Tuesday, June 9, 2015

Simple date math in bash script

To catch up with my blog, I needed to extract data from a twitter feed. Usually I update the blog on a weekly basis. Since I didn’t find the time recently, I fell behind.
I was looking for a quick solution to download all the feed data at once. A bash script should be good enough.
The script that I use to extract the data from the twitter feed, expects a date argument in the form mm/dd/yyyy. The script will extract all data for the range [date - 7days, date]

Create the series of dates

I need to create a series of dates for several weeks. Given a start date, I’m going to produce new dates with a 7 day interval. The starting date is included in the series. Here is what I ended up with:
#!/usr/bin/env bash

set -e

# startdate in the form mm/dd/yyyy

for ((i=0;i<${weeks};i++)); do
    newDate=`date -j -v+${offsetDays}d -f "%m/%d/%Y" ${startDate} "+%m/%d/%Y"`

    startDateFilename=`echo ${newDate} | sed "s/\//-/g"`

    echo ${startDateFilename}
    # download the twitter data and redirect all output to that file
    exec &> weeklyTwitterData-${startDateFilename}.txt
    # call the script to extract the data from twitter stream
    coffee src/WeeklyStats.coffee -n ${startDate}

Since I didn’t want to do all the calendar math myself, I rely on the magic of the date utility. The line defining newDate is where the magic happens. Parsing a date ${startDate} in a given format %m/%d/%Y, adding $offsetDays to the parsed date and print out the new date in the format %m/%d/%Y.
That’s it.

Wednesday, May 13, 2015

Setup iTerm2, zsh, oh-my-zsh and powerline fonts on OSX

After waiting for a long time, I finally updated my Mac to OSX 10.10. Right after the installation, the usual tweaking process begins to make you feel at home. These are my notes to make the shell look good.
I wanted z-shell, oh-my-zsh and these modified powerline fonts to make the command prompt look cool.
If you want to follow these steps, it's recommended to have homebrew installed to install zsh-shell.

Ready, set, go!

Open your terminal and prepare to type.


The easiest way it to install iTerm2 with homebrew. Run this command:
brew install iTerm2


Run this command curl -L https://raw.github.com/robbyrussell/oh-my-zsh/master/tools/install.sh | sh


Powerline is a project that provides tools to customize the status line and command prompt of several applications. To achieve this, they use special glyphs that are available through patched fonts. These are the powerline fonts. Download the font from here and install it by double clicking. This will open the Font Book application and install the font for you.


Now it's time to put everything together.
  1. Open iTerm2
  2. Go to Preferences -> Profiles -> Default -> General and type /bin/zsh into the text field next to Command (this will use zsh instead of your default shell)
  3. Go to Preferences -> Profiles -> Default -> Text and change the Regular Font and the Non-ASCII Font to 11pt Inconsolata-dz for Powerline
  4. open ~/.zshrc with your favorite text editor and change ZSH_THEME to agnoster
That's it. Make sure to start/restart iTerm to see all the changes.


oh-my-zsh Powerline change osx shell

Wednesday, May 6, 2015

Electron mystery on OSX solved

Do I look like an idiot? I don't know. But I felt like one for the last 2 days.

2 days ago I started to look into on a great project idea, to replace the Brackets Shell with Electron. Great idea! I wanted to contribute and fix issues that crossed my way. But, I followed the given instruction to clone the repo and setup all dependencies. After everything was download and in the right place, I ran npm start to bring up Brackets in it's new electron shell. But that first attempt failed with this error:
> Brackets@1.3.0-0 start ~/develop/fun/OSS/brackets-electron
> electron .

r CONFIG_PATH = path.resolve(utils.convertWindowsPathToUnixPath(app.getPath("u
TypeError: app.getPath is not a function
    at Object.<anonymous> (~/develop/fun/OSS/brackets-electron/app/shell-config.js:13:71)
    at Module._compile (module.js:418:26)
    at Object.Module._extensions..js (module.js:436:10)

I was wondering, if there was something important missing in the setup instruction, I simply made a mistake or my system config was tricking me. After checking with the guys who started that effort, I was left with this weird error.

I started to research and looked for others having the same issue, but I couldn't find anything. Okay, it has to be my machine setup. Back at home, I started to setup everything on another machine to see if it works there. The result was the same! The error showed up on a different Macs, with a different OSX versions.

I went back to our slack channel and carefully mentioned, that I'm still not able to get it running yet. Someone replied, that I can install Electron globally and try it again. But this turned out to be a red herring. Nothing has changed and it was really frustrating, since nobody else seemed to have these issues on OSX. I promised them to help, but I could even review and test pull requests.

I did some more research and came across this great blogpost from Thorstenhans. He provided a boilerplate project for an app that uses Electron. I was so happy. I followed his instructions to create a clean app. Everything went fine and I was excited because it's using es6. Unfortunately, the result with Electron was the same.

I left a comment for the blogpost asking, if he has encountered this issue before. Nothing worked for me as expected. So, it must be my machine I concluded. But two machines at the same time?

I mentioned my inability to launch Electron on OSX, briefly in the slack channel for electron-brackets. I felt like an idiot at this point. Somebody who distracts everybody with some nonsense. Nobody had an idea what might help to resolve this misery to help me getting started.

Since the electron-brackets version on Linux seemed to work fine, I decided to pull my Linux VM out of the drawer and give it a try. I cloned the repo, installed everything and typed npm start at the console. Guess what? It worked! I was happy. That is awesome and I'm finally able to help.

But I wasn't happy that my day-to-day machine didn't play well with me. I had a conversation with Thorsten Hans (look at the comments here). He solved another mystery for himself along the way, but I didn't make any progress.

Long story short, I started to get rid of my nodejs installation, install nvm from scratch and hoped to resolve the issue. No luck. But then I inspected the environment variables for anything nodejs related and I found NODE_PATH. It seemed somehow messed up. This post recommended to undef NODE_PATH to solve another issue. But it helped me too. npm start is finally working and the biggest mystery, that let me look like an idiot was resolved.


To Thorstenhans for the back and forth to help me resolve the issue. Thanks to Andrew MacKenzie to mention often enough, that the Linux version is doing a good job for him.