How to Install and Configure NVIDIA Graphics Card in FreeBSD

 

[SKIP - NOT USED] Install driver for NVIDIA Graphics Card

pkg install nvidia-driver

sysrc kld_list+="nvidia nvidia-modeset"

sysrc linux_enable="YES" 

[SKIP - NOT USED] Configure the NVIDIA driver in a configuration file

cat >> /usr/local/etc/X11/xorg.conf.d/20-nvidia.conf << EOF
Section "Device"
    Identifier "Card0"
    Driver     "nvidia"

    BusID     "pci0:0:1:0"  
EndSection

EOF

[SKIP - NOT USED] NVIDIA configuration (it creates /etc/X11/xorg.conf)

pkg install nvidia-xconfig

nvidia-xconfig

How to get VMs with specific custom attribute?

Here is the Onliner to list VMs with custom attribute "Last Backup" ...

Get-VM | Select-Object Name, @{N='LastBackup';E={($_.CustomFields | Where-Object {$_.Key -match "Last Backup"}).Value}} | Where-Object {$_.LastBackup -ne $null -and $_.LastBackup -ne ""}

and here is the another one to count the number of such VMs ...

Get-VM | Select-Object Name, @{N='LastBackup';E={($_.CustomFields | Where-Object {$_.Key -match "Last Backup"}).Value}} | Where-Object {$_.LastBackup -ne $null -and $_.LastBackup -ne ""} | Measure-Object | Select-Object Count

 

How to get all VMs restarted by VMware vSphere HA? PowerCLI OneLiner below will do the magic ...

Get-VIEvent -MaxSamples 100000 -Start (Get-Date).AddDays(-1) -Type Warning | Where {$_.FullFormattedMessage -match "restarted"} | select CreatedTime,FullFormattedMessage | sort CreatedTime -Descending | Format-Table

How to compress PDF file in Linux

I'm using Linux Mint with xsane for scanning documents on my old but still good Canon MX350 printer/scanner. Scans are saved as huge PDF documents (for example 50 MB) and I would like to compress it to consume much less disk space.

Install Ghostscript

apt install ghostscript

Compress the file input.pdf

gs -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS=/ebook -dNOPAUSE -dQUIET -dBATCH -sOutputFile=output_compressed.pdf input.pdf

Let's break down these options

• -sDEVICE=pdfwrite: Tells Ghostscript to output a PDF file.
• -dCompatibilityLevel=1.4: Sets the PDF version. Version 1.4 is quite old but widely compatible and often allows for good compression. You can try 1.5 or 1.6 for slightly more modern features and potentially better compression in some cases.
• -dPDFSETTINGS=/ebook: This is the main compression control. As mentioned, /ebook usually gives a good balance.
• -dNOPAUSE -dQUIET -dBATCH: These make Ghostscript run silently and non-interactively.
• -sOutputFile=output_compressed.pdf: Specifies the name of the compressed output file.
• input.pdf: original 50 MB PDF.

Lossy compression (322x) from 50 MB to 155 KB without any visible degradation is worth to keep cloud (Google drive) costs low.

My VIM configuration file

My preferred editor in unix-like systems is vi or vim. VI is everywhere and VIM is improved for scripting and coding.

VMware VCF's SDDC Backup over sftp

You can do a native VCF SDDC Manager backup via SFTP protocol. SFTP is a file transfer protocol that operates over the SSH protocol. When using SFTP for VMware VCF's backup, you're effectively using the SSH protocol for transport.

For VCF older than 5.1, you have to allow ssh-rsa algorithm for host key and user authentication on your SSH Server.

It is configurable in SSH Daemon Configuration (/etc/ssh/sshd_config) on your backup server should have following lines to allow ssh-rsa algorithm for host key and user authentication.

# add ssh-rsa to the list of acceptable host key algorithms

HostKeyAlgorithms +ssh-rsa

 

# allow the ssh-rsa algorithm for user authentication

PubkeyAcceptedAlgorithms +ssh-rsa

 

 

This should not be necessary for SDDC Manager in VCF 5.1 and later.

 

RaspberryPi - GPIO control over Web Interface

How to use RaspberryPi inputs and outputs? The easiest way is to use the GPIO pins directly on the RaspberryPi board.

Hardware

Raspberry Pi has 8 freely accessible GPIO ports. which can be controlled. In the following picture they are colored green. 

GPIO ports

Attention!!! GPIO are 3.3V and do not tolerate 5V !! Maximum current is 16mA !! It would be possible to use more of them by changing the configuration.

Software

First you need to install the ligthhttpd (or apache ) server and PHP5:
sudo groupadd www-data
sudo apt-get install lighttpd
sudo apt-get install php5-cgi
sudo lighty-enable-mod fastcgi
sudo adduser pi www-data
sudo chown -R www-data:www-data /var/www
In the lighthttpd configuration

you need to add:
bin-path" => "/usr/bin/php5-cgi
socket" => "/tmp/php.socket"

Now you need to restart lighthttpd:
sudo /etc/init.d/lighttpd force-reload

This will run our webserver with PHP.

Now we get to the actual GPIO control. The ports can be used as input and output. Everything needs to be done as root.

First you need to make the port accessible:
echo "17" > /sys/class/gpio/export

Then we set whether it is an input (in) or output (out):
echo "out" > /sys/class/gpio/gpio17/direction

Set the value like this:
echo 1 > /sys/class/gpio/gpio17/valu

Read the status:
cat /sys/class/gpio/gpio17/value

This way we can control GPIO directly from the command line. If we use the www interface for control, we need to set the rights for all ports so that they can be controlled by a user other than root.
chmod 666 /sys/class/gpio/gpio17/value
chmod 666 /sys/class/gpio/gpio17/direction