Matthew Daly's Blog

I'm a web developer in Norfolk. This is my blog...

24th January 2011 12:30 am

My New Mini Server

For a while now I’ve wanted a home server of some description, the idea being that it was something I could use to run a web server for development purposes, and a mail server so I could have an offline backup for my Gmail account (considering how much I rely on it, it’s only prudent to plan for what might happen if Gmail went down), and whatever else I need. Also, I only have laptops at present so I liked the idea of having something I could leave on all the time and connect to remotely via SSH.

Around Christmas, I read a forum post by someone who’d bought a PogoPlug cheap from PC World and had hacked it into a web server using Plugbox Linux, an Arch-based Linux distro. Shortly afterwards, I went into a branch of Currys in Norwich, and they had one on sale (£20 off the RRP of £70), so I shelled out for it. I already had a load of USB flash drives lying around, and an 8GB one is big enough for what I had in mind. After all, I wasn’t going to be serving anything that demanding over it, so something small and low-powered should be fine.

This weekend I finally got round to getting it set up. The PogoPlug service is actually pretty good - if you’re unfamiliar with it, it’s basically a self-hosted version of Dropbox, where you buy the device, connect it to your router, attach up to 4 flash drives or hard drives via USB, then share the files stored on them easily across your home network or over the Internet. However, this wasn’t really what I wanted.

Installing Plugbox Linux wasn’t hard - I merely had to activate SSH from the PogoPlug’s control panel, connect and kill the hbwd process, then install a new bootloader to enable it to boot the new OS. Once that was done, it was a case of attaching a flash drive, ensuring it was correctly mounted and the filesystem was set up properly, then downloading the Plugbox Linux tarball and unpacking it on the flash drive, before rebooting into the new OS.

Once it was installed, it wasn’t too hard to get the hang of pacman. I’d prefer it to have been Debian-based as that’s what I’m most familiar with, but that’s just personal preference. After a little tinkering I now have Postfix and Dovecot working on there, as well as Apache (although it might make sense to switch to something lighter, such as lighttpd or Cherokee). I’ve given it a fully qualified domain name via a free subdomain at dyndns.org, and I can now access emails on there via IMAP. Outgoing email works fine too, so I can always set up a Perl script or two to notify me if anything goes wrong by sending an email to my Gmail account. I’ve set up fetchmail to pull emails from my Gmail account via POP3, so all my email is in the process of being backed up on there, and I can use my phone to access it via IMAP, or SSH in and read it with Mutt. Going forwards, I may install Squirrelmail as well to give me more options.

One thing I’m not too sure about - I couldn’t get incoming mails to work, and I’m unsure whether this is because it’s using a subdomain (the email address is basically matthew@mydomainname.dyndns.org) or Postfix is merely misconfigured. Is it possible to receive emails to a subdomain in this fashion?

Anyway, this is a really great little machine and it’s been lots of fun getting it set up. I have to say, though, I’m really disappointed with the range of home server and NAS products currently on the market. Most of the NAS systems offer very little in the way of functionality or customisability, and most of the home servers are a bit too big, powerful and expensive, and usually run Windows Home Server, which isn’t really my cup of tea.

What I’d like to see is a small home server with a couple of hard drive bays at most, and a Debian or Ubuntu-based OS with access to apt-get and tasksel, so it’s easy to install whatever you want from the repositories. Also, give it a web interface that’s simpler than Webmin and makes it quick and easy to set up common software, but offer an advanced option for those that want it. That would be a fantastic device for end users - if it made it easy to set up a UPnP server, a Firefly server, or a BitTorrent client, that would be really useful.

13th November 2010 8:20 pm

A Slight Change...

Just to say I’ve changed the contact form I use on here. I always wanted to use one with a built-in CAPTCHA facility, as Disqus seems to have pretty much killed off the comment spam, but I was still getting it via the contact form. I’ve put off doing something about it till now, but it was getting out of hand so I’ve gone and found a new contact form. Let’s hope this kills the spam…

29th October 2010 8:49 pm

Deleting Unwanted Vim Swap Files Using Perl

Yesterday I realised that I had somehow managed to scatter Vim swap files all across the Dropbox folder I use to share Perl and Python scripts I’d written between several computers, and it would be a good idea to clear them up. I didn’t like the idea of using grep to search for them and manually deleting them, so I decided this was the ideal opportunity to write a Perl script to do it for me!

I came up with the following:

#!/usr/bin/perl -w
use strict;
use Cwd;
sub searchDir
{
# Subroutine to scan a directory looking for Vim swap files
# Get directory to read and current directory
my $readdir = shift;
my $startdir = cwd();
# Change directory to the target one
chdir($readdir) or die "Unable to open $readdir! $!\n";
print "Scanning contents of directory $startdir\n";
# Open the directory and grab the names of all the files and folders in it
opendir(DIR, ".") or die "Unable to open current directory! $!\n";
my @entries = readdir(DIR) or die "Unable to read directory! $!\n";
closedir(DIR);
# Loop through the files and folders in the directory
foreach my $entry (@entries)
{
# Skip this one and the one above it in the filesystem hierarchy
next if($entry eq ".");
next if($entry eq "..");
# If a file is a directory, call the searchDir subroutine recursively in order to scan it
if(-d $entry)
{
searchDir($entry);
next;
}
# Use a regular expression to check to see if the current file starts with a period, and ends with .swp - if it does, it's a Vim swap file
if($entry =~ m/^\..*\.swp$/)
{
# Inform the user that a Vim swap file has been found and print out the path to it
print "Found a Vim swap file!\n";
my $swppath = cwd();
print "It's the file $entry in $swppath.\n";
my $fullpath = $swppath . "/" . $entry;
print "The full path is $fullpath.\n";
# Prompt the user to delete the file
print "Do you wish to delete this file? (Y/N)\t";
chomp(my $reply = );
if($reply =~ m/y/i)
{
print "Deleting $fullpath...\n";
unlink($fullpath);
}
}
}
chdir($startdir);
}
# Get directory to begin the search
print "Enter directory to start search: ";
chomp(my $beginSearch = );
# call searchDir to start the search
searchDir($beginSearch);

Thankfully, I’ve now discovered the Preserve Code Formatting plugin for WordPress, which seems to do a good job at making the code look presentable!

This isn’t perfect - it uses recursion to examine subdirectories, and when I ran it on my /home folder it somehow wound up in /sys on my Ubuntu machine and I ended up getting a deep recursion warning (a little research suggests this happens when it goes over 100 directories in). However, it seems to work fine for scanning individual folders in my /home directory, and that’s all I really wanted anyway.

I love how Perl makes writing this kind of simple script so easy. It’s a great language for that kind of systems administration task.

27th October 2010 12:15 am

A Couple of Things I Love About Perl

In the time that I’ve been learning Perl, I’ve slowly grown to appreciate the strengths of the language more and more. There’s two things in particular that I like about Perl. Once that I really don’t think anyone is going to be surprised by is CPAN. It’s a fantastic resource - there are a huge quantity of Perl modules available for virtually any task under the sun, and they’re incredibly useful.

The other is just how good the documentation is - I’ve never considered myself to be someone who learns terribly well from Unix man pages, but perldoc seems to have very good documentation indeed, including that for CPAN modules. Also, it helps that if you don’t do well with the man page format, you have the option of running podwebserver and getting the documentation formatted as web pages.

To give an example, I’m particularly interested in all kinds of network programming, be it web development, IRC, Jabber or whatever, and I’d heard of the Net::IRC module so I decided to start using it to create a simple IRC bot (yes, I know I should really be using POE::Component::IRC instead!). Using the information gleaned from perldoc Net::IRC it was easy to get started writing a bot, and I’ve now come up with the following simple bot:

#!/usr/bin/perl -w
use strict;
use Net::IRC;
my $irc = new Net::IRC;
my $nick = "mattsbot";
my $server = "irc.freenode.net";
my $channel = "#botpark";
my $port = 6667;
my $ircname = "My wonderful bot";
my $owner = "mattbd";
sub on_connect
{
my $self = shift;
print "Joining $channel\n";
$self->join($channel);
$self->privmsg($channel,"Ready to go!");
}
sub on_disconnect
{
my $self = shift;
$self->join($channel);
$self->privmsg($channel, "Sorry about that - dropped out for a sec.");
}
sub on_join
{
# Get the connection and event objects
my ($conn, $event) = @_;
# Get the nick that just joined
my $newnick = $event->{nick};
# Greet the new nick
$conn->privmsg($channel, "Hello, $newnick! I'm a greeting bot!");
}
sub on_msg
{
# Get the connection and event objects
my ($conn, $event) = @_;
# Get nick of messaging user
my $messager = $event->{nick};
# Respond negatively
$conn->privmsg($messager, "Sorry, I'm just a bot. Please don't message me!");
}
sub on_public
{
# Get the connection and event objects
my ($conn, $event) = @_;
# Get nick of messaging user
my $messager = $event->{nick};
# Get text of message
my $text = $event->{args}[0];
# Check to see if text contains name of bot - if so message the user negatively
if($text =~ m/$nick/)
{
$conn->privmsg($channel, "Sorry, $messager,I'm just a simple bot!");
}
}
my $conn = $irc->newconn(Nick =>$nick,Server=>$server,Port=>$port,Ircname=>$ircname);
$conn->add_global_handler('376', \&on;_connect);
$conn->add_global_handler('disconnect', \&on;_disconnect);
$conn->add_global_handler('msg', \&on;_msg);
$conn->add_global_handler('join', \&on;_join);
$conn->add_global_handler('msg', \&on;_msg);
$conn->add_global_handler('public', \&on;_public);
$irc->start();

Now, this bot isn’t exactly hugely capable - all it does is greet new joiners, and tell you to leave it alone if you try to talk to it, but it was pretty easy to code it, thanks to the documentation, and it’s a good base to build on. From here, it’s easy to extend the on_public and on_msg subroutines to deal with other messages - for instance, I could use a regular expression to look for “!respond” in the text of the message and if it’s found, respond with any appropriate text.

I’ve hard-coded the appropriate details into the script in this case to make it quicker and easier to test it, but it would be trivial to change it to either accept settings passed as arguments from the command line, or have it grab these from a separate text file.

My initial doubts about Perl are really wearing off. It’s a powerful language and one that, now I’ve picked up the basic syntax, I’m having little trouble getting work done with.

19th October 2010 2:52 pm

I Passed!

Just a short post to say that today I did my CIW Perl Fundamentals exam, and passed it. Glad that’s out of the way!

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About me

I'm a web and mobile app developer based in Norfolk. My skillset includes Python, PHP and Javascript, and I have extensive experience working with CodeIgniter, Laravel, Django, Phonegap and Angular.js.