Website automation can be really helpful to your website. Whether its backing up (which you definitely will need) or running a script to update an sql database, you'll need crontab. In this tutorial I will show you what crontab is, how to use it and an example to backup a database with it.

Crontab is a *nix program that is used run commands at specific times. Ok, lets begin:
Type crontab -e
You should get something similar to this:


Ok now type 'i' and input something similar to: 30 * * * * /home/virtual/site/fst/var/www/html/cron.php. You should get something like this:


Now push Escape then type :wq (it tells it to write the changes and then quit)
It should say 'installing new crontab'
Now to view your crontabs you can type crontab -l

Ok so what did we just do?
We set up a cronjob that will run the script cron.php every 30 minutes and output nothing. Here is a summary of the fields:


(note the * means all)
Now for one that will run once a week at 1 AM

0 <- tell it to run on 0 minutes
1 <- run at the first hout
7,14,21,28 <- run at intervals of 7 seven days
* <- all months
* <- all days of week
/home/virtual/sitee/fst/var/www/html/cron.php <- command
> /dev/null <- what to output (nothing in this case)

Ok now lets create an example cron job, it will be a script that runs once a day and will backup our database.
We'll use

php:

---

#!/usr/bin/php -q
<?php
$user = "username";
$pass = "password";
$db = "dname";
$path = "/"; // where to back up files

$file = $path."backup-".Date("m-d");

@exec("mysqldump -u '".$user."' -p".$pass." --opt ".$db." > ".$file.".sql");
?>


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