The Silent CPU Spike
In Ubuntu, the `man` command is the standard way to access manual pages for installed software. To ensure these manuals are indexed and searchable (e.g., using the `apropos` command), Ubuntu utilizes a background database managed by the `mandb` utility. When you install new packages or run large system updates using `apt`, a trigger is often fired that automatically runs `mandb` in the background to update the manual page index. While this keeps the documentation current, the `mandb` process is notoriously I/O and CPU intensive. On older hardware or low-resource Virtual Private Servers (VPS), this automatic generation can cause a noticeable, temporary performance spike immediately following an update.
Disabling the mandb Trigger
To prevent these post-update performance hits and stop Ubuntu from automatically generating man page indexes after package installations, you can disable the `mandb` apt trigger.
This requires administrative privileges in the terminal. Open your terminal (Ctrl+Alt+T). The easiest way to bypass the trigger without breaking the package manager is to override the trigger configuration. Type the following command to create an empty override file: sudo mkdir -p /etc/apt/apt.conf.d/ && echo 'DPkg::Post-Invoke {"";};' | sudo tee /etc/apt/apt.conf.d/99-disable-mandb. However, this is a blunt instrument that might disable all post-invoke hooks depending on syntax.
A safer, more targeted approach is to make the `mandb` trigger executable return true immediately without running. First, back up the trigger file: sudo cp /var/lib/dpkg/info/man-db.triggers /var/lib/dpkg/info/man-db.triggers.bak. Then, empty the file: sudo truncate -s 0 /var/lib/dpkg/info/man-db.triggers. Note that you will now need to manually run sudo mandb if you want your manual page index to be fully up to date with newly installed software.