Arturo Calvo - Blog

Do you need to add more users to your AWS EC2 Linux instance? This is a step-by-step tutorial to guide you through the basic process. 1)  Open a terminal session and navigate to the path where you have  your-key-pair.pem  file 2)  Type the following command in order to extract the public key from your key pair ssh-keygen -y -f your-key-pair.pem 3) You will get as a response a string like the one below. Copy it to your clipboard. ssh-rsa AAAAB3NzaC1yVh0/ThkcfO479gFjMUVw48D2Pi4u0P+0lvP0tpzKcZ/nwnzhFIDyUHsVKMN0F97DCoPQEbk5jmyHRSBok+cuEXAMPLEt1VI7TLSAwWZj5aRedb+awFDLxBgS8SN/nvsaP4+KY8uGum10YV83/wGNZjYEVRLg9NjyDbuVERYFAKEhscyZAbWTMw2t30JELizxyXZx4s4OImfS4yOCnDLFgHFf3JUjGhTUg1O+10I3V2TB3j63166AEB+98JizrRtwJ85AUN/wmMD0V2YIiEaa2rMLbdGZw8lSlPakV3bedx+8NYf+s2+SLwB 4) Login with your ec2-user to your instance, as usual. s sh -i your-key-pair.pem ec2-user@ yourawspublicip 5) Create a Linux user account on the EC2 instance sudo adduser username 6)  OPT...

If you are using a free Heroku web  dyno, you might have already noticed that sometimes it takes too long to load your website. The reason is that single  1X or 2X web dynos go to sleep after one hour of inactivity.  This causes a few second delay for the first request. However, subsequent requests should perform normally. In order to prevent this, you can do the following: 1)  Install  Heroku Scheduler  free add-on ( heroku addons:add scheduler:standard ) 2)  From your Heroku Scheduler dashboard, add a new job with these details: - Task:  $ curl -I http://YOURAPPNAME.herokuapp.com - Dyno size:  1X - Frequency:  Every 10 minutes 3)  Save the changes That's it! Heroku Scheduler will send a "keep awake" signal to your app every 10 minutes, so that it won't fall asleep. Important: Heroku Scheduler runs one-off dynos that will count towards your dyno-hours for the month and you might be charged for extra usage.

If you want to have immediate access to your favorite sites in an app-like way, you can use Google Chrome's Create desktop shortcut  feature. It enables you to create within seconds a shortcut of a website, that will be placed on your desktop or applications menu. Just to be clear, this is not a real app , but  a desktop shortcut to Chrome's viewer, hiding the browser bars, so it does look like an app. The shortcut icon will be the website's favicon.ico image. In order to create your own desktop shortcut on any operating system supporting Google Chrome (Windows, Ubuntu,...) you can do the following: 1) Open your target website on Google Chrome 2) Click on Chrome's menu (top-right corner) 3) Go to  More tools  and Create application shortcuts 4) Tick on the kind(s) of shortcuts you want to create 5) Click on Create This is how it looks for arturocalvo.com on Ubuntu 14.04:

Let me invite you to perform the following exercise taken from Essential Scrum (Kenneth S. Rubin) . Grab a piece of paper and a pencil, draw two identical tables as shown in the figure below, and complete them with two different strategies: row-at-a-time (a, 1, i, b, 2, ii, c, 3, iii, ...) and column-at-at-time (a, b, ..., j, 1, 2, ..., 10, i, ii, ..., x). Don't forget to time yourself! The average results are 35 seconds for the row-at-a-time table, and 16 seconds for the column-at-a-time table. In addition, the first table has more chances to have errors. The first table represents multitasking , where we are continuously switching from one task (column) to another, while the second table is single tasking (we don't start with the next column until we have completed the previous one). The meaning of this experiment is that working on too many items at the same time involves a high level of over-head . Similarly, working on too few items at the same time is als...