Thomas Yuan

ConcurrentHashMap is designed to support concurrent access from multiple threads without the need for external synchronization. It achieves this by using var...

Certbot on Oracle Cloud VM

2 minute read

Try to get a certificate from Let’s encrypt on Oracle’s compute instance (vm) with command certbot certonly --standalone but keeps getting error: Certbot fai...

AWK 101

less than 1 minute read

Note for Learning Awk Is Essential For Linux Users download awk is a tool to process text, line by line. Variable $0 means whole line, $1 means the fi...

Java Features By Version

1 minute read

Java 8 https://www.oracle.com/java/technologies/javase/8-whats-new.html Functional Interfaces and Lambda Expressions Default and static metho...