Ubuntu 20.04: annoying popup ‘Authentication is required to run gvfsd-admin daemon’

If you get the above popup, and it is impossible to get it to go away (cancel does nothing, authenticate hangs…), here is a quick solution to get rid of it:

Press ALT+F2, enter ‘r’ (without the quotes) in the command box and press enter. This will restart Gnome and the window will be gone. Your running apps keep running!


Nextcloud: my files view is empty???

After a serious upgrade of my NextCloud server, I had the strange phenomenon that my files view was completely empty. Tried everything, nothing worked. In the end the cause was proven to be an extra folder in de data directory of Nextcloud.

I had copied all data from a usb drive and put it in a __filesfrompreviousserver folder in the /var/snap/nextcloud/common/nextcloud/data folder, which is the folder where NextCloud stores its data.

I never thought that would cause problems, but apparently it does. Once I removed the folder everything was fine again.


Ubuntu: external screen goes black, but ubuntu is still using 2 screens

Today I had the problem that my external screen was only showing a nice shade of black. However, several programs were running on that screen, and I could not just reboot the laptop without losing much work.

To fix this (it did fix it for me, your mileage may vary), open a terminal window (Ctrl + Alt + t) and type the following command:


After this, I had my second screen back.


Activate the Master Control Panel (AKA God Mode)

What is this? MCP adds an icon to your desktop that gives you near instant access to nearly every Windows setting available.

Activating this is really simple: just create a new folder on your desktop (right-click and select New -> Folder), and name it “GodMode.{ED7BA470-8E54-465E-825C-99712043E01C}”

This will create a new folder with the following icon:

Double-clicking this icon will open a list of settings.

Linux Zentyal

Zentyal: how to change password expiry options

Zentyal is a great replacement for Windows domains, but in the webinterface there is currently (version 6) no option to change the password expiry settings.

To change them anyway, open a linux terminal on the Zentyal server and use the samba-tool utility

samba-tool domain passwordsettings set --max-pwd-age=0

This will turn off password aging. Change the 0 to the number of days you want to set it to expire to anything else than the default 365 days. Have look at the help page or manpage for samba-tool to see more options. If the command executes successfully, you will see the following text:

Maximum password age changed!
All changes applied successfully!

and you are done!

Linux: using tmux to start server processes

If you want to start a process or command on a linux server and want to return later to check if it ran ok, or if it is still running, then the tmux tool is very handy.

Tmux can do many more things (like split a terminal window in multiple panes), but that is outside the scope of this article.

To start a new session on your server (once you are connected to the server with ssh), type:

tmux new -s mysession

where ‘mysession’ is the name you want to use

Now start whatever command you want.

If you want to leave your session, but keep everything running so you can check back at a later time, press Ctrl-b d.

To list all detached sessions, use the following command:

tmux ls

No you can reattach to a session using the following command:

tmux attach -t mysession

Backup Linux MySQL

MySQL: backup your databases

I have put an interesting bash script to backup your database on my git page. You can find it here on

Feel free to use and modify it however you please. If you add interesting functionality, or find any annoying bugs, then some feedback through github would be nice.

You can use this script interactively by just typing ./ in the scripts folder, or you can find out about all the parameters it accepts by using the -h switch.

The script also allows you to create config files with all necessary info to backup a database and then run or schedule it with

/home/backupadmin/scripts/ -c /home/backupadmin/configs/mycompanydatabase.config > /var/log/backupdatabase.log

Where mycompanydatabase.config is a textfile containing something like this:

databasehost =
databaseuser = backupuser
databasepassword = myverysecretdatabasepassword
backupmode = DATA
targetdirectory = /mnt/backupserver/backups/databases
tempdirectory = /tmp
comment = daily backup


MySQL: get value of last auto-increment field

If you use an auto increment field (autonumbering) in your database table, you can find the last generated number by performing the following query :

select last_insert_id();

This will get the last id for the current connection. If you close the connection you can’t get the number again, and it will only return the last number for *your* connection. It is kept on a per-connection basis.

Linux MySQL

Using MySQL (basics)

This article assumes you are using linux, and mysql has already been installed and configured.

Starting the interactive environment

Start a linux terminal (CTRL+ALT+T) and type the following:

mysql --user=<username> --password=<password>

Where <username> is the name of the user that has access to mysql, and <password> is his/her/their password.

Creating a database

Once you have started the interactive environment as explained above, you can start creating databases by typing the following command:

create database mydatabase;

Please replace mydatabase with the name of the database you want to create.

Defining permissions

To grant a user all rights on all databases, you can use the following command:

grant all privileges on *.* to 'username'@'localhost'  identified by 'mypassword' with grant option;

Of course this is not the safest setup, you should always limit the privileges as much as possible. So to grant a user only select on all databases, you could use:

grant select on *.* to 'username'@'localhost'

Suppose you want to give select access on one specific table in one database, to a user coming from any host:

grant select on `mydatabase`.`mytable` to 'username'@'%';

Notice the backticks around the databasename, and the tablename. And the % sign to indicate any host.

Showing permissions for a user

show grants for username@localhost;

Using a database

Before you can access a database, you have to tell MySQL which database you want to use:

use mydatabase;

Replace mydatabase with the name of the database you want to access.

Creating a table

Suppose you want to create a table ‘products’ in database ‘mydatabase’ with the following fields:

'id'          : a unique recordkey filled automatically
'name'        : the name of the product
'description' : a longer text describing the item
'stock'       : a number, no decimals
'price'       : number, two decimals
'dateupdate'  : date field

The primary index will be on the unique id, a secondary index will be on name.

To create this table, use the following command:

use mydatabase;
create table products (
name CHAR(255),
description TEXT,
stock BIGINT,
price DECIMAL(9,2),
dateupdate DATE,
PRIMARY KEY (id), KEY(name)

A short explanation:

the field ‘id’ is created as an INTeger, can NOT be NULL, and is AUTOmatically INCREMENTed, ‘name’ can contain 255 CHARacters, ‘description’ can contain a large TEXT, ‘stock’ is a BIG INTeger, so it can’t have a decimal point, ‘price’ is 9 characters long, 2 after the decimal point.

List all tables in a database

To list all tables in database mydatabase use the following commands:

use mydatabase;
show tables;

Show the structure of a MySQL table

To show the structure of table ‘products’ use the following command:

use mydatabase;
describe products;

This will get an overview similar to the one below:

| Field      | Type         | Null | Key | Default | Extra          |
| id         | int(11)      |      | PRI | NULL    | auto_increment |
| name       | varchar(255) | YES  | MUL | NULL    |                |
| description| text         | YES  |     | NULL    |                |
| stock      | bigint(20)   | YES  |     | NULL    |                |
| price      | decimal(9,2) | YES  |     | NULL    |                |
| dateupdate | date         | YES  |     | NULL    |                |

Backup and restore of MySQL databases

There will be a separate post for this, including a handy little script to automate this.

A simple way to backup the database is type the following command on the bash prompt (Not inside the mysql interactive environment)

mysqldump mydatabase > backup_mydatabase.sql

Replace ‘mydatabase’ by the name of the database you want to backup, and ‘mydatabase.sql’ by the name of the backupfile.

To restore this you open the mysql interactive environment, create an empty database as explained below, select the database and then process the backup file. You can do this as follows:

create database mydatabase;
use mydatabase;
source backup_mydatabase.sql

Replace ‘mydatabase’ with the name of your database and ‘mydatabase.sql’ with the name of you backup file. It is best to use the full path here (e.g. /home/dbadmin/backups/backup_products_database.sql)