While playing with my /etc/hosts file for testing a new server setup I needed to flush my DNS cache. As ever, terminal came to my aid.

dscacheutil -flushcache

Now all is well in the world of DNS.

The last couple of days I’ve been thinking about setting up a local copy of my websites on my laptop so that I can develop them before I make them live.

Last night I enabled PHP on the apache server built into Mac OSX on my new laptop and installed MySQL on it. I also set up some bash aliases to rsync commands so that I could synchronise the websites from the server to the laptop and back again.

Now that I had local copies of the sites that are synchronised it was time to turn my attention to synchronising the databases between the server and my local machine. I could of configured the server’s MySQL installation to allow remote connections, however, I did not want to do this for security reasons. I decided that I would connect to the MySQL server over SSH by forwarding a port on my local machine to a remote port on the server.

First I needed to create an SSH tunnel using the following command

ssh -fNg -L 3307:127.0.0.1:3306 server.host.name Read the rest of this entry »

At the beginning of the week I purchased a new MacBook Pro In between working I’m in the process of configuring it as I like it and one of the things that was bugging me was the default shell for the root user. I was foolishly trying to set the the prompt PS1 value in .bash_profile when the default root shell isn’t even bash.

The solution is to switch to the superuser (root) and issue the following command…

chsh -s /bin/bash

That will change the default shell to bash and the prompt will change as per your configuration.
Just for information my root PS1 is…

PS1=’\[\033[01;31m\]\h\[\033[01;34m\] \W \$\[\033[00m\] ‘

Happy Configuring!

Recently I’ve had a bother with the Mac firewall asking me if I want it to accept incomming network connections every time I open a particular application.

The appropriate setting can be found under:

System Preferences : Personal > Security > Firewall

I have mine configured to “Set access for specific services and applications” which normally asks me if I want to allow an application to accept incoming connections the first time I run it and that’s normally the end of it. The trouble comes when you try and update certain applications using Software Update. I’m not exactly sure what causes the problem but for some reason with specific applications the firewall then proceeds to ask you, each time, if you would like it to accept incoming network connections. This you can imagine is superlatively tedious.

The answer though is to just delete the application from you applications folder and reinstall it. The first time you open the freshly installed application it will ask the question and then bug you no more. Then all you have to worry about is not updating it via software update again.

If you’ve ever used the great GNU Image Manipulation Program, GIMP, on a Mac then you’ll no doubt have been frustrated with the way X11 seems to handle window focus. Fortunately there is a solution and its just a couple of simple terminal commands away…

When selecting tools from their dialog in GIMP on your Mac then you are required to click once to give that window focus and again to actually select the tool you require. The same two clicks are required again to actually use your tool.  You can either imagine or know first hand how annoying this becomes and its a shame for such a great piece of software to be blighted by this issue so lets fix it.

Firstly you’ll want to open your terminal (who could live without it… mine’s almost always open!). Then you want to enter either of the following commands depending on whether you’ve got XQuartz updates (and if you’re not sure just do both sets).

Read the rest of this entry »

Ctrl + D

Ctrl + U

I’ve been working on some sites locally on my Mac but by default the files are stored in a directory in the individuals user account called Sites and the address you’ve got to type into your browser is http://localhost/~username/etc… this annoyed me because I didn’t want to have to type the tilde character in the address and also that I had to have the files showing in a subdirectories of my user. I couldn’t be doing with it, I wanted to have addresses like ‘http://localhost/subdomain/’ and the solution of course is to use symbolic links.

Read the rest of this entry »

I’ve recently registered for accesss to the NHS’s dictionary of medicines and devices (dm+d). This was primarily to see what format the data was stored in and then to see if there was a way of utilising it in a cool webapp.

I downloaded the current release (its updated weekly) and unpacked the 5MB archive to reveal some XML and related files. Some of the files are huge (up to 32MB each and ~70MB in total) and there was no way a traditional program was going to mannage. I tried a few in fact and they all devastated my 2GB RAM and were generally unusable.

Time for a command line solution… VIM the open source text editor. Its extremely powerful and customisable but using it takes a little getting used to. VIM was able to open with only a slight delay and navigate these huge files. The next problem for me was being able to read them.

In theory it shouldn’t matter what indenting there is in an XML file as it doesn’t contain any data but I find its a lot easier to read the files if they’re ‘cleanly’ indented. I began wondering how I was going to solve the problem and thought of a few ideas… a script (PERL, PHP, shell, other…) but none of those came to fruition. After some searching I came across libxml.

You can download and compile from source if you wish but I decided to download a pre-built version from explain.com it was pretty good and another page I came across on entropy.ch explained how to use it within Vim to indent my files super quick.

Here’s what you do…

• To format type this sequence
  • :%!xmllint –format -
• Or mark the area visually and then type
  • !xmllint –format -

I’ve been doing some work involving an application that needs to query databases on separate servers however one of the servers will only accept mysql connections locally so the way round it is to forward connections from a port on one system to a port on a remote system. That way the connection to the remote database will appear as though it originated locally and be accepted.

To set up a tunneled connection you issue the following command on any client:

ssh -fNg -L 3307:127.0.0.1:3306 myuser@remotehost.com

The first command tells ssh to log in to remotehost.com as myuser, go into the background (-f) and not execute any remote command (-N), and set up port-forwarding (-L localport:localhost:remoteport ). In this case, we forward port 3307 on localhost to port 3306 on remotehost.com.