I am managing a Linux server where I want developers to run a Springboot application which will generate files and folders. Those newly application created files and folders must inherit the parent group ID to let other developers manipulate the generated information. chmod g+s is for setting and inheriting the setgid. setfacl -m g::rwx is […]
Posts by webmaster:

Clean Up Xcode To Free Up Some Storage Space
Free up some storage space by deleting some unused Xcode device support data. Using terminal, go to ~/Library/Developer/Xcode/iOS DeviceSupport and delete any unused device support folders. Xcode will create new sets of support data if it needs to in the future. […]

Search a word in a two dimensional array using Java
Overview I was playing this word search game with my children when I realized that I can create a simple Java application that search for words in a grid. You can checkout the source code at https://github.com/johnpili/search-a-word-in-a-two-dimensional-array-using-java Algorithm Concept Project Structure MainApp.java In this example, I created a 15×15 character array and populate it with […]
Generating Subresource Integrity (SRI)
Since launching my online recruitment platform and job vacancy portal. I became interested in rolling out my own content delivery network (CDN) to host my portal’s images, javascript and CSS. Thanks to NGINX, implementing a CDN is easy. Of course we need to ensure that our digital assets are not compromised during transport so we […]
Removing MySQL from Ubuntu or Debian Linux
One of the easiest way to upgrade MySQL installation is by first backing up the existing database and removing all traces of MySQL from the system. sudo apt remove –purge mysql* sudo apt autoremove sudo apt autoclean sudo apt remove dbconfig-mysql […]
MySQL unique index with multiple columns
In MySQL, If you have an existing table and you wanted to have unique index across multiple columns. This is very useful in implementing unique constraints. Please checkout the code snippet below. ALTER TABLE `prefix_counter` ADD UNIQUE `unique_prefix_counter`(`prefix`, `year`); […]

Using MySQL TIMESTAMPDIFF to delete unverified user records
Building a public website with user registration and email verification is typical. It will require users to validate their email by clicking a unique generated URL link. Sometimes, user registration with pending verification will grow exponentially and needs an automated cleanup of records. In this example, I created a simple MySQL stored procedure to delete […]
How to stop Mailtrack from tracking you
Mailtrack is an online service that provides email tracking capability and analytics. Using its services the sender can track when the receiver read the email, when it was viewed and where is the reader’s location. It is a great tool for marketing but I feel that this is invading privacy and I would like to […]
How to connect to a Cisco VPN in Ubuntu 18.04 LTS
Here’s the simple steps for you to connect to a Cisco VPN in Ubuntu 18.04 LTS. Cisco, an American company is the leading provider and manufacturer of enterprise network devices, telecommunication hardware, networking security and networking software. According to computer profile as of April 2018, Cisco holds a 73.9% market which makes it the undisputed […]

Bash string manipulation in program arguments
In this code snippet, I would like to run an application with a URL payload based on date and time. This code will be executed in a specific schedule everyday and I would like to dynamically inject the date and time in the program argument when the program executes. ./json2csv rules.json “ncp” “http://localhost:8080/api/zget?eid=get-ncp-mv-by-starttime-endtime&starttime=$(date –date=’yesterday’ +\%Y-\%m-\%d)+00:00:00&endtime=$(date […]