow a specific syntax or nomenclature and hence have to be setup accordingly. Although it is very easy to setup the scheduling of commands, it is best to consult your programmers and do a couple of tests before using it in a live environment.
Web Hosting Control Panels usually have a Graphical User Interface for users to setup a cron job. This simplifies the process and avoids use of the command line and helps the user by providing preset schedules or assisting in formatting the syntax for the commands. It also allows the web host to allow users to setup crons without giving them command line access. The GUI also validates the commands for any errors and prompts the user as to what should be put in. On the other hand, some users may want to insert cron jobs through the command line itself. Some web hosts allow limited jail shell access to the linux command line, but most of them do not allow it.
Cron Jobs are used extensively for email alerts, billing, reminder systems and even system administration. Web hosts, eCommerce websites and even web apps use cron jobs or scheduling systems to generate invoices, send out reminders, renew services, initiate billing and also calculate resource usage on a daily basis. Ecommerce platforms use it for billing reminder scheduling and for calculating invoices from date to date. Calendar services use scheduling systems to trigger email or SMS alerts to their users. System Administrators may use it to generate server reports and inform users of their disk space and bandwidth usage. Programmers may use it to generate data on website performance or to simulate activity on a website or even to clear cached files or logs in an account. Software providers use it to check for updates of their software on a nightly or daily basis. Webmasters may also use them for taking backups or pruning large files.