What is CRON and What Can it Do?
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Youíve been looking for a new web host for awhile now. Youíre comparing features, prices, support options trying to find the best match for your needs. One thing that keeps popping up in some places, is something called cron jobs. What is this cron, and is it something you need?
In essence, cron is a scheduling daemon available on Linux and other Unix variants. I know this probably doesnít mean much to many of you, but donít worry, Iíll explain it better. Let's say that you own a website, and people sign up for a service you offer. But getting an email for each person that signs up is getting confusing, and some are starting to slip between the cracks. If only there was some way to make a script that would run once a day, and send you a list of that dayís subscribers!
This is why cron was invented. A web developer familiar with the workings of cron jobs could easily write and schedule a script to run once a day and email him a list of all subscribers for that day. Executing a script or program at a scheduled time is the very reason cron exists.
Cron settings are kept in a file called "crontab." This file can be edited to cause cron jobs to be executed pretty much whenever you want. To be honest, the crontab file can be pretty confusing. It is for exactly this reason that most web hosting providers only allow access to cron through an easy to use web interface.
The above is a typical cron example, available through a control panel interface. Notice how flexible the timing options are. You could easily schedule this job to run once a day, twice a day, once a week, five minutes past every hour -- just use your imagination.
So why would you ever use cron? I can tell you, from experience, that once you understand cron jobs, and use them for the first time, you will be finding new ways to utilize them to automate your workload. Over the next few pages, Iíll talk about potential uses for cron, and give some real-world examples.
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