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Ubuntu: disable automatic screen blanking

gsettings set org.gnome.settings-daemon.plugins.power sleep-inactive-battery-timeout 0
gsettings set org.gnome.settings-daemon.plugins.power sleep-inactive-ac-timeout 0
gsettings set org.gnome.desktop.screensaver idle-activation-enabled false
gsettings set org.gnome.settings-daemon.plugins.power idle-brightness 100
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DIY Surveillance Camera Recording

my crontab:

# start recording on boot
@reboot sleep 10; /usr/local/bin/startrecord.sh &> /dev/null

# restart every 10 minutes to create a new file
*/10 * * * * killall ffmpeg ; sleep 5 ; /usr/local/bin/startrecord.sh &> /dev/null

# purge old recordings
0 */6 * * * find /data/office-kamera -type f -mtime +12 -delete

/usr/local/bin/startrecord.sh

#!/bin/bash

#cam1
/usr/bin/ffmpeg \
 -rtsp_transport tcp -i rtsp://user:password@10.0.100.21:554/11 \
 -c:v mpeg2video -b:v 16M -bufsize 16M -maxrate 16M /data/office-kamera/$(date +\%Y-\%m-\%d.\%H-\%M).cam1.mpg \
 -c:a mp2 -ac 1 -ab 64k -ar 44100 \
 -y -update 1 -r 3 -f image2 -q:v 10 -vf "scale=iw/2:ih/2,transpose=2" /var/www/html/cam/cam1.jpg \
  &>/tmp/cam1.log &

Important: We use mpeg2 for a purpose! Forget matroska/h264/hs65. If your recording stops the hard way (power outage, crashing ffmpeg process, rising of the dead), no file trailer is written and you can NOT play or reconstruct your video when using mp4. For that reason we choose mpeg2, because you can still view fragments from a 20 year old CD-R that has been through a blender, or if you drop a thermonuclear weapon on your hard drive.

This will also put image frames to /var/www/html/cam/, where you can host a HTML document that displays your image and refreshes it via javascript if you like.

Finding you cameras RTSP URL is key. Just google "camera model rtsp url". If you have any questions feel free to ask. Consider donating via paypal if it works for you;)

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Reducing SAMBA Server / smbd load when transferring large files

We have a 4 core Intel i3 machine running ubuntu set up in our office, responsible for two jobs:

  • recording 5 security cameras to disk (ffmpeg)
  • being a general purpose fileserver.

The machine has a single, 3TB SATA disk and no RAID. The data on the machine doesn't matter, and doesn't need to be 100% available.

When we transferred a disk image (500GB) to it via SAMBA, it would run out of memory and start swapping, slowing down the already busy disk to a point where the machine would be completely unresponsive and need to be reset.

We fixed this by disabling oplocks in /etc/smb.conf:

[global]
oplocks = no

No further tuning reqired.

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How to remove all backups in Plesk for Linux

If you ever find yourself confronted with a Plesk system that is running out of disk space, and you just want to get rid off all the misconfigured "keep forever" backups, here's how to remove them all from the command line:

/usr/local/psa/admin/bin/pmm-ras --get-dump-list | egrep "name=\".*.xml" | awk -F '"' '{ print $2 }' | xargs -I {} /usr/local/psa/admin/bin/pmm-ras --verbose --debug --delete-dump --dump-specification={} --session-path=/var/log/plesk/PMM
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Windows 10: Creating boot partitions from scratch

First, boot a Windows 10 or Windows Server 2019 rescue CD and enter the command prompt.

Step 1a: If you have the 128MB + 100MB partitions and they are broken for some reason

diskpart

list disk
select disk
list part
# visually check you are about
# to do the right thing
select part 1
delete part override
select part 2
delete part override

Now continue with step 2.

Step 1b: If you don't have at least 228MB of unpartitioned space in front of your Windows partition

Boot the gparted Live CD and move your Windows partition to the right, 250MB is usually fine, then continue with step 2.

Step 2: Recreating the UEFI boot partitions and installing the bootloader:

create partition efi size=128
format quick fs=fat32 label="System"
assign letter="k"
create partition msr size=100
exit

bcdboot C:\windows /s k: /f UEFI

Step 3: Profit

That's all there is to it! Make sure to set your computer to UEFI ONLY, because it's past 2020.

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Xiaomi Robot Vacuum 4S2P DIY Battery Pack Repair

My Xiaomi Robot (V1) just sporadically shut down after around 20 Minutes of cleaning, stating "Error 14". I looked it up, and Error 14 stands for battery malfunction.

Since i own a lot of 18650 battery packs I'm able to build my own battery from old laptop battery 18650s, so I decided to upload the pinout of the Xiaomi Charging Pad

Solder your 4S cells here and you're good to go!

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gentoo/octane – A modern GNU/Linux system for the SGI Octane Workstation

It took about 6 months of work, and it's done: gentoo/octane 1.0 has been released.

Grab your copy here: gentoo-octane-v1.0-by-rephlex.tar.xz

It's basically a complete tarball of the system. So:

  • attach scsi disk to any machine or netboot the octane using root=/dev/nfs nfsroot=a.b.c.d/path/to/filesystem (if you're a tough guy)
  • prepare the octanes local disks
  • add tarball
  • set envvars (included)
  • profit

What works:

  • everything that would work in any random gentoo that is up-to-date as of April 2019 😉
  • Kernel 4.12 with audio, and all the funny devices inside the octane including impact graphics.

What doesn't work yet:

  • xf86-video-impact xorg module ;/ – see /etc/motd for how to achieve running xorg. It's ALMOST DONE!
  • Kernel newer than 4.12. The patches need to be tested and maybe adjusted, that's it.

IF YOU HAVE THOSE PATCHES, PLEASE CONTACT ME!

If you want to donate money, my paypal is rephlex@rephlex.de 😉

Awesome quickstart writeup by Alex Ernst:


root@SomeLinuxMachine:~# fdisk /dev/sdc

Command (m for help): p
Disk /dev/sdc: 136.8 GiB, 146815737856 bytes, 286749488 sectors
Disk model: BD1468A4C5
Geometry: 255 heads, 63 sectors/track, 17849 cylinders
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: sgi

Device         Start       End   Sectors   Size Id Type       Attrs
/dev/sdc1    2097153 278921217 276824065   132G  a SGI xfs     boot
/dev/sdc2  278921218 286744184   7822967   3.7G 82 Linux swap  swap
/dev/sdc9          0   2097152   2097153     1G  0 SGI volhdr
/dev/sdc11         0 286744184 286744185 136.7G  6 SGI volume

root@SomeLinuxMachine:~# mount /dev/sdc1 -t ext4 /mnt
root@SomeLinuxMachine:~# cd /mnt

root@SomeLinuxMachine:/mnt# ln -s boot/linux linux
root@SomeLinuxMachine:/mnt# ln -s boot/linux vmlinux

root@SomeLinuxMachine:/mnt# cat /mnt/boot/arc.cf
linux {
 image system /linux;
 append "root=/dev/sdc1";
 append "rw";
 append "init=/sbin/init";
 append "console=/dev/ttyS0";
}

root@SomeLinuxMachine:/mnt# dvhtool -d /dev/sdc --unix-to-vh /mnt/usr/lib/arcload/sash64 sash64
root@SomeLinuxMachine:/mnt# dvhtool -d /dev/sdc --unix-to-vh /mnt/boot/linux linux
root@SomeLinuxMachine:/mnt# dvhtool -d /dev/sdc --unix-to-vh /mnt/boot/arc.cf arc.cf

root@SomeLinuxMachine:/mnt# dvhtool -d /dev/sdc --print-all
----- partitions -----
Part#  0, start 2097153, blks 276824065, type XFS
Part#  1, start 278921218, blks 7822967, type Linux Swap
Part#  8, start 0, blks 2097153, type Volume Header
Part# 10, start 0, blks 286744185, type Volume
----- bootinfo -----
Root partition: 0
Swap partition: 1
Bootfile: "/unix"
----- directory entries -----
Entry #0, name "sash64", start 4, bytes 141392
Entry #1, name "linux", start 281, bytes 11429200
Entry #2, name "arc.cf", start 22604, bytes 130

root@SomeLinuxMachine:~# cd
root@SomeLinuxMachine:~# umount /mnt
root@SomeLinuxMachine:~# sync


Command Monitor.  Type "exit" to return to the menu.

>> setenv SystemPartition xio(0)pci(15)scsi(0)disk(3)rdisk(0)partition(8)
>> setenv OSLoadPartition xio(0)pci(15)scsi(0)disk(3)rdisk(0)partition(8)
>> setenv OSLoadFilename linux
>> setenv OSLoader sash64

>> boot
1216+51120+768+4256+592 entry: 0xa80000005fff0000
ARCLoad version 0.5 (c) 2004-5 Stanislaw Skowronek
Loading configuration for 'linux'...
GRUB Filesystem Error FILE_NOT_FOUND: 'ArcOpen failed'
Loading xio(0)pci(15)scsi(0)disk(3)rdisk(0)partition(8)/linux...
Reading 9488032 bytes... OK.
Entering kernel.

login as: root
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Welcome to gentoo/octane 1.0!

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Preferred settings for Macs Fan Control on older iMacs that run hot and make funny noises

Yesterday I encountered a customers iMac which ran crazy hot on the backside. Macs Fan Control indicated that the PSU was running on 70°C and more, and something made a buzzing sound (like a wire dangling inside a fan, which was not the case).

So I decided to set up the fans manually, the Mac now runs much cooler and still it's not too loud.

Here's my settings:

Set everything to manual
ODD Fan is controlled by GPU Diode. 40°C – 75°C (this controls the right hand side of the iMac)
The HDD fan is controlled by the HDD temperature. We set it to 45°C – 55°C. If your disk runs hotter, you'll shorten its lifetime and jeopardize your data. This stuff is sitting in the middle of the iMac case.
OK, and this one here is most important. Set the CPU fan to be controlled by the PSU Primary temperature.

I learned that Apple did decide to "cool" the PSU by blowing the CPUs hot air onto it. Duh. So since we need to make sure the PSU does not overheat and melt your display panels LED strips on the right side, we set the CPU fan speed in relation to the PSU temperature. We want the PSU to be 40°C – 53°C. The CPU temperature will also stay in this healthy temperature range.

Download Macs Fan Control on the dev's website, on github, or from my local mirror (v4.1.12).

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Fix IcedTea "cannot grant permissions to unsigned JARs" error

In case you are a Linux user unsuccessfully trying to connect to your IPMI/LOM Console using IcedTea / OpenJDK 8 or newer, you will likely run into this error.

You know, because if you're a major hardware vendor selling expensive enterprise class servers, you don't care about your IPMI hardware once you sold it.

Here's how to fix the issue on the client side:

Find the java.security file. In my case it is located in /usr/lib/jvm/java-8-openjdk-amd64/jre/lib/security/java.security

Then find the row

jdk.jar.disabledAlgorithms=MD2, MD5, RSA keySize < 1024

Comment it out, copy it, delete the word "MD5".

jdk.jar.disabledAlgorithms=MD2, MD5, RSA keySize < 1024
jdk.jar.disabledAlgorithms=MD2, RSA keySize < 1024

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