Category: Software

Using ngrok to test on a mobile

To test a website that you're developing on your local computer on a mobile device such as a phone or tablet use ngrok.

This is the way to do it:

  1. Start up ngrok: $ ngrok http my-dev-site.local:80
    This will start up ngrok and give you a "Forwarding" URL such as
    In this case, it will direct all traffic to that URL to http://my-dev-site.local. If you run
    your website on a different port, such as http://localhost:8888, then use $ ngrok http 8080
  2. If your website's base url is configured in a config file, then update it to be the Forwarding URL.
  3. Go to the Forwarding URL (, in this example) on your mobile and test!

It's not hard to do this, but this will save me having to look it up next time!

Hide the ST3 sidebar automatically

As a mostly keyboard user, I take advantage of the keyboard shortcuts in Sublime Text. However, the sidebar is quite a lot of effort to manage, especially as I mostly leave it closed.

Firstly, you need cmd+k,cmd+b to open it. Then you type ctrl+k,ctrl+0 to focus it as opening it doesn't automatically set focus. Then you can navigate to the file you want and open it via pressing return. Finally, you type cmd+k,cmd+b to close it again.

That's a lot of keyboard combinations! Note also that you swap from cmd to ctrl too.

Revealing the current file

I find that I often want to open the side bar with the currently open file highlighted. There's a command for this: reveal_in_side_bar which you assign to a keyboard shortcut like this:

    { "keys": ["super+shift+1"], "command": "reveal_in_side_bar"},

Now, pressing cmd+shift+1 will open the sidebar with the current file highlighted. You still need to press ctrl+k,ctrl+0 to focus though.

Automating with plugins

There's a plugin called FocusFileOnSidebar that solves this problem, so if you have this workflow, then install it now.

Again, you need to set a keyboard binding:

    { "keys": ["super+shift+1"], "command": "focus_file_on_sidebar"},

It doesn't automatically close the sidebar for you though, so I created HideSidebarWhenNotFocussed that does just that.


With the combination of FocusFileOnSidebar and HideSidebarWhenNotFocussed, the sidebar works the way I want it to!

It's closed most of the time, I press shift+cmd+1 to open it with focus set on the currently highlight file. If I open another file by pressing return or go back to what I was doing by pressing Esc, then the sidebar automatically closes as it should.

Screenshot of the active window on Mac

I find myself needing to take screen captures of the currently active window in OS X reasonably frequently. The built-in way to do this on a Mac is to use shift+cmd+4, then press space and then use your mouse to highlight the window and click.

For a good proportion of the time, I'm not using a mouse, so this doesn't work great.

There's a built-in command line utility called screencapture which requires you to know the Quartz window id of the window you want to capture, so it's now a multi-step process to just take a screenshot of the currently active window.


Fortunately, there's a little open source utility called QuickGrab which solves this. (The binary quickgrab is in the repo, so you don't have to compile)

As an aside, that link is to my fork which fixes Chrome. A friend recently discovered that the current master version fails to take screenshots of Chrome if it's the active window. When I investigated, I discovered that it's because Chrome creates an invisible window at the top of its stack which needs to be ignored when looking for the active window. That's what my update does.

QuickGrab is really easy to use. From the command line you simply do:

This is a faff.

Enter Alfred

Alfred is little app that can run commands for you from a text window or via a hotkey, so this is what I use to trigger QuickGrab.

I have a keyword of screenshot set up:

Screen Shot 2016 07 20 at 13 40 58

To use, I ensure that I have the window I want to capture active and then activate Alfred, type screenshot and press return. This then creates a PNG file with a name similar to Screenshot-20160724-1124429.png on my desktop.

I also set up a hotkey for cmd+§ (finally a use for that § key!) which does the same thing.

I've created Screenshot.alfredworkflow which does all this, so simply download it and install it into your Alfred and you're good to go! This workflow includes the quickgrab binary, so you don't need to get it separately.

You can, of course, edit the workflow once you've installed it to change the keyword and the shortcut key to something else, should you want to.

Auto reloading a PDF on OS X

Currently, I create presentations using rst2pdf and so I regularly have vim open side by side with the Preview app showing the rendered PDF.

I use a Makefile to create the PDF from the rst sources, so I just use :make in vim to rebuild the PDF file and then had to switch to Preview in order for it to reload the updated PDF file. Recently a friend wondered why the PDF viewer couldn't reload automatically. This was a very good point, so I looked into it.

It turns out that while you can control Preview via AppleScript, you can't make it reload a PDF without it taking focus. I didn't want that as then I have to switch back to vim.

Enter Skim

The solution is to use Skim, an open source PDF viewer for Mac.

This app has the ability to automatically detect changes to an open file and reload it. You can open Skim from the command line using:

Note that it doesn't work straight out of the box… Open Skim and set the Preferences => Sync => Check for file changes setting. It will then look for changes to the file on disk when running.

However… it brings up an annoying dialog when it detects a file change! There's a hidden preference to disable this, so run this from the command line:

And then it works as we'd hope.

Free the Geek appearance

I was delighted to spend an hour chatting with Matt Setter on episode 14 of Free the Geek. In this podcast, we talked about Slim 3 and development in general.

Matthew gives me a great introduction (thanks!) and then we delve into the chat.

We talk about the importance of semantic versioning as I think this is key to stability in a project. It's not very glamorous to work on code where you have to maintain backwards compatibility, but it is vital to the success of a library such as Slim Framework. Developers who use your library depend on it and semantic versioning is the way to ensure that no-one is surprised. I hate it when a library I use has BC break between patch or minor version numbers that results in my software breaking, so I try not to break the contract in Slim. Of course, sometimes we've introduced a BC break by accident, but when we have, we've fixed it immediately.

We also spoke about software architecture and how important it is to make the right decisions for your project and the team building it. Projects have a lifecycle and it's useful to build appropriately for the stage that your project is at. I'm a fan of architecting for the near term with an eye to the likely long term paths and ensuring that your design fits the project.

We talk about this and more, so have a listen.

Use vim's :make to preview Markdown

As it becomes more painful to use a pointing device for long periods of time, I find myself using vim more and so I'm paying more attention to customisation so that the things I'm used to from Sublime Text are available to me.

One thing I'm used to is that when I run the build command on a Markdown file, I expect Marked for Mac to open and render the file that I'm writing. Vim has :make which by default runs make and is mapped to cmd+b on MacVim, so I just needed to reconfigure that command to do the right thing.

The easiest way to do this is via a file type plugin. These are files that live in ~/.vim/ftplugin and are named after the file type. In this case, the file is markdown.vim. The commands inside the file are then available whenever you're editing a file of that type. (You can use :set ft? to find out the file type of the current file.)

To configure what :make does, we set the makeprg setting like this:

Note that spaces need to be escaped for vim and then the space in "Marked" needs escaping for the shell, which is why there are three \s in a row.

Add this line to ~/.vim/ftplugin/markdown.vim and :make now opens Marked and life is just that little bit easier…

Obviously, if you're not on a Mac or use a different tool to preview Markdown, then configure appropriately!

Styling rst2pdf tables

I currently use rst2pdf to create presentations slide decks from reStructured Text files. I like rST a lot as it's more expressive than Markdown and allows for extension.

Tables in rST are marked up like this:

We create a PDF file with the command rst2pdf test.rst which produces a table that looks like this:

Rst table standard

To style, this we create styles within a style file and then compile using rst2pdf test.rst -s

Let's start with the table element:

Behind the scenes, rst2pdf uses ReportLab to create the PDF. The commands style maps directly to ReportLab's TableStyle commands (section 7.4 of the current documentation)

Each command contains an identifier, the start and stop cell definition to which it applies and then the style to apply. The cell definition is defined as [X,Y] where [0,0] is the top left cell, [2,3] would be the cell with e in it in the definition above. Negative numbers count from the bottom right, so [-1,-1] is the bottom-right corner.

Key options:

VALIGN Vertical text alignment. Options: TOP, BOTTOM, MIDDLE.
INNERGRID, BOX, LINEBELOW, LINEABOVE, LINEBEFORE, LINEAFTER Style of the borders. First parameter is line thickness and second is colour.
BACKGROUND, ROWBACKGROUNDS, COLBACKGROUNDS Background colour. Parameter is an array of colours, used cyclically.

The style for the table heading is called table-heading:

These settings should be obvious. I always override backColor!

The style for the table elements is table-body:

By default, it isn't styled, but if you want to change the textColor, this is where to do it.

Overriding on a per table basis

To override for a specific table, then set a class before the table:

The most common reason to do this is to set up specific column widths:

This is mostly useful when the auto-sizing routine causes odd line breaks in heading text.

If you are targeting rst2pdf, then you can also set widths using the .. widths:: directive like this:

The width numbers are percentages and it only works if you pass the command line option -e preprocess when compiling.

My defaults

My defaults currently are:

This results in the very simple table style of:

Rst default

This suits me as a starting point.

installing XHGui via Ansible

I'm still using Ansible to provision Vagrant VMs. This is how I added the XHGui profiler to my standard setup.

Theres a number steps we need to do:

  • Install Composer
  • Install the uprofiler PHP extension
  • Install XHGui
  • Set up for profiling
  • Set up host for XHGui website

Install Composer

Installing Composer requires these tasks:

Firstly we download the Composer installer and run it to create composer.phar. We then rename to composer, make executable and then create a global directory for storing the packages that we download.

Install the uprofiler PHP extension

We install uprofiler via composer:

The last two tasks copy uprofiler.ini to the relevant configuration directories. uprofiler.ini file is really simple:

Install XHGui

Similarly, we install XHGui using composer:

XHGi uses MongoDB for storage, so we install that install that first and then install XHGui via composer which pulls in all the dependencies. Note that XHGui has a extension dependency on xhprof, but we're using uprofiler, so we use the --ignore-platform-reqs flag to ignore.

XHGui requires a configuration file in it's config directory. I copied the default one and then changed it to profile every run. The minimum xhgui_config.php that you need is:

This is the place where you could put in additional checks to decide whether to profile or not, such as checking for a GET variable of "profile", for instance.

Lastly, the XHGui README recommends that you add some indexes to MongoDB. I also wanted to automatically delete old records, which is also done via a MongoDB directive. This is done via the shell script:

Note that we create an empty file that is tested in the task as we only need to run this task once.

Set up for profiling

To profile a website, we just need to include /usr/local/composer/vendor/perftools/xhgui/external/header.php. This can be done by setting the auto_prepend_file PHP ini setting. As I use Apache, I can just add:

To my VirtualHost configuration.

Set up host for XHGui website

Finally, we need a VirtualHost for the XHGui website where we can view our profiles. I decided to use a separate subdomain, "profile", so my vhost looks like this:

Where {{server_name}} is an Ansible variable that is the domain name of the site.

All done

That's it. Once I had worked out which pieces were required, putting them into Ansible tasks was remarkably obvious and now I can profile my website in development.

Shorter directory text in Bash prompt

Rather helpfully, David Goodwin left a comment about how he shortens the space taken up by the directory section of his terminal's PS1 prompt by using a Bash script to remove the middle portion.

This is a really good idea, so I ported it into my PS1 set up which resulted in some rearranging and thought I'd share here as I modified for OS X and I don't want to lose it!

The relevant portion of my .profile is:

There are three sections here. Firstly we ensure that is loaded and configure a couple of settings for it. Then we write a function called shorten_cwd() based on David's script. The main changes here are that I also look for /Users/$USER as that's where OS X stores home directories and that I don't split in the middle. Finally we define prompt_cmd() to set PS1 in a way that I understand and assign it to PROMPT_COMMAND along with tab_title.

The end result looks like this:

Shorter prompt

Setting OS X's Terminal Tab to the current directory

I use many tabs in a Terminal window quite frequently, and while the window title will show the current directory name, the tab title doesn't. You can manually change it using shift+cmd+i, but who can be bothered?

Automating it so that the tab title always matches the current directory turns out to be really easy and just requires a few lines in ~/.profile.

Firstly, we need a function that sets the tab's title to the last segment of the current working directory:

We then just need to automate calling it whenever we change directory. The easiest way to do this is to change PROMPT_COMMAND:

That's it. Whenever I change directory, or open a new terminal tab, then the tab's title now matches the last segment of the directory for that tab. Much more useful!

Terminal tabs