Category Archives: tech

14 Jan
2011

Navigating Bash History with Ctrl+R

I spend a lot of time at command line, and bash records the history of all the commands I’ve typed and puts it in .bash_history (there’s a limit on how many it stores but for me it goes back a few days). I find it really useful to look back at the history to use the same commands again or edit them slightly. You can press the up arrow to go through your history but it can take a really long time to find what you’re looking for. So instead, try Ctrl + r.

To do this: first press Ctrl + r, then start typing the command or any part of the command that you are looking for. You’ll see an autocomplete of a past command at your prompt. If you keep typing, you’ll get more specific options appear. You can also press Ctrl + r again as many times as you want to, this goes back in your history to the previous matching command each time.

Once you see a command you like, you can either run it by pressing return, or start editing it by pressing arrows or other movement keys. I find this a really useful trick for going back to a command I know I used recently, but which I can’t remember or don’t want to look up again. I hope this is a useful trick for you too!

10 Jan
2011

Github API: Issues List

I’m deeply involved with an open source development project (joind.in, the event feedback site) and we recently made the decision to move our issue tracking away from GitHub (because it’s awful and meets none of the requirements for a bug tracker, but that’s a post for another day). In order to make this happen more smoothly, we wanted to migrate our open issues from github (to JIRA Studio, since Atlassian generously provides accounts here for worthy open source projects – thanks Atlassian!).

I looked around for some export functionality for github but I got a lot of posts complaining it wasn’t there. Since I hate applications that take your data and refuse to let you remove it, I was disappointed by this news but further inspection showed that although there might be no “export from github” button, there’s an API that more than has it covered. The API returns JSON which is easy to work with from many programming languages, and is perhaps even more powerful and flexible than the simple export I initially expected, so here are some examples.

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06 Jan
2011

Adding Multiple Axis Labels to a Google Chart

Recently I’ve been working on a project using Google Charts API and I absolutely love it. It makes pretty graphs and shows data really nicely – and it’s very painless. I did trip over a little trick today though which took me a little while to work out, so I thought I’d share it here: how to add two levels of label to an axis.

The axes in Google Charts are a bit interesting, because what they display bears absolutely no resemblance to what data is there – you label the axes separately, even if they are numbers. To label multiple things – in this example a scale and some units, you simply specify the axis more than once. To specify which axes should be shown, use chxt (CHart aXis Title) and set something like this:
&chxt=x,y,y

Then add the labels as required, for example:

http://chart.apis.google.com/chart?chxl=1:|Sun|Mon|Tue|Wed|Thu|Fri|Sat|2:||Week+37
&chxr=0,0,20&chxs=0,676767,11.5,0,lt,676767&chxt=y,x,x&chbh=a
&chs=360x240&cht=bvg&chco=CC0057CC,3D7930&chds=0,20
&chd=t1:10.059,12.578,13.6,11.135,11.018,7.104,6.92|50,60,100,40,20,40,30

This produces a graph like this:

You can then add labels (using chxl) and ranges (uses chxr) to your axes as you wish – and even add axis labels to the top and right hand graph edges, using the t and r axes, with as many of each as you’d like, and using their list position as a parameter to the range/label settings. I hope this is useful to someone, as it took me a little bit of research to figure it out.

27 Dec
2010

Launching Links in Opera from Command Line

I’m an Opera user but I use a number of applications from the command line, and often I want to launch links from those applications into my web browser. I’ve just switched over to reading my feeds using canto (web applications are becoming decreasingly accessible these days, although I’m saving that rant for another day) which is a console-based application. This, like many other applications, allows you to specify a URL handler to use when you want to visit links.

To launch a link into a new tab in an existing Opera window, I simply used this:
opera --remote 'openURL(<url>, new-page)'

Where the <url> is the address to access; the same trick works in other programs too. For example I use irssi for IRC, with the openURL plugin, and this can do the same trick. To launch the link I simply set the http handler like this:
/set openurl_app_http opera --remote 'openURL($1, new-page)'

Since I have to look these settings up every time I want them, I thought I’d blog them for next time – and of course for anyone else who finds this useful between now and then!

22 Dec
2010

Speaking at DIBI

In June 2011 I’ll be speaking at a rather awesome event called DIBI at the Sage in Gateshead (if you’re a southerner, then Gateshead is near Newcastle, which is “up north”). DIBI stands for “Design It, Build It” and has two tracks, one focussing on development and one focussing on design. Last year was their first event and although I didn’t attend, I have only heard good things about both the conference and the socials!

I love it when really fantastic events happen in the north, especially because I’m based in Leeds and have ties to the North East, so I’m very excited to be speaking. Tickets go on sale in the New Year and I hope I’ll see lots of you at the Sage on 8th June!

17 Dec
2010

OAuth Google API for Unregistered Applications

It is pretty common when using OAuth for there to be a relationship between the provider and consumer; as a consumer you usually register with the provider to obtain a consumer key and consumer secret. Google’s APIs however do not require this. It is recommended that you register your application, however it is also possible to use OAuth without registering.

To make this work, when you sign your OAuth request Google will accept some default values for consumer key and secret – see their documentation on signing oauth requests. To do this, set both consumer key and secret to the value “anonymous”, and proceed as you normally would. The only difference so far as I can see is that the user will be shown a more cautious message when they are prompted to grant access to your application. Personally I think this is a great approach, particularly when prototyping ideas. Registering the applications though is simple and quick so I’d recommend registering for most applications once they get beyond concept stage.

06 Dec
2010

Skills Analysis for Teams

When I spoke at PHPNW10 in October, I talked about teams, skills and the importance of benchmarking things in order to illustrate improvements. If you didn’t see the talk, the video and slides are linked off the conference site. In particular I talked about the importance of analysing skills in a team, then improving them, then analysing again to see how things had changed. This post is about that process, some techniques that might apply, and what to do with the results when you get them.

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15 Nov
2010

256 Colours in Vim

Recently I’ve been looking at different vim colorschemes, after using vimdiff and finding I couldn’t see half of the code. I’ve been using relaxedgreen for ages, and it is excellent but I find the blue really hard to see on my black background so I was in the market for an alternative.

Touring Colours in Vim

Please excuse the all-over-the-place spelling in this post, I’m British so “colour” is a word and “color” is a vim command. Confused? Me too

I grabbed two fantastic scripts – the Vim Color Sampler Pack and the rather awesome ScrollColors plugin which allows you to cycle through all your colorschemes and try them out.

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12 Nov
2010

Curl and Cookies

I noticed the other day that the cheat sheet I have on this site for curl doesn’t show how to use cookies, so I thought I’d remedy that omission, and quickly! Being able to use the command line to authenticate and then go on and use part of a site behind a login box can be really handy, and it is also super-simple.

-c to Save a Cookie

Pass the -c switch followed by a filename and curl will write the cookies to a file. This is the “cookie jar” and you can dip into it whenever you want to send the cookies back with a future request. For example:
curl -c cookies.txt http://www.lornajane.net
This writes a file named cookies.txt to the local directory. When I look in it, it contains:

# Netscape HTTP Cookie File
# http://curl.haxx.se/rfc/cookie_spec.html
# This file was generated by libcurl! Edit at your own risk.

www.lornajane.net FALSE / FALSE 0 s9y_4e071c5ccc553288993faf0369cb076c 539e01676501366ea0f04e2646b1a31d

-b to Send Cookies

All I do when I want to use the cookie on future requests is pass exactly the same command but with a -b switch; this will read the named file and send the cookies along. You can edit the cookies as you wish, at your own risk of course, and this makes the use of cookies and curl an absolutely invaluable technique for testing! It’s also common to use it on sites where you want to download a file directly to the server but the site requires login first.

20 Oct
2010

Is Enum Evil?

When I work on database designs, either on my own projects or as advisor to others, I often find people very reluctant to use an enum type for any columns. Now, I’m not about to advocate the gratuitous use of an enum column, they definitely have some pitfalls, but I think it is important to understand these rather than just shouting “enum evil!” if anyone should mention them.

There are cases where an enum is the correct choice for a particular type of data, so let’s look at what an enum type actually is and does.

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