Arduino powered LED sign

Using an Arduino UNO and 8 strips of Neopixel ws2812 strips (60 LED/m) I was able to recreate the awesome LED sign created by Josh here: https://youtu.be/k-SYMPO8-f8

Needed some text to test it and picked the cf push haiku by Onsi Fakhouri:

cf push haiku here is my source code run it on the cloud for me i do not care how”

 

Expanded sources.list for Ubuntu server 18.04

By default, if the new installer is utilized when deploying Ubuntu server 18.04, the /etc/apt/sources.list will contain only two entries. This doesn’t cover much, so to expand it to be a bit more useful we replace it with:

deb http://jp.archive.ubuntu.com/ubuntu/ bionic main restricted
deb http://jp.archive.ubuntu.com/ubuntu/ bionic-updates main restricted
deb http://jp.archive.ubuntu.com/ubuntu/ bionic universe
deb http://jp.archive.ubuntu.com/ubuntu/ bionic-updates universe
deb http://jp.archive.ubuntu.com/ubuntu/ bionic multiverse
deb http://jp.archive.ubuntu.com/ubuntu/ bionic-updates multiverse
deb http://jp.archive.ubuntu.com/ubuntu/ bionic-backports main restricted universe multiverse
deb http://security.ubuntu.com/ubuntu bionic-security main restricted
deb http://security.ubuntu.com/ubuntu bionic-security universe
deb http://security.ubuntu.com/ubuntu bionic-security multiverse

Note that this is for Japan (“jp”). Change this to “us” or similar to match your region if not in Japan.

Set network settings with netplan

If your system is using netplan for network configuration, change settings in “/etc/netplan/50-cloud-init.yaml”:

DHCP:

jonas@kube-c1-n3:~$ cat /etc/netplan/50-cloud-init.yaml
network:
    ethernets:
        enp0s3:
            addresses: []
            dhcp4: true
    version: 2
jonas@kube-c1-n3:~$ sudo netplan apply

Static IP:
jonas@kube-c1-n3:~$ cat /etc/netplan/50-cloud-init.yaml
network:
    ethernets:
        enp0s3:
            addresses: [192.168.10.103/24]
            gateway4: 192.168.10.1
            dhcp4: no
    version: 2
jonas@kube-c1-n3:~$ sudo netplan apply

Note that “gateway4” should only be set for the default route interface.

Atom editor window appearing outside of screen boundaries

If one disconnects an external monitor / projector the Atom editor window has a tendency to show up outside of the screen boundaries – just as if the external monitor was still attached. It took a while to figure out how to get it back again:

  1. Select the Atom window (using Alt-Tab or mouse)
  2. Open the context menu with Alt-Space
  3. Select move using “m”
  4. Press any of the arrow keys
  5. The Atom window will now be possible to drag back to the main monitor using the mouse

This was mentioned in a GitHub thread here: https://github.com/atom/atom/issues/6939

 

sudo without password

Add the following line at the end of /etc/sudoers (just after “#includedir /etc/sudoers.d”):

username ALL=(ALL) NOPASSWD: ALL

In my case:

#includedir /etc/sudoers.d
jonas ALL=(ALL) NOPASSWD: ALL

Check swap on Ubuntu

jonas@yggdrasil:~$ sudo swapon --show
NAME      TYPE       SIZE USED PRIO
/dev/dm-2 partition 11.9G   0B   -1
jonas@yggdrasil:~$

jonas@yggdrasil:~$ sudo free -m
              total        used        free      shared  buff/cache   available
Mem:          11925        9240         911         305        1773        2110
Swap:         12195           0       12195
jonas@yggdrasil:~$ 

Wipe USB drive in Linux by overwriting with random data

Handy way to wipe a USB drive in Linux using dd and /dev/urandom:

jonas@yggdrasil:~$ sudo dd if=/dev/urandom of=/dev/sdc bs=4k
dd: error writing '/dev/sdc': No space left on device
15163393+0 records in
15163392+0 records out
62109253632 bytes (62 GB, 58 GiB) copied, 2227.1 s, 27.9 MB/s

Of course, make sure /dev/sdX is the USB device you want to wipe. DD isn’t being referred to as the “Disk Destroyer” for nothing 🙂