Google knows all, most of the time. However, I know I’m in trouble when I the first link returned by a search for an error message in a widely used piece of software is a commit entry adding test scripts for that and related errors to the software.
So, just in case you run into this problem where Subversion thinks you have deleted a file locally and someone has updated the same file on the Subversion server you should use the following to fix it:
$ svn resolve $ svn revert
Tell “svn resolve” to keep local changes (mc) which means the file will be deleted, and then “svn revert” will revert that delete. You’ll finally be back to a pristine work area.
Where X is the population of developers who read this blog, Y is those that use Vim and Z is those that use vimdiff regularly. I guess this post will only be useful to a tiny minority of my readers, but to them it might be the best thing they’ve read all year. (Well, it is 2016, right? It’s been a weird year.)
Vimdiff allows you to open two files in Vim and side by side compare them, pushing changes from one file to another. I’ve been using it as long as I’ve been working on b2/WordPress and even before then too. It’s supremely useful.
Over the years I’ve used many different terminals, with various settings and colour configurations. My vim settings change over time too as I move from one machine to another. Sometimes the colours look ok in Vimdiff, sometimes they don’t. Sometimes the colours are ok for one file type while conflicting in others.
The problem is that Vimdiff has it’s own colours it uses to show what parts of the files are different or missing. Those colours can sometimes hide actual text in the files. I find myself highlighting those lines with SHIFT-V to see the text.
I could pick a different colour scheme but then there’s no guarantee that a different part of text will be hidden by Vimdiff’s colour scheme. The easiest way to fix this is by disabling syntax highlighting completely when in Vimdiff and you do it like this. Open up your ~/.vimrc and add these lines:
With that in there Vimdiff goes from looking like this to the simplified appearance below.
Ironically, the theme I’m currently using in Vim in the screenshots above isn’t that problematic, but here are two screenshots that show the problem from another machine. In the second screenshot I have highlighted (with SHIFT-V) the line with the function name in the left side. As you can see, the text “function” is still invisible in the right side of the screenshot.
If you don’t want to edit your .vimrc for whatever reason you can also manually do :set syntax=off from within the editor but you’ll have to do that for each of your files.
All the code above is GPLed WordPress code. Thanks to user hildred on Stackexchange for that one. Hopefully someone else will find this useful.
A friend recently had a problem configuring a new server. He installed PHP, Apache, MySQL and phpMyAdmin but when he launched it he got the following error:
phpMyAdmin – Error
Cannot load mysql extension. Please check your PHP configuration.
If you’ve installed all of the above more than once you’ll know what is more than likely wrong. The MySQL PHP module isn’t loaded. First of all, you must find your php.ini. It could be anywhere but if you create a small php file with the phpinfo(); command it will tell you where it is. Common places include /etc/apache/, /etc/php4/apache2/php.ini, /etc/php5/apache2/php.ini or even /usr/local/lib/php.ini
Edit your server’s php.ini and look for the following line. Remove the ‘;’ from the start of the line and restart Apache. Things should work fine now!
Calling all MySQL admins! When you’re working with InnoDB tables you may have noticed that MySQL takes an extraordinary amount of time to shutdown. Don’t panic! It’s normal.
InnoDB has extensive logs that it must run through and if your server is at all busy these logs can be quite big.
After you’ve started the equivalent of “/etc/init.d/mysql stop” it may not return for quite a while. Simply open another terminal and examine the system log. On a Debian or Ubuntu box, look at /var/log/daemon.log and you’ll see the “InnoDB: Starting shutdown…” message.
Now, go off and make a cup of tea because this could take a while. On a fairly large and busy database it might be half an hour or more!
Please, please, please don’t be tempted to killall -9 mysqld because bad things will happen! Even if your boss is looking over your shoulder, and you’ve promised that the company webserver will be online in 2 minutes, don’t do it.
However, cases where it is ok to kill the database with a “kill -9”:
International terrorists are planning on robbing the World Bank and you’re the only secret agent who can bring down the database which will stop them.
Lassie will be run over by the evil farmer who plagued the local village with his monster cows unless you can corrupt his database in time.
Or finally, you like hard work and restoring from backups!
Andrew van der Stock’s criticism of PHP’s security model. What security? Global request arrays go some way to making applications safer but there are obscure functions and settings which can trip up developers. (via) PHP Optimization Tricks from Ilia Alshanetsky has one gem I didn’t know about – the ctype extension. It’s somewhat limited but would be faster and less resouce intensive than a regular expression to do simple checks.
Yes, newer browsers have SVG support but this will work in older browsers and newer. Cute.
Ever wondered how some of your favourite apps get hacked and broken into? This page lists lots of examples of database “injections”.
Like an injection you get off your doctor these bits of code inject database code into your application. The code can do anything – delete all your data, grab your passwords, or anything.
And if it happens to you, a nice doctor isn’t going to give you a lollipop.
He has a couple of examples on his page, and it looks easy enough in principle. The devil’s in the details don’t you know but it looks like it’s worth trying!
He’s a busy beaver too.. he has an MVC framework and tutorial that steps you through an example.
Among developers, design patterns are a popular way to think about design, but what is the proper way to think about design patterns? In this interview, Erich Gamma, co-author of the landmark book, Design Patterns, talks with Bill Venners about the right way to think about and use design patterns.