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

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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

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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

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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

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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

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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

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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

Posted in python | Tagged , , | 1 Comment