Using Cron With AutoGallery SQL

Introduction

Cron jobs are a way of automating tasks that you want done every week/month/day and at a certain time. To accomplish this, you will make crontab entries on your server which will tell it when it needs to run the command you want. Crontab entries tell the server to "run this command at this time on this date". Using cron with AutoGallery SQL will allow you to have the software rebuild the TGP pages automatically at times you specify, and also run the gallery scanner automatically at the times you specify.

Crontab Entries

A crontab entry consists of two parts - a time to run, and a command to run.

The time to run (the first part of the entry) is broken up into 5 fields:
1. minute of the hour
2. hour of the day (on the 24 hour clock)
3. day of the month
4. month of the year (1 = January, 2 = February, etc.)
5. day of the week (0 = Sunday, 1 = Monday, 2 = Tuesday, ..., 6 = Saturday)

A * in one of these fields indicates that the job should be executed at any or every one of these, so for instance a * in the month of the year field means that this task should be carried out every month at the time specified in the other fields. A * in the day of the week field, when there is something in the day of the month field, does not mean that this task should be carried out every day, but rather that it should be carried out on the appointed day of the month regardless of what weekday it is. Only *s in the day of the week field, and the day of the month field, and the month of the year field would indicate a daily task.

Examples:
In the examples, [command] represents the full path and filename of the file you want to execute.

The job with this time to run would run every Sunday at 12:20 am:
20 0 * * 0 [command]

This job would run at midnight on any Friday the 13th:
0 0 13 * 5 [command]

You don't have to put just one time in a field. This job, for instance, would run every day at 12:30am, 2:30am, 4:30am, 6:30am, 6:30pm, 8:30pm, and 10:30pm:
30 0,2,4,6,18,20,22 * * * [command]

This one would run every Tuesday and Friday at 5:30 am:
30 5 * * 2,5 [command]

Creating a File For Crontab Entries

To register the cron commands with the server, you will need to create a plain text file with a list of all of the crontab entries. You will then use this file along with the server's crontab command to register them with the server. Once they have been registered, they can begin executing at the time you specify.

Start with an empty text file in the text editor of your preference (we recommend EditPlus for Windows users). At the top of this file you will want to put any already existing crontab entries that you have running on your server. If you have never used cron before, there will not be any. If you have used cron before, you will need to login to your server through telnet or SSH and execute the crontab -l command. This will display a list of your existing crontab entries. Copy and paste this to the top of your text file.

Now you can start adding your AutoGallery SQL crontab entries to the file. All of the available commands are covered later in this document, so be sure to read the entire thing before setting up your cron jobs.

Once you have all of the above steps completed, you can save the file. You can name it anything you want. It is recommended that you use cron.txt for the filename, however anything will work. To register these commands with the server, continue with the next section of this document.

Here is an example crontab entry file for you to look at.

Registering Your Cron Commands

Once you have created the text file containing your crontab entries, you will need to register them with the server. To do this, upload the text file to your server (for this example, assume the filename is cron.txt). A good place to upload it is the same directory where AutoGallery SQL is installed.

After the cron.txt file has been uploaded, login to your server through telnet or SSH. Change into the directory where you uploaded the cron.txt file and run the command crontab cron.txt. This will register the crontab entries with the system, and they will begin executing at the next scheduled time. To make sure your crontab entries were recorded properly, you can run the crontab -l command. This will display a list of all of the current crontab entries registered under your username.

Commands for Building the TGP Pages

Please read over the Page Building Overview section of the software manual so you understand how the page building process works

To build your TGP pages through cron, you will use the cron.cgi script. It takes one of two command line arguments, which specify what type of build you want it to do. The two command line arguments are: Here is an example of how your crontab entry might look: Note that the /full/directory/path/to/ portion would be replaced with the directory path on your server to the directory where the cron.cgi script is located.

Commands for Running the Gallery Scanner

To have the gallery scanner run automatically, you will use the scanner.cgi script. It takes a single command line argument, which is the name of the configuration that you want it to run with. Through the control panel you will need to create a configuration. This is covered in the Gallery Scanner section of the manual. Once you have created the configuration how you want it, you will use the Identifier as the command line argument. For example, say you created a configuration named 'createthumbs' which was setup to create thumbnails for galleries that do not have one. To have it run once every day, you would use the following crontab entry:

0 0 * * * /full/directory/path/to/scanner.cgi createthumbs &

Note that the /full/directory/path/to/ portion would be replaced with the directory path on your server to the directory where the scanner.cgi script is located. It is also important to have the & character at the end. This tells it to run in the background so that the server's cron system can go about it's business and not wait for the gallery scanner to finish it's task.

Other Available Commands

The cron.cgi script also accepts several other command line arguments that you can use to automate many of the software functions. Below is a list of all the available command line arguments that you can pass to the cron.cgi script. For example, if you wanted to backup your database at midnight daily, you would use the following crontab entry:

0 0 * * * /full/directory/path/to/cron.cgi --backup

Note that the /full/directory/path/to/ portion would be replaced with the directory path on your server to the directory where the cron.cgi script is located.