Category: Utilities

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Temporarily Force Ubuntu to IPV4

Refer: https://linuxconfig.org/how-to-disable-ipv6-address-on-ubuntu-20-04-lts-focal-fossa

sudo sysctl -w net.ipv6.conf.all.disable_ipv6=1
sudo sysctl -w net.ipv6.conf.default.disable_ipv6=1

The above commands will temporarily disable IPv6, meaning that the settings will not persist after reboot. To re-enable IPv6 reboot your system or execute the above commands again however reverse the logic and change 1 to 0

In case you need more permanent solution to disable IPv6 even after system reboot follow the steps below:

As an administrative user open up the /etc/default/grub file using your favourite text editor and make to following changes:

FROM:
GRUB_CMDLINE_LINUX_DEFAULT=""
TO:
GRUB_CMDLINE_LINUX_DEFAULT="ipv6.disable=1"

Once ready update Grub menu:

sudo update-grub

In case you need to re-enable the IPv6 network addresses simply remove the ipv6.disable=1 from the /etc/default/grub file and run the update-grub command.

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Compare Two Text Files

Refer: https://stackoverflow.com/questions/746458/how-to-show-lines-in-common-reverse-diff" href="https://stackoverflow.com/questions/746458/how-to-show-lines-in-common-reverse-diff">https://stackoverflow.com/questions/746458/how-to-show-lines-in-common-reverse-diff

comm -1 -2 file1.sorted file2.sorted

where file1 and file2 are sorted and piped into *.sorted

Here's the full usage of comm:

comm [-1] [-2] [-3 ] file1 file2
-1 Suppress the output column of lines unique to file1
-2 Suppress the output column of lines unique to file2
-3 Suppress the output column of lines duplicated in file1 and file2

The comm command (short for "common") may be useful comm - compare two sorted files line by line

find lines only in file1

comm -23 file1 file2

find lines only in file2

comm -13 file1 file2

find lines common to both files

comm -12 file1 file2

The man file is actually quite readable for this.

comm -23 OLCI_K229.csv OLCI_EDOCS.csv
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Split MP3 Audio and Convert M4B to MP3

Refer: https://askubuntu.com/questions/1264779/how-to-split-an-mp3-file-by-detecting-silent-parts

Use ffmpeg to convert m4b to mp3

Refer: Refer: https://superuser.com/questions/173571/how-to-convert-m4b-files-to-mp3

ffmpeg -i "file.m4b" -acodec libmp3lame -ar 22050 "file.mp3"

Install Software

sudo apt install -y mp3splt

Sample Usage:

mp3splt -s your.mp3

If it creates TOO MANY TRACKS

Mp3splt will try to automatically detect splitpoints with silence detection and will split all tracks found with default parameters.

mp3splt -s -p th=-50,nt=100 your.mp3

passing desired parameters, splitting 100 tracks (or less if too much) with the most probable silence points at a threshold of -50 dB.

In this example we are setting the minimum silence to 4.9 seconds and still

mp3splt -s -p th=-40,min=4.9,nt=100 'The Catcher in the Rye By Salinger.mp3'
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LED How to Determine Positive and Negative

On the physical LED, the longer lead (or leg) of the LED is the anode. The cathode is marked on the rim of the LED body with a flat area shown in the diagram. Another way to tell which lead is the anode and which is the cathode is to look at the two plates at the end of the leads inside the body of the LED.