Dimmer – Reduce your computer screen brightness

It has started getting really hot in the UK and my flat is about 28 degrees at night. This means I have been sitting in a dark flat with all the windows and doors open.

This works well but If I want to work on my computer then the lowest brightness level is still too bright. I did some searching around and a quality piece of software “Dimmer“.

This is a really simple exe you unzip and run. Once running it will reduce the contrast of the screen. This in effect reduces the brightness by turning white colours greyer.

I have been using this for a couple days and had to recommend it as a quality piece of software. So here I am posting about it so I remember it for the future.

During this heatwave I have turned off the Raspberry PI cluster so it isn’t running while being exposed to this ambient heat and humidity. I have a couple weeks more blog posts about Raspberry Pi’s so this shouldn’t affect the weekly blog.

Raspberry Pi Read-only file system Fix Solved

If you are getting “Read-only file system” on your Raspberry Pi when mounting drives there is a simple fix.

chewett@bunker-master2:/mnt/wd500$ touch test.txt
touch: cannot touch ‘test.txt’: Read-only file system

I noticed this happening when I tried to mount and work on my external hard drive. This is formatted with the NTFS filesystem.

I did some research and it turns out that by default Raspbian Jessie (as of 13/06/2017) does not include the ability to write to NTFS drives. To add this ability you can run the below command

sudo apt-get install ntfs-3g

This installs the NTFS driver which will allow you to also write to NTFS drives.

This issue will occur for anything using the underlying NTFS driver. I found this issue when I was mounting a veracrypt volume on the Raspberry Pi.

Veracrypt was installed by following my guide to install Veracrypt on the Rasperry Pi. Now I have resolved this problem I will be able to access my external drives on the Raspberry Pi.

VCHI initialization failed Raspberry Pi Fixed

vcgencmd get_mem arm VCHI initialization failed
Example showing VCHI initialization failed error

If when running vcgencmd on a raspberry pi you get VCHI initialization failed then you need to add the video group to your user. The vcgencmd tool requires you have this group role so without it, it will give VCHI initialization failed.

To add the user group to your user you can run:

sudo usermod -aG video <username>

Where <username> is the user you want to run the vcgencmd command with. This command adds the video group to the the user you specify.

Once you have ran the command any new logins will run the command successfully. Logging out and back into the pi will let you use the command.

Why this problem occurs

This issue happens when you try and use the vcgencmd command with a user that isn’t a member of the video group. This typically happens when you create a new user for the raspberry pi and don’t give it the same groups that the pi user has.

The solution above fixes this by adding the correct video group to the created user.

Mysql workbench working with key based exchange mechanisms

It appears newer linux sshd configs (fedora 22) by default include a smaller set of key exchange based mechanisms that they have turned on.

This means that it gives errors saying it is unable to connect to the server. To fix this you need to enable some of the older key exchange mechanisms,

Adding this line to /etc/ssh/sshd_config and restarting the sshd server will fix it

KexAlgorithms curve25519-sha256@libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1

Credits to: http://serverfault.com/questions/692060/mysql-workbench-with-debian-jessie-tcp-ip-over-ssh-does-not-work

Install Virtualbox guest additions on Fedora 21 XFCE

Installing via the normal route didn’t work and meant I couldn’t easily resize the screen. Doing the below allowed me to use the resize easily.

  1. Install rpmfusion on fedora
  2. run `sudo yum install akmod-VirtualBox VirtualBox-guest`
  3. run `cd /usr/src/akmods`
  4. run `sudo rpm -ivh VirtualBox-*.rpm`

Once this was installed, rebooting will give you access to shared folders and fullscreen mode

Found the fix on the fedora forums for fedora 19

Selection/Click and drag doesnt work in Gmail – Opera

In opera normally click and drag or selection doesn’t work. This is because in opera Gmail serves up some CSS that breaks the display and stops you clicking and dragging text.

To fix this, you can enable opera’s list of JavaScript changes, to make popular sites work. This is done by visiting: http://www.opera.com/docs/browserjs/

Could not access network location \Hewlett-Packard\\

When trying to install MySQL Server it failed with the message “Could not access network location \Hewlett-Packard\\”

After some searching it turns out this is a common issue where HP have inserted a registry entry with the install path of “\Hewlett-Packard\\” which isnt a valid location. This can be resolved by removing this entry. This is safe to do so.

If you dont know what the registry is, you probably want to talk to someone who does or do some research, but using the search tool to find “\Hewlett-Packard\\” and delete the entry should fix the issue. It could be in a number of places but will likely be under an “uninstall” path.

As usual, when playing with the registry, use caution, ask others if unsure, and back it up.

Full error log mysql installer gave me:

1: Action 11:31:29: INSTALL.
1: 1: MySQL Server 5.6 2: {0B9D4C33-AC1B-4973-B754-FE9EAB03D327}
1: Action 11:31:29: FindRelatedProducts. Searching for related applications
1: Action 11:31:29: AppSearch. Searching for installed applications
1: Action 11:31:29: LaunchConditions. Evaluating launch conditions
1: Action 11:31:29: ValidateProductID.
1: Action 11:31:29: CostInitialize. Computing space requirements
1: Action 11:31:29: FileCost. Computing space requirements
1: Action 11:31:29: CostFinalize. Computing space requirements
1: Could not access network location \Hewlett-Packard\\.
1: Could not access network location \Hewlett-Packard\\.
1: 1: MySQL Server 5.6 2: {0B9D4C33-AC1B-4973-B754-FE9EAB03D327} 3: 3
1: Final actions.
1: Install error