The September London Joomla User Group meeting took place with less than a week to go until the only UK Joomla conference of 2011 – Joomla!Day UK 2011. Several of the speakers were at the meeting and we were given a preview of one of the talks coming up on Sunday.
Coupon code for 100% discount on your extra tickets is MAXIMUM.
Use the code for today (Wednesday 21st September) only.
Other topics discussed were getting Joomla running on a local Windows setup for development (Microsoft’s Web Matrix was recommended); the imminent release of the long awaited VirtueMart 2 – this will actually be released during Joomla Day London; a discussion about everyone’s favourite extensions; and finally we talked about making Joomla fast.
Jet Set Joomla
We asked what the fastest Joomla theme was – Afterburner from Rockettheme was suggested; honourable mentions went to Joomlapolis and Morph.
To further increase your site’s speed, use of a content delivery network was suggested – although not free, these can definitely help. If you sign up via the guy who makes the Joomla plugin there’s a discount for one popular commerical CDN.
Use Firebug for Firefox to check the download speed of all the components of your site – find out if anything is dragging your load times down.
Cron is a useful feauture on Linux operating systems that allows easy scheduling of repeated tasks. Typically this includes rotating log files so that they don’t get to big, and checking for updates to software.
Cron commands can look intimidating to the non-technical user, so this article explains how to read them.
A typical crontab line looks something like this:
The asterisks at the beginning of the line are the all important timing information.
The values accepted for each field are: The minute field value must be 0-59, the hour field 0-23, the day of month field 1-31, the month field 1-12 and the day of week field 0-6 (Sunday is 0 but this can also be given as 7).
The values can be given in a variety of formats:
- An asterisk (*) character will match all possible values for the field: e.g. the Cron expression “* * * * *” will run the command every minute since this is the smallest representable time period.
- A literal value: e.g. “30 * * * *” will run the command whenever the minute is 30, i.e. once an hour at half-past the hour.
“* * 5 * *” will run every minute when it is the 5th day of the month.
- A list is given by separating each possible value using a comma: e.g. “0,15,30,45 * * * *” will run the command whenever the minute is either 0, 15, 30 or 45. Another example, “0 1,2,3 * * *” will run the command between 1am and 3am (inclusive) but only when the minute is 0, i.e. on the hour. Lists can also contain ranges (see below).
- A range is given by separating the lower and upper values of the range with a hyphen (-): e.g. “0 1 1-5 * *” will run the command at 1am on the first, second, third, fourth and fifth days of the month.
- An increment is given by using a forward slash: e.g. “*/15 * * * *” will run the command every 15 minutes starting on the hour. i.e. this example is the same as the list example given above to run whenever the minute is 0, 15, 30 or 45.
- A final example “35 7 * * *” means run the command at 35 minutes past 7am, everyday.
By default each run of the command will write to your log file. A couple of options are to change this:
- Add “>> /dev/null 2>&1” to the end of the command line (a space then the text inside the “)
- Add “| mail -s “Subject” email@example.com” to send a confirmation by email.
Ready to have a go?
This utility helps you build Cron expressions easily by choosing job scheduling scenarios. The crontab entries produced work with Vixie Cron, popular in many Linux distributions.
In the examples above, you should normally remove the inverted commas (“) around the commands.
If you need any advice about cron, we’ll be happy to help. Please contact us.