Hardware Tutorials

Changing your timezone in Debian

Chris — Tue, 15 May 2012 13:01:14 +0000

If you want to change your timezone on Debian, use the following command.

dpkg-reconfigure tzdata

Manually update Awstats on cPanel

Chris — Wed, 09 May 2012 12:03:07 +0000

Awstats is updated by cPanel once per day, but if you want to force a manual update, you can do so with the following command.

/usr/bin/perl /usr/local/cpanel/3rdparty/bin/awstats.pl -config=example.com -update

Changing your SSH port

Chris — Thu, 03 May 2012 11:59:00 +0000

If you want to change your SSH port to something a little less obvious, it’s easy to do. It’s debatable how much security it actually gives you, but it will certainly make you feel safer, and that is probably the most important thing.

pico /etc/ssh/sshd_config

I’m using pico in this example, but vim will work just as well. You should find a line which is commented out, specifying that the port is 22. This doesn’t need to be uncommented normally, as it defaults to port 22.

#Port 22

Just uncomment this and put a new port number in.

Port 8473

Now save the file and exit. Finally, restart SSH for it to take affect.

/etc/rc.d/init.d/sshd restart

Don’t forget, next time you SSH in you will need to use the new port number!

ssh -p 8473 hostname

Migrating away from register globals

Chris — Fri, 27 Apr 2012 11:51:15 +0000

If you are luckily enough to work in a Web 2.0 start up, you probably won’t have to deal with too much legacy code. But for the rest of us, we can often find ourselves working with code which can be even decades out of date.

One of the big issues in PHP has been the deprecation of register globals. Of course, this happened quite a long time ago, because the idea of register globals was just plain stupid, but recent versions of PHP (5.3 onwards), will now throw a deprecation error.

So, we need to find a way to turn register globals off.

The end solution is of course to refactor the code so it doesn’t use register globals at all. Anything short of this is going to be a security nightmare, it’s like a ticking time bomb sitting on your server. But until then, there is a way you can emulate it in your PHP code while you work to get rid of it, allowing you to turn the register global settings off.

All you need is something like this in your code.

foreach ($_REQUEST as $key => $val) {
	$$key = $val;
}

Table is full MySQL error

Chris — Sat, 21 Apr 2012 11:47:38 +0000

If you’re using MySQL’s MEMORY table storage engine for anything intensive, you may run into the following error.

Table is full

This means what it says – memory tables have a fixed size they are allowed to me, 16mb by default, and once they reach this size, MySQL will prevent you from inserting any more data, to prevent the table from using too much memory.

If you run into this error, you can either increase the size in MySQL’s configuration, or you can switch to a disk based table engine such as Archive or InnoDB.

Using locate to search for files from the terminal

Chris — Sun, 15 Apr 2012 11:44:04 +0000

Need to locate a specific file somewhere on your system? Luckily, there is an appropriated named search tool which you can use to do that. It’s called locate and it’s very similar to file search in Windows file manager.

Not all Linux installs come with locate, so you may need to install it.

yum install locate

Also, the first time you run it, it will need to build the database, so that will take a little longer. But once it is up and running, it is pretty fast. Simply use the command followed by a file name, or even just part of a file name, to get a list of all the files on your system that match.

locate httpd.conf

Mac VNC client location

Chris — Mon, 09 Apr 2012 11:39:52 +0000

There are quite a few different VNC clients available for Mac, and most of them are, in my experience, pretty disappointing. And totally unnecessary, because OS X actually comes with a build in VNC viewing client which works fine. For some reason though, Apple have kept it pretty well hidden.

Never fear though, because once you know the location, it’s easy to find and use.

/System/Library/CoreServices/Screen Sharing.app

It’s pretty simple, but then I’ve never found the need for all the extra crap a lot of the viewing clients come with – I just want to be able to control a remote computer!

Firefox updater stuck in a loop

Chris — Tue, 03 Apr 2012 11:35:35 +0000

From time to time, Firefox might try to update itself and get itself stuck an a loop where every time you try and open it, it tries to upgrade itself, fails, closes and then you have to try and open it again and the same thing happens.

95% of the time, this problem is caused by Logitech webcam software.

I don’t know why, I don’t know how, but the problem has hit my system several times and every time after some googling, the suggestion to try and close my Logitech camera software comes up and as soon as I do, Firefox is able to upgrade itself and open fine.

Persistent sudo

Chris — Tue, 27 Mar 2012 11:32:57 +0000

Sometimes, you have a number of tasks to complete as an administrator and having to put sudo in front of every command just becomes annoying. Luckily, you can change into persistent sudo mode.

sudo -i

This will then prompt you for your password and once successfully entered, you will be transfered to the root user.

It is much like doing su, except that you are prompted for your own password, rather than the root account’s password.

View disk space usage by directory in Linux

Chris — Wed, 21 Mar 2012 11:29:52 +0000

If you need to get a break down of how much space each directory is using, you can do that using the du command. Using a few choice options it will produce a list of all directories in the current folders and how big they are.

du -sch