I'm signing up with Aletia.com to use the cron job feature. But how do cron jobs work? You make a script (like in php) and you tell the system to run this script every day at 12:00am? Is it that simple?

in a word, yes. you make a script in any number of languages (including php if the php cgi is installed) and schedule it to run at a certain time of day (there are other options as well, but this is one of them).

Chris

Here is the way to run it, depending on your system log in the do a 'crontab -e' edit it and the save it and it installs automatically.

# minute hour day month day of the week script to execute
# (0-59) (0-23) (1-31) (1-12) (0-6 with 0=Sunday) (executable)
#
0 0 * * * /path/to/your/script

To create a cron for a user, log in as the user.

1) su $user
2) crontab -e
3) min hr date mon day /home/$user/$domain-www/path/to/script
where

min - minute (00 - 59)
hr - hour of day (00 - 23)
date - day of month (01 - 31)
mon - month of year (01 - 12)
day - day of week (00 - 06)

4) save changes
5) exit

However where you want a script in php to work you have to put in a little more.
Here's the instructions when php runs only as an apache module

Say you are user star and you want to run a php program(say http://www.star.com/exp.php) from cron and output the results to a file /home/star/phptest2

Telnet into the system as star
create a file (say /home/star/cronjob)
Add the folllowing lines to it



SHELL=/bin/bash

MAILTO=star@starinc.com

0 * * * * /usr/bin/wget -O/home/star/testphp2 http://www.starinc.com/exp.php

The above syntax means that at the start(0) of every hour(*) of every day(*) of every month(*) of every year(*), wget will run the exp.php and output the contents to testphp2. And when this runs, it will send a mail to star@starinc.com
Save the above file
now run crontab /home/star/cronjob
This will automatically add it to cron and execute it at the designated time
If you do not want to output the results anywhere simply omit
-O /home/star/testphp2

To view the contents of cron simply type crontab -l
to remove tasks from cron simply type crontab -r



Say you are user root and you want to run a system critical php program(say http://www.starinc.com/exp.php) every hour from cron and output the results to a file /home/star/phptest2 here's what you do

ssh into the system as root
create a file say( /etc/cron.hourly/phpcron)
Add the folllowing lines to it



#!/bin/sh

/usr/bin/wget -O/home/star/testphp2 http://www.starinc.com/exp.php
save and chmod to 755
Here cron automatically reads /etc/crontab , detects all scripts in /etc/cron.hourly (in our case phpcron) )and executes them
For hourly , daily, weekly and monthly, store your scripts in /etc/cron.hourly, /etc/cron.daily, /etc/cron.weekly, /etc/cron.monthly respectively


I hope this helps.
Have a great day :)

Regards
Amar

how do you start a cron job every 10 minutes?

Regards
Michael

Originally posted by MikeMike
how do you start a cron job every 10 minutes?

Regards
Michael

You can specify multiple minutes, hours, days, etc in cron jobs using the comma. For example:

0,10,20,30,40,50 * * * * /path/to/10minscript

Will run the script /path/to/10minscript every 10 minutes. So long as you don't put a space between the minute values you are OK.

Take care,

Brian