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This is a technology blog by Matthias Friedrich, a software developer and architect from Karlsruhe, Germany. more ...-
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Author Archives: Matthias
A Quick Introduction to sed(1)
The sed(1) stream editor is one of the most powerful tools from the classic Unix tool box. It is a close cousin to the ed(1) command line editor and a descendant of the ex(1) editor, the command line mode of … Continue reading
Spring Boot: Logging Failed Logins
In many applications it’s important to react to failed logins and other security-critical events, for example to log the failed login attempt to a file or to display a captcha after repeated failures. Spring-based applications come with a simple mechanism to … Continue reading
The Curse of Convenience Methods
In the old days, many Java APIs were fairly low level and pretty generic. You often had to explicitly select a concrete implementation, provide lots of parameters, and generally needed to know how things worked. This has changed in recent years – modern … Continue reading
Empty InputStream with Spring MVC
The other day, I was trying to build a simple batch upload interface for a Java web application running Spring Boot with Spring MVC on Apache Tomcat. But when I tried reading the InputStream in my controller, it was always empty. … Continue reading
Checking Whether a Process Exists
On Linux/Unix systems, there’s occasionally the need to check whether a process is running. Some people use it for simple status checks or when building their own lifecycle scripts for startup and shutdown. I don’t think it’s a particularly good practice … Continue reading
Detecting Security Upgrades on Ubuntu
In my article on unattended upgrades I described how to set up an Ubuntu system to install security upgrades automatically. This is convenient for small setups, but in an enterprise environment you typically want to perform some QA before applying the … Continue reading
Detecting HTTP/2 Support
Thanks to Ubuntu 16.04 which includes a fairly recent Nginx version, I have now enabled HTTP/2 on my private server. Of course, I also wanted to verify whether my configuration change had any effect – after all, there is no visible change … Continue reading
