To combine two images of the same size with ImageMagick, you simply do the following:

The following will overlay overlay.png on top of output.png

mogrify -draw "image SrcOver 0,0 0,0 'overlay.png'" output.png

While this one will overlay overlay.png on top of input.png and save it as output.png

convert input.png -draw "image SrcOver 0,0 0,0 'overlay.png'" output.png

You can download imagemagick from http://www.imagemagick.org/

Selective colour replacement is easy from the command line with imagemagick.

You can download imagemagick from http://www.imagemagick.org/

The following will replace all red (#FF0000) pixels with blue (#0000FF)

convert sourceimage.png -fill "#FF0000" -opaque "#0000FF" destimage.png

I needed recursively delete folders named .svn within a directory structure.

The following will allow you dto do this from a command prompt:

FOR /F "tokens=*" %G IN ('DIR /B /AD /S .svn') DO RMDIR /S /Q %G

Remember, if you’re doing it from a batch file, you’ll need to double up the percent signs, thus:

FOR /F "tokens=*" %%G IN ('DIR /B /AD /S .svn') DO RMDIR /S /Q %%G

So, you want to set up a write only ftp directory on IIS? One where you can upload files, but not list them?

Easy…
(more…)

I’ve been doing some performance tests on WordPress to see how much of a difference the WordPress Super Cache plugin made.

It turns out that the plugin makes a huge difference. (more…)

So, you’re using sendmail to try and send emails from php/wordpress and it’s not working?

Are your mail logs (/var/log/mail.log) showing nrcpts=0 ??

Make sure the sendmail_path in your php.ini file (/etc/php5/apache2/php.ini) is set up correctly.

It should probably be…

1

sendmail_path = /usr/sbin/sendmail -t -i

This page has the permalink http://www.john.geek.nz/2010/04/wordpress-permalinks-and-404-errors But internally its default URL is http://www.john.geek.nz/?p=1495.

Permalinks help people see the topic of a page before it’s visited and generally mean that search engines will rank them higher too.

OK, so you’re getting 404’s as soon as you enable permalinks other than the default?
(more…)

I’ve taken the plunge, and this time I’m not doing it by halves.

I’m moving from my Windows Server 2003 physical co-located server to a Virtual Private Server (VPS) running Linux.

All of the websites have been transferred across, everything else is still to be moved over.

In the meantime, if you find any problems, or anything 404’s, please flick me an email at b…@john.geek.nz

I’ve been using DateTimeUTC for quite some time in batch files to get a nicely formatted date.

This is the first major revision of DateTimeUTC where you can now add or subtract from the current date. This is very useful if you want yesterday’s date.

Get the latest version from here: DateTimeUTC

The main usage of the application is:

datetimeutc [-options]

Options:
-fFORMAT Set output format
-z Set output time to Local Time (Not UTC)
-help View full online help

Example formats:
yyyyMMddTHHmmssZ 20081121T100227Z
“yyyy-MM-dd HH:mm:ss UTC” 2008-11-21 10:02:27 UTC
“dd MMMM yyyy” 21 November 2008
ddd Fri
dddd Friday
fff (Milliseconds)

Use double quotes when the format includes a space
Use backslashes to escape reserved character

Now, to add or subtract from the time, the format of the option is:
-[timeunit][value]
[timeunit] is one of YMdHms for Year, Month, Day, hour, Minute or Second
[value] is an integer and can be positive or negative

The following will print the UTC time one day ago:
datetimeutc -fyyyyMMddTHHmmssZ -d-1

Do get the output into a batch file, try this:
for /f “usebackq” %%a in (`datetimeUTC.exe -fyyyyMMddTHHmmssZ`) do (set UTCdts=%%a%)
echo %UTCdts%

Job done

I’ve recently come across the open source software Xplanet, which will render images of the globe with very realistic results.

I render them in 512×256, 1024×512, 2048×1024 and 4096×2048 resolutions. The clouds information is obtained from weather satellites and is typically around three hours old.

I also use monthly map files so that the snow/ice on the planet is more realistic.

Check out my real time renders at http://www.john.geek.nz/earth/.