Upgrading avahi-dnsconfd on Ubuntu

This is how I got around problem that occurred when I was updating a virtualised Ubuntu 16.04 instance that I have. My usual way to do this is using apt-get or apt from the command line and the process halted because a pre-removal script for the upgrade of avahi-dnsconf failed. The cause was its not disabling the avahi daemon beforehand so I need to execute the following command before repeating the operation:

sudo systemctl disable avahi-daemon

Once the upgrade had completed, then it was time to re-enable the service using the following command:

sudo systemctl enable avahi-daemon

Ideally, this would completed without such manual intervention and there is a bug report for the unexpected behaviour. Hopefully, it will be sorted soon but these steps will fix things for now.

Making pages of new documents look right in LibreOffice Writer on wide screens

My recent move from Linux Mint 17.3 to Linux Mint 18.1 brought with it version 5.3.0.3 of LibreOffice. What that brought was an oddity where the default blank document in a fresh LibreOffice Writer session had its only page displayed to the right within the application window. To me, this looks like a bug even if I have a 24″ computer screen.

After some searching, I found a solution that gets a single page displayed in the centre of the application window and not offset to the right as it was. The first step is to go to the Zoom entry within the View menu. Within the sub-menu that is spawned, you need to click on the Zoom… entry to get a dialogue box. That has two columns and the setting that needs changing is under the one named View Layout. For whatever reason, the Columns setting was highlighted with 2 being selected as the number of columns. Choosing the Single Page option instead sorted the problem on clicking the OKĀ button to dismiss the dialogue and the one named Automatic also appears to work. Quite why such an odd default was selected in the first is beyond me though.

Trying out a new way to upgrade Linux Mint in situ while going from 17.3 to 18.1

There was a time when the only recommended way to upgrade Linux Mint from one version to another was to do a fresh installation with back-ups of data and a list of the installed applications created from a special tool.

Even so, it never stopped me doing my own style of in situ upgrade though some might see that as a risky option. More often than not, that actually worked without causing major problems in a time when Linux Mint releases were more tightly tied to Ubuntu’s own six-monthly cycle.

In recent years, Linux Mint’s releases have kept in line with Ubuntu’s Long Term Support (LTS) editions instead. That means that any major change comes only every two years with minor releases in between those. The latter are delivered through Linux Mint’s Update Manager so the process is a simple one to implement. Still, upgrades are not forced on you so it is left to your discretion as to when you need to upgrade since all main and interim versions get the same extended level of support. In fact, the recommendation is not to upgrade at all unless something is broken on your own installation.

For a number of reasons, I stuck with that advice by sticking on my main machine with Linux Mint 17.3 instead of upgrading to Linux Mint 18. The fact that I broke things on another machine using an older method of upgrading provided even more encouragement.

However, I subsequently discovered another means of upgrading between major versions of Linux Mint that had some endorsement from the project. There still are warnings about testing a live DVD version of Linux Mint on your PC first and backing up your data beforehand. Another task is ensuring that you are upgraded from a fully up to data Linux Mint 17.3 installation.

When you are ready, you can install mintupgrade using the following command:

sudo apt-get install mintupgrade

When that is installed, there is a sequence of tasks that you need to do. The first of these is to simulate an upgrade to test for the appearance of untoward messages and resolve them. Repeating any checking until all is well gets a recommendation. The command is as follows:

mintupgrade check

Once you are happy that the system is ready, the next step is to download the updated packages so they are on your machine ahead of their installation. Only then should you begin the upgrade process. The two commands that you need to execute are below:

mintupgrade download
mintupgrade upgrade

Once these have completed, you can restart your system. In my case the whole process worked well with only my PHP installation needing attention. A clash between different versions of the scripting interpretor was addressed by removing the older one since PHP 7 is best kept for sake of testing. Beyond that, a reinstallation of VMware Player and the move from version 18 to version 18.1, there hardly was anything more to do and there was next to no real disruption. That is just as well since I depend heavily on my main PC these days. The backup option of a full installation would have left me clearing up things for a few days afterwards since I use a bespoke selection of software.

Updating Piwik using the Linux Command Line

Because updating Piwik using its web interface has proved tempestuous, I have decided update the self-hosted analytics application an ssh session. The production web servers that I use are hosted on Linux systems so that is why any commands apply to the Linux or UNIX command line only. What is needed for Windows servers may differ.

The first step is to down the required ZIP file with this command:

wget https://builds.piwik.org/piwik.zip

Once the download is complete, the contents of the ZIP archive are extracted into a new subfolder. This is a process that I carry out in a separate folder to that where the website files are kept before copying everything from the extract folder in there. Here is the unzip command and the -o switch turns on overwriting of any previously existing files:

unzip -o piwik.zip

Without the requirement folder in web server area updated, the next step is to do the actual system update that includes any updates to the Piwik database that you are using. There are two commands that you can use once you have specified the location of your Piwik installation. The second is needed when the first option cannot find where the PHP executable is stored. My systems had something more specific than these because both PHP 5.6 and PHP 7.0 are installed. Looking in /usr/bin was enough to find what i needed to execute in place of php below. Otherwise, the command was the same.

./[path to piwik]/console core:update

php [path to piwik]/console core:update

While the upgrade is ongoing, it prompts you to permit it to continue before it goes and makes changes to the database. This did not take long on my systems but that depends on how much data there is. Once, the process has completed, you can delete any extraneous files using the rm command.

Reloading .bashrc within a BASH terminal session

BASH is a command-line interpretor that is commonly used by Linux and UNIX operating systems. Chances are that you will find find yourself in a BASH session if you start up a terminal emulator in many of these though there are others like KSH and SSH too.

BASH comes with its own configuration files and one of these is located in your own home directory, .bashrc. Among other things, it can become a place to store command shortcuts or aliases. Here is an example:

alias us=’sudo apt-get update && sudo apt-get upgrade’

Such a definition needs there to be no spaces around the equals sign and the actual command to be declared in single quotes. Doing anything other than this will not work as I have found. Also, there are times when you want to update or add one of these and use it without shutting down a terminal emulator and restarting it.

To reload the .bashrc file to use the updates contained in there, one of the following commands can be issued:

source ~/.bashrc

. ~/.bashrc

Both will read the file and execute its contents so you get those updates made available so you can continue what you are doing. There appears to be a tendency for this kind of thing in the world of Linux and UNIX because it also applies to remounting drives after a change to /etc/fstab and restarting system services like Apache, MySQL or Nginx. The command for the former is below:

sudo mount -a

Often, the means for applying the sorts of in-situ changes that you make are simple ones too and anything that avoids system reboots has to be good since you have less work interruptions.