Charlie Harvey


111 Geekery articles in total, showing 31 to 40

  • Let’s make morse code with Haskell

    Let’s make morse code with Haskell cover image

    Recently, nor and I went with her family to Bletchley Park. Nor’s grandmother used to be a radio operator at what we think was one of the Y stations, near Leighton Buzzard. She spent her time transmitting and receiving coded messages in morse code — in 5 character blocks of apparently

  • Using modsecurity with RBLs to mitigate comment spam

    Recent weeks have brought a pile of new comment spam on this site. I’ve explored a few ways of mitigating the amount of crap I receive, and hpoefully wasting some spammer bandwidth. This includes various lookups that are built into the code that runs the site, dodgy posts get timed out for a

  • Using from Bash

    I recently learned of a new web publishing tool called, which lets you publish stories to a custom url by sending email to a particular email address. Quite a nifty idea.The service is a model of minimalist, yet highly functional design. The simplest thing that could possibly work, you

  • PiPhone: A smartphone made of a Raspberry Pi

    A seriously cool idea this; making a smartphone out of a Raspberry Pi. A guy called Dave Hunt put together the PiPhone, using a 2.8 inch adafruit TFT touchscreen and a Sim900 GSM/GPRS module. The result is pretty sweet as you can see from the video.Dave did a PiPhone writeup on his sit

  • Quick tip: Postfix operators in GHCi

    The other day I wanted to work out what 52 factorial was. I’d beeen to a pub quiz the night before. What can I say? It is pretty easy to make the factorial function in Haskell. Something ike this usually suffices. fac :: Integer -> Integerfac n = product [1..n] I wanted to be

  • Tip: Change or add passphrase on existing SSH keys

    Today I needed to add a passphrase to an ssh key. The key had previously been used for automated batch processing work in cronjobs, and thus didn't have a passphrase set — a bit of a security no-no. A quick scan of the ssh-keygen manpage led me to the -p flag, which updates or creates a pas

  • Quick tip: Using vimdiff with git

    Vimdiff is an amazing tool to work with file differences and it particuarly suitable for use when examining differences between git revisions. There is a command built in to git that is called git-difftool. It allows you to use an external tool to look at your diffs this tip just shows how I like

  • semalt: Marketing by analytic vanity

    I’ll let you in to a secret. I sometimes look at the analytics on this site. I anonymize the last octet of the address of course, using the piwik plugin. One of the things I look at is the referrers that are sending me traffic. In December and January I was seeing an improbably amount of traf

  • Quick tip: Find all image sizes ImageMagick and find

    A super quick tip this. The other day I needded to find images bigger than a given width on the New Internationalist website. The quickest way I could think of to do this was to use find to locate all the files and combine that with ImageMagick’s identify command. And finally to pipe that t