João Rocha da Silva

• May 10, 2023

  Lenovo P1 Gen 2 - My settings for the TrackPoint and Synaptics Trackpad

  This post explains how to install the Synaptics driver on Ubuntu 23.04 and how to tune the sensitivity settings on a Lenovo P1 Gen 2.

• Nov 19, 2022

  iTerm2 (Python API): Automatically starting multiple services in separate panes

  There are awesome process monitors like PM2 to help manage multiple services, but sometimes you need to boot up multiple fully-dockerized workflows and place them in separate panes for easy log monitoring. iTerm2 has a great Python API to help automatize these repetitive tasks.

• Sep 1, 2022

  Installing clamav (open-source antivirus) for Mac using macports

  Using a vintage Mac requires hardening, such as enabling the Firewall’s Stealth Mode, disabling File Sharing options in the System settings, and installing an anti-virus and being overall mindful of which parts of the web you visit. Here is how to install clamav, a free and open-source alternative for older Apple hardware still stuck on older OS’s. We will be using MacPorts for this short tutorial.

• Jul 30, 2022

  Homebrew: A list of useful casks for NodeJS developers

  All the casks I usually like to install on a new developer machine.

• Jul 30, 2022

  Homebrew: Fix Command Line Tools installation on macOS Ventura Beta

  1. Install XCode Beta 14.0 from Apple’s Developer website.
  2. Open XCode, set path to command line tools using XCode GUI
• Jun 30, 2022

  iCloud always full? Organise your AirDrop photos and old hard drives in minutes

  IN CONSTRUCTION!

• Jun 26, 2022

  OWC Thunderbay 4 Mini review: 20TB, RAID, Thunderbolt 3 for less than €800

  
  The Thunderbay 4 Mini Packaging

• May 20, 2022

  Automatic synchronization using fswatch and rsync

  Here is a simple script to automatically synchronize a local directory with a remote one whenever a local change is detected. Combined with a compiler that watches for changes running on the remote server, it can be used to offload heavy compilation tasks to a remote server while using a less powerful computer to edit sources.

• Apr 13, 2022

  Getting Python to install and run on M1 Pro MacBook Pro with macOS Monterey

  In order to get Bash Beautify working on my Mac, I had to have both the python2 and python3 commands running on my Mac.

• Mar 10, 2022

  Review of my Mac computers, from 2007 to present

  Here is a little bit of my personal history using Macintosh computers, from a pet project Hackintosh circa 2008 to the current MacBook Pros powered by Apple Silicon.

• Mar 7, 2022

  Using a vintage Mac with 10.6 Snow Leopard in 2022

  Here is a guide on how to use AFP (Apple Filing Protocol) shares to offload heavy compilation operations to a more modern and powerful machine, while using a vintage Mac for simple text editing and viewing the compiled result in the web browser. This may be of use to those of you running older PowerPC Macs, such as the 12-inch Powerbook G4, one of the most beautiful computers ever created. As long as its Mac OS X version supports AFP, you should be good to go.

• Aug 23, 2021

  Generating diagrams from XSD files on Windows

  I always loved the Oxygen XML Editor, in particular the way it represents XML Schemas (or XSD’s) in an easy to understand, visual way. However, the price tag is very high, especially when you have to pay for it on a yearly basis.

• Aug 19, 2021

  Git rebase, rolling back commits, and a Sourcetree caveat

  Until recently, I used mostly merge operations in git. However, recently I have been using rebase more often.

• Aug 5, 2021

  How to make nice diagrams from your databases (SQLite, PostgreSQL)

  There often comes the time when you have an existing database and you need to build a nice diagram to analyse it quickly. Here is how to do it using open-source software. We are going to be working on a Mac running macOS 10.14 Mojave, as well as an SQLite database.

• Aug 2, 2021

  Java versions on macOS without pain, complete guide

  An ages-long problem that once in a while comes to take a couple of hours away from a developer: How to properly manage multiple versions of Java in a single Mac, and how to switch between them painlessly.

• Jul 15, 2021

  3287% performance boost with 1 line of code? The impact of indexes in PostgreSQL performance!

  Slow queries are usually easy to identify, since they take at least seconds or minutes to run. Here I show a different type of optimization procedure for queries that are not expensive when ran once or twice, but that can really take a toll on a system if ran many times. We need to determine the total cost of these small queries so that we can optimize them.

• Jun 4, 2021

  My standing desk project: purchase guide, assembly and review

  New standing desk

• Mar 14, 2021

  How to repair MacBook Magsafe and Magsafe 2 chargers

  

• Mar 4, 2021

  Convert Standalone MongoDB to Replica Set with WiredTiger storage engine (macOS and Homebrew)

  If you want to take advantage of MongoDB Change Streams (which will allow an event to be fired whenever a collection is modified instead of polling the database for changes), you need to change your MongoDB instance to a Replica Set. Here is the full process using the Terminal.

• Feb 16, 2021

  Splitting videos automatically by length using ffmpeg and the Terminal

  Google imposes a limit of 10 GB per video on uploads to Google photos. I had some very large videos that I filmed on my iPhone and that Google Photos was refusing to backup. A possible solution is to:

• Dec 20, 2020

  Fixing no Spotlight results on macOS Big Sur

  After upgrading to macOS Big Sur I noticed that Spotlight would no longer list any local applications or files.

• Dec 19, 2020

  Finding illegal characters in a directory

  Sometimes you need to grep for occurrences of invalid files in an entire directory. I personally came across this issue when running htmlproofer to validate this blog’s generated files. Let’s take a look at the error message and then the solution.

• Oct 15, 2020

  Restoring a dmg file to USB using only the Terminal

  If you need to restore an image of an old version of Mac OS X (Leopard or Snow Leopard, for example), using a newer version of macOS (Mojave or Catalina) you may encounter messages like this, due to the uselessness of the newer versions of Disk Utility.

• Jul 22, 2020

  SSH and SCP broken: Fixing `dyld: Library not loaded`

  Nagging error that happens again and again when I try to use ssh or scp in macOS (since Catalina):

• Jul 22, 2020

  Make your PDFs searchable using OCR for free on macOS

  Ever encountered a PDF from a scanned document where Ctrl+F does not work? No text selection too?

• Jul 13, 2020

  Improvising a fan from a PC power supply and a computer fan

  These days have been blistering hot, so I had to improvise a fan with some hardware I had at home. Here I am using a Corsair AX860 Power Supply and a 120mm Corsair ML120 fan that I had lying around.

• Jun 13, 2020

  Replacing intel_pstate power management with acpi-cpufreq in Ubuntu

  After upgrading my T420 with a 1440p panel, I noticed some lag in the user interface. On top of that, once the CPU heats up above a certain level, it will be slow until you restart the computer for some reason. This seems to be around 80ºC, which is very normal if you upgrade your Lenovo T420 to a crazy-hot Quad-Core i7 Extreme CPU like I did.

• May 12, 2020

  Solving no keyboard shortcuts after upgrade to Ubuntu 20.04

  After upgrading to Ubuntu 20.04 I saw that my keyboard shortcuts no longer worked (Ctrl + T, Shift Insert, Ctrl + V…). The Super key also was not working.

• May 6, 2020

  Creating Tag page in Jekyll that considers both pages and posts (GitHub pages compatible!)

  A pages+posts “tags” page for your Jekyll blog

• Apr 18, 2020

  Using find and xargs to deep find files in a directory tree and copy them

  I was looking for an easy way to install a lot of fonts in Ubuntu. By the way, I discovered a great GitHub repository with many interesting ones here!

• Apr 17, 2020

  Disabling a specific Bluetooth adapter in Ubuntu 19.10 (Hacked Lenovo T420)

  This all started because my Bluetooth mouse was lagging and the pointer skipping!

• Feb 2, 2020

  Semi-automated correction of SQL exercises in Moodle

  At FEUP we have a Moodle instance provided by the University of Porto. I think Moodle is an awesome tool for e-learning: I use it as much as possible for centralizing lecture contents, organize assignment deliveries and provide not only grades but also individual feedback to my students.

• Jan 3, 2020

  Static analysis of PHP code using open-source code quality tools

  While it does not replace good judgement and programming practice completely, it can be interesting to perform regular code quality analyses to make sure that your teams (and students) are writing good PHP code. This is a small guide on how to install them in macOS and how to use them to automatically produce metrics for all code repositories in a folder.

• Dec 3, 2019

  Download music from YouTube for free using macOS

  Often you want to download videos from YouTube or extract audio from them.

• Nov 25, 2019

  Fixing permissions of the public_html folder

  Sometimes you may not be able to run PHP files or view HTML in a web server. This can be related to permissions and/or the lack of a .htaccess file in your public_html folder.

• Nov 21, 2019

  Disable and enable user accounts in Linux

  Sometimes you need to disable user accounts (say, people enter and leave the team).

• Sep 10, 2019

  Fixing `unable to determine url for /Volumes/TimeCapsule in Apple Time Machine`

  So far, macOS Catalina Beta has been a mixed bag of experiences. After critical crashes to the login screen on Beta 3, Beta 7 seems to be stable enough for daily use.

• May 17, 2019

  Tuning the sensitivity of the Lenovo TrackPoint on Ubuntu

  I have recently installed Ubuntu Budgie on my Lenovo ThinkPad T420. So far, the experience has been great. However, a crucial part of the IBM/Lenovo experience is the TrackPoint, the red nub at the center of the keyboard. Love it or hate it, for many people it is the main reason to buy a ThinkPad. Here is how I configure it to run on Ubuntu.

• Apr 20, 2019

  How to monitor connection leaks

  Database connections need to be managed properly. If we keep opening connections to a database without closing or releasing them (in the case of a connection pool), the database will soon stop responding.

• Apr 2, 2019

  Fixing broken R packages in Ubuntu 16.04

  I had an issue with install R on Ubuntu 16.04. Message was about some inability to install a dependency of the main R package.

• Apr 2, 2019

  RDA Research Data Alliance Plenary 13 at Philadelphia, Day 1

  Under the motto “With Data comes Responsibility”, the RDA 13th plenary at the beautiful city of Philadelphia.

• Mar 25, 2019

  How to set up a basic venv for python development

  Before writing your code, you should make sure that your python environment is easily portable to other machines. None of that “Works on my machine” nonsense!

• Feb 16, 2019

  How to set up Automatic Updates on Ubuntu Server with scheduled reboot time

  If you administer servers, you know the importance of keeping your packages up to date for security concerns.

• Feb 10, 2019

  The story of my highly upgraded Lenovo T420

  I have a Lenovo T420 that I love because of its unmatched 8-row keyboard. It is old and was slow with its original i5-2520m cpu… but it is very Linux friendly and runs MacOS too. A GitHub user called tluck has compiled everything you need to get it running under MacOS (yes, even Catalina, an OS that no mac from 2011 supports…).

• Jan 13, 2019

  My spicy cuttlefish recipe

  Here is a great recipe for cuttlefish, for those that like spicy food. With strong Portuguese roots, I added some oriental touches to give it an Asian twist, but without overdoing it.

• Jan 9, 2019

  Squid proxy cache in an ancient, hacked up Mac Mini 1.1

  A proxy cache server acts as an intermediary between your machine and the internet. Say, for example, you have two machines in your network, and a third machine that you want to dedicate to caching web content. Here is how to set it up on a Mac.

• Dec 31, 2018

  How to set up MAMP to enable .htaccess and mod_rewrite debugging

  Here is how to enable htaccess overrides in a MAMP server for local development. This is useful to test PHP configurations where you want to use a .htaccess file to redirect all requests to a specific file, say, an index.php that acts as a router, enabling you to use pretty URIs such as /users, /users/new, etc. for your PHP application.

• Dec 14, 2018

  What is the difference between REST and AJAX?

  A question from one of my students at the Languages and Web Technologies class at FEUP.

• Dec 10, 2018

  How to search for good references for a State of the Art

  How to search for good references

• Dec 6, 2018

  Logging out a session properly in PHP

  Logging out a user in PHP, the right way.

• Nov 5, 2018

  Install Docker on Ubuntu 18

  Installation Script

• Nov 5, 2018

  No space left on device - Full /boot partition

  Do you have messages like this?

• Oct 28, 2018

  Why LaTeX is better for scientific writing

  Here is my short list of reasons why LaTeX is so much better than Microsoft Word for scientific writing.

• Oct 28, 2018

  Installing Semantic Mediawiki, a complete and revised guide

  How to install Semantic MediaWiki on Ubuntu 18.04 LTS

• Jul 12, 2018

  Fixing locales error in Ubuntu

  Tired of warning about locales in Ubuntu? Me too, and there is a fix.

• Jul 10, 2018

  Fixing Virtualbox and Vagrant in macOS Mojave 10.14 Public Beta 3

  The new beta of Mac OS X Mojave is mostly stable and so far it has been a good experience… Apart from the recent issues that i have faced with homebrew legacy libraries and this recent problem with Virtualbox, which loads a Kernel Extension that has not yet been approved by Apple.

• Jul 9, 2018

  How to run a command in a Docker container (or how to SSH into a Docker container)

  Docker containers can be a great way to try out some scripts before they are ready for production. One of the basic tasks is to run a command in a specific container. Here is how to do it.

• Jul 9, 2018

  How to backup MySQL, OpenLink Virtuoso and ElasticSearch database data via command line in Linux

  MySQL, ElasticSearch and OpenLink Virtuoso are all dependencies of our research data management platform, Dendro. Here is how we back up the databases.

• Jul 9, 2018

  How to check the size of a directory in linux

  How to check the size of a directory in linux, in human-readable form.

• Jul 5, 2018

  Fixing missing headers for homebrew in Mac OS X Mojave

  If, like me, you tried installing imagemagick or other software using Homebrew, you might have ran into this error:

  1
  <libxml/parser.h> no such file or directory
  

• Jul 4, 2018

  I just changed the battery on my Mid-2014 Macbook Pro Retina 13''

  I just changed my 13’’ MacBook Pro Mid-2014’s battery. Its not easy, but not as hard as I initially thought. The trick is to remove the adhesive with some dental floss or fishing line. Fishing line is actually better because it is made up of a single nylon filament and will be more robust than the dental floss, which tends to break more easily.

• Jul 2, 2018

  How to add your SSH keys to a server for password-less logins

  SSH keys allow you to login into your SSH server without having to remember passwords and with much stronger security. It’s like having a super long password that you never have to remember… Just keep your private keys in a safe place.

• Jul 2, 2018

  How to install Jekyll using Homebrew, Mac OS X 10.14 Mojave Beta

  This short guide shows you how to install and run a Jekyll blog in your Mac. Mojave broke some things for me in Homebrew, so this addresses some possible issues that you may also face.

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