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Prepopulate username field on web app login pages

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.

Next.js external Script onLoad quirk in Head

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.

Automatically monitor and restart Linux processes using monit without a process ID pid file

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.

How to enable the PHP opcache JIT compiler on Debian Bookworm

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.

How to purge residual config packages on Debian and Ubuntu

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.

Suppress PHP deprecated warnings from wp-cli

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:

Configuring an L2TP/IPsec VPN client on Ubuntu for specific IP addresses only

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.

How to prevent text from auto-selecting when focusing an HTML input element

Quite frequently I start typing text into an HTML <input type='text'> element, then Alt-Tab to a different window to look something up, then Alt-Tab back to continue typing. Firefox automatically selects all of the text when the input field is refocused, which causes me to overwrite it because I automatically start typing  with the expectation that it will continue where I left off. Here is a partial mitigation for that:

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