Darren had been having problems with Kontact and was unable to use the Calendar; John suggested he locate the Korganizer
std.ics file which can be opened in other calendar programs. John had done something similar when there were problems some years ago with Kontact.
John went on to share a script for backing up
## Keeping a regular backup of mysql/mariadb databases
## Decide on a suitable folder in /home to hold the backup, e.g. /home/<user>/Data, and a regular frequency, e.g. weekly
sudo rm backup.sql
## Because backup.sql is in a folder which is backed up elsewhere, this should cause no problems
sudo mysqldumpmysqldump --user=root --password --lock-tables --databases -B [space separated list of databases] > backup.sql
## The above takes account of changes to authentication in mariadb; --all-databases without a list can be used with mysql
## The resulting file has the attributes
-rw-r--r-- 1 root root
## For additional protection, if necessary,
sudo chmod 600 backup.sql
## Delete all commands from the past week
## Backup the folder which contains the new backup file
## If you need to restore the backup, as mysql user root, from within mysql
## Go back through all the changes recorded in .mysql_history for the past week
## and re-enter them in chronological order to restore your databases to their up-to-date state
mysql/mariadb databases are held in
/var, they need to be backed up to somewhere else, e.g. within
/home if you are doing regular backups of
/home. Deleting the old backup file first seems to be necessary. Clearing out
.mysql_history every time you backup means that, if you need to restore the database, you can restore it fully to its current state by re-entering the relevant commands in
.mysql_history since the last backup after you have restored the database.
You can use this technique to move the databases from an old to a new computer; in fact, John’s databases contain entries from as long ago as 1986 when he first started using dBASE. The only things he had to do in order to import his dBASE databases into
mysql was to put all the dates into
mysql date format and insert
\N into all the empty cells, both of which he did with dBASE scripts, and then import them as CSV files.
John also mentioned that, just before Christmas, Konqueror, the earlier KDE web browser, had been upgraded with Qt WebEngine and so had now recovered its web browsing capabilities. Several years ago KDE had said that they were dropping Konqueror as a web browser and adopting Qupzilla, renamed as Falkon, as its web browser.
Brian demonstrated Jellyfin which he uses to manage movies and music; it downloads the artwork relevant to each item and allows searching on a wide range of criteria. He prefers it to Kodi which has its own program to show videos and categorises movies. David commented that he had Plex running on an nginx server.
David has finally received the PCA9685 server board enabling him to create a 3D printed rack and pinion (such as this one on Thingyverse) using his Ender-3 Pro 3D Printer in order to change a model railway point; at present, there is too much movement in the rack; so he needs to find a way to create movement only over the last eighth of an inch.
He is also looking at an ESP32-Cam Pan&Tilt stand for which there are instructions, using Arduino, at Random Nerd Tutorials; it uses the STL file format and you can use a webpage to control the servo. He noted that, when you plug in the servo, it goes to a set position which is very useful for starting things off.
Other projects he had explored included a Laser Video & Transparency Projector.
He had also printed a 2½ to 3½ hard drive adapter but had come across a problem fitting the screws which, for the 3½ hard drive, requires US rather than metric screws!
He also demonstrated an adapter for an old PC power supply which gives 12V, 5V and 3.3V.
He uses OpenSCAD for designing things.
Bernard wondered about using the principles of David’s rack and pinion to move a camera so that it tracked particular objects in the sky and he and David discovered a number of ideas, including Poor man’s telescope tracker, Star tracker and Geared tracker for astrophotography.Past Meetings