Automatic Publication at Scheduled Times (Cron job)

Introduction

One situation is that you have allowed various users to upload files into the relevant directory (category) and these need to become Downloads.  But you do not want to grant access to the backend to allow those users to run the monitoring. 

Another situation is that you need to create a large number of Downloads.  These could have been setup on a test site and now you want to upload and publish them.

Transfering a large number of files in a directory structure from your PC to your website is readily achieved using your an ftp program such as FileZilla.  These downloads, and possibly new categories, will need creating into Downloads and publishing.

Doing this automaticly on a scheduled basis is known as a 'Cron job'.

jDownloads Options

Before doing anything else you need to look at the settings in the Monitoring section of the jD Options.  These include  'Monitor all file types', 'Monitor All Folders' and 'Automatically publish new found items'.  So set those up first to suit your current needs as they will be used by the monitoring.

If 'Monitor all file types' is set to No then another option becomes available that allows you to specify file types.

Similarly if 'Monitor All Folders' is set to No then further options allow specifying which Categories are to be included or excluded.

For more details on the Monitoring options please see the article Monitoring Options and Checking the Download Area (opens in a new window/tab).

If you, as the administrator, are initially copying over large number of files you probably would set "Automatically publish Downloads?" to Yes.  But later if you open it up to some general users then you may wish to review each Download before publishing it by setting "Automatically publish Downloads?" to No.  That is set it to whichever way suits your current needs.

This is not always convenient. A solution is to have the scanning scheduled to run periodically or at some fixed time from your web site services.  Such a facility is often referred to as a 'Cron job'.

Cronjob Command

A cronjob or similar is actually  a way of executing a php script on your web site at periodic intervals.  Adding new categories and Downloads require a  'command' to the existing scan.php script.

This 'command' will include what is known as the 'key' as a security check.  The form of the command is:

"https://<your-site>/administrator/components/com_jdownloads/helpers/scan.php?key=this-is-a-key&mode=0&test=0"

where the key part is unique to your specific  site. 

This secret key, this-is-a-key, is the one created by Joomla! for your site.  It may be found in the Joomla! System - System Information - Configuration tab. Scroll down until you find the Secret key.  It is usually a 32 character sequence such as for example say 'stoAs118BoemlusWO1mlaxoesPl9wrlU' - (this example secret key is artificial and not real).  With this secret key the fullversion of the command would look like

"https://<your-site>/administrator/components/com_jdownloads/helpers/scan.php?key=stoAs118BoemlusWO1mlaxoesPl9wrlU&mode=0&test=0"

However as the default values for mode and test are zero then the following command, which is compatible with the one used in jD 3.2 series, will also work:

"https://<your-site>/administrator/components/com_jdownloads/helpers/scan.php?key=stoAs118BoemlusWO1mlaxoesPl9wrlU"

jDownloads compares the key supplied in the command with the one in your Joomla! configuration file so that no one else can initiate a Cron on your site.

scan.php settings

Actually you can control what actions scan.php will take by setting the mode as shown below.
   (a) &mode=0 : do all (default setting)
   (b) &mode=1 : only search for new Categories
   (c) &mode=2 : only search for new Files
   (d) &mode=3 : only check existence of Categories
   (e) mode = 4 : only check existence of Files

The value of test should always be 0 that is &test=0

Using cPanel Cron job

Most cPanel implementations have an Advanced section with a Cron job icon, such as cron icon.  Clicking on it takes you to the setup page.

These notes apply to cPanel version 88.0.33 but all recent versions are very similar.

The cPanel has the ability to send an email every time the cron job runs. 

You just  put in your email address into the appropriate field. 

You can either use the current email or select a new one.

If you have multiple cron jobs there is a way of selectively setting which cron jobs will not send an email.



cron job12
After scrolling down  a 'setup' view such as shown opposite appears.  If you leave it blank then no emails are sent. 

Setting up the schedule times for the cron to run is reasonably simple. 

The easiest way is to use is the common settings which can be readily adjusted in the  individual time parts. 

In the example shown opposite the schedule is twice a day at 00 and 12:00 on every day.  

One could edit the hour part to say 1 and 5 to give an unequal spacing.

The Command part is simply
"https://<your-site>/administrator/components/com_jdownloads/helpers/scan.php?key=your-key"

where your-key is the Joomla! Secret key specific to your site (see System - Site Information - Configuration tab Secret field), and the <your_site> is replaced by www.yoursite.com as appropriate.
Cron04C2


After clicking on the 'Add New Cron Job' button a line appears something like opposite.

Cron04D2
The resultant schedule and command are quite obvious.  Importantly one is able to edit the 'cron line' to change say the schedule.  For initial testing setting I set the cron job to run every five minutes with just a few files.  It was then edited to run just twice a day.

If the cron job does not run then you should initially check with yout host site provider as they may have imposed some restricions such as a minimum time interval.

Joomla! Extensions for Cronjobs

At the time of writing there are no 'self-contained' cron job  Joomla! extensions.  There are some that are incorporated in other applications, for example Komento.

There are also some such as jPrc  and No Boss Cron which have an effective way of simulating a cron job.

Web based Cron Jobs

Another alternative is to use a web based cron service. There are a whole host of services, many free.

To find some try searching with a phrase like 'cron services'.

They just need to know the url of the jDownloads scan software and of couse the frequency at which a scan is to occur.

Some free ones require you to renew every month.

But there are others such as https://cron-job.org/  that allow you permanent access.

Setup is simple as illustrated opposite. 

There are also some additional options about email notification should a cron job fail.
cron job02

Background Notes

Any Cron job consists of two parts: the scheduling time string, and the command which eventually get combined.

The time string is made up of 5 items specifying: minutes, hours, days, months and weekdays.  The syntax is five space separated 'values'; but the values not always obvious!

Some examples are given below but if you want to determine other time strings then you could look at https://crontab-generator.org/ .   All times are usually UTC based so you may need to take that into account.

Time string  */30 4 * * * would cause execution every day at 4:00 and 4:30.
Time string     3 4    * * * is once a day at 4:03 am
Time string  */20 * * * * is every 20 minutes

The general structure of the command part for use with jDownloads is the unix command: "curl -s /dev/null https://websitename/script-name"

Specifically something like:
curl -s /dev/null  https://<your_site>/jda1/administrator/components/com_jdownloads/helpers/scan.php?key=qwertySS1zW0kIdQ1VZ7xxxyyy
which also includes the Secret key specific to your site as described above. The  key shown is  of course not a real one!

Colin Mercer July 2019, updated August 2020

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