Cannot login to MariaDB server with root account

Problem

You are trying to login to MariaDB with the root user, but even after resetting the password, it is still not possible to login.

Solution

It seems that certain MariaDB packages that come with Linux distributions use the unix_socket as the authentication method.

MariaDB [mysql]> SELECT user, host, plugin FROM user WHERE user='root';
+------+-----------+-------------+
| user | host      | plugin      |
+------+-----------+-------------+
| root | localhost | unix_socket |
+------+-----------+-------------+
1 row in set (0.00 sec)

Change the plugin as described here (https://stackoverflow.com/a/43424234) with the following:

MariaDB [mysql]> UPDATE mysql.user SET plugin = '' WHERE user = 'root';
Query OK, 1 row affected (0.00 sec)
Rows matched: 1  Changed: 1  Warnings: 0

Errors were encountered while processing: linux-image-3.13.0-128-generic

Problem

You are trying to install/remove a package but you always get an error message about linux message as above:

Solution

Try the following:

failed to execute ‘/lib/udev/socket:@/org/freedesktop/hal/udev_event’ ‘socket:@/org/freedesktop/hal/udev_event’

Problem

Looking at your /var/log/syslog you see entries every few seconds like the following:

Solution

Seems that hal is not used in newer Ubuntu versions, so you can remove it:

Taken from the answer here

ERROR: could not open extension control file “/usr/share/postgresql/9.3/extension/plr.control”: No such file or directory

Problem

You are trying to install the PL/R extension to PostgreSQL, after install R in your linux ubuntu development environment, but when trying to install the extension inside your PostgresSQL with:

you are getting the following error:

Solution

Install the necessary package for your PostgreSQL version with the following, and install the extension in your psql:

Docker error – error response from daemon: Cannot start container….is not within /var/lib/docker/aufs/mnt

Problem

You are trying to use an image from Docker in your Ubuntu 14.04 system, but you are getting a error like the following:

Solution

Your docker version is outdated (ie 1.0.1) so you would need to upgrade your docker installation.
There is a script for this (information from here):

After running the following you should be able to use your images as normal with: sudo docker run -t -i image/name bin/bash:

Project ERROR: Unknown module(s) in QT: webkitwidgets

Problem

You are trying to bundle install a Gemfile that includes the capybara-webkit gem, in an Ubuntu system but you get the following error:

Solution

It seems that the latest ubuntu versions are using QT version 5 instead of 4. So in order to be able to install the gem you would need to install the qt development libraries for version 5 like:

Remap CapsLock to Ctrl in Ubuntu

Problem

You would like to remap your Caps Lock key to Ctrl so it is easier to use as the ‘Prefix’ in tmux.

Solution

Go to System Settings -> Input Devices -> Keyboard -> Advanced
and tick first the ‘Configure keyboard options’ and then
in the ‘Ctrl key position’ select ‘Caps Lock as Ctrl’

Using Postfix to send out emails from development environment in Rails

Problem

You want to be able to send emails from your development enironment using Postfix in your (K)Ubuntu pc.

Solution

First you would need to install postfix:

and then you would need to change an option in postfix to not use tls, so change /etc/postfix/main.cf:

and change the smtpd_use_tls from yes to no:

restart your postfix server:

and then setup your config/development.rb as follows: