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Munin is a useful tool for generating graphs of system performance. When setting it up on Debian and Ubuntu, it doesn’t automatically enable monitoring of Apache or MariaDB, but the reason why isn’t easy to spot.
Often I need to access several web apps running on the same hostname, with different usernames. For example, I might need to access webmail, phpMyAdmin, and a wiki all on https://dev.example.com/. For convenience, I usually save the login details in the web browser, but if there are multiple different usernames on the same host then the browser doesn’t know which one to automatically populate into the login field. However, if each login page itself prepopulates the username, then the browser is then able to prepopulate the saved password as well.
If you’re using the native desktop Spotify client on Debian or Ubuntu, you may have noticed that they don’t seem to have figured out how to rotate their apt signing keys automatically. This means that apt updates will periodically fail with the following message:
Recently I was cleaning up some data as part of a data analysis project, and ran into a frustrating problem with stray backslashes in text fields. Here’s how I ended up solving it.
Overview of the problem
Sometimes it’s necessary to load external JavaScript into a React/Next.js system. There are various ways of doing this, but one of the most commonly recommended is via Next.js’s <Script /> component. Today I discovered a strange quirk. If you load the script inside a Next.js <Head /> component, then the onLoad function must be a conventional JavaScript onload function, not a React function. If you try to use a React function, it will not run, but there will be no warnings.
On some of the servers that I maintain, I use monit to monitor the status of key system services. I have it set up to try and automatically restart the service and only notify me if it’s unable to restart it. This helps to keep everything running smoothly without manual intervention.
PHP 8.0 introduced a new JIT compiler, which theoretically decreases the processing time for PHP-generated content. According to the official instructions, it’s very easy to enable, but it is disabled by default in Debian and requires some slightly different configuration changes to re-enable. Be aware that the Debian maintainer decided to disable it due to reports of segfaults from some users.
The apt package management system often ends up uninstalling packages but leaving behind their configuration files. For many years it’s been easy to find them using the command dpkg -l | grep --perl-regexp '^rc', but it required fiddling around with shell commands to purge the packages (remove the leftover configuration files) because apt didn't support a way of filtering them by installation state. Since apt version 2.0 this is no longer the case, but I always forget the command and searching online usually turns up the old and overly complicated way of doing it.
This is a follow up to my previous article on automatically updating WordPress using wp-cli. A number of the sites that I maintain run on servers that have been upgraded to PHP 8.x, but some of their plugins and themes include deprecated code. As a result, every time that cron runs to check for updates, I get a load of PHP Deprecated warnings. Searching online suggested a few fixes, but none of them worked for me, so I developed a different workaround.
Things that didn’t work:
Every few months I have to set this up on a new machine, and it’s always very confusing because most VPN instructions are for Windows, Mac or mobile devices. Ubuntu’s GUI tool for managing VPNs is quite powerful, but not very intuitive. Here’s how to find all of the necessary options.