add systray to elemtary os

Elementary OS 5 comes with a very limited systray functionality that needs to be fixed. For this you need to install wingpanel-indicator-ayatana that can be installed via a PPA and change autostart config of the indicator app.

Install wingpanel-indicator-ayatana

sudo add-apt-repository ppa:yunnxx/elementary
sudo apt update
sudo apt install indicator-application wingpanel-indicator-ayatana

Change autostart config

Open the config file with

sudo vim /etc/xdg/autostart/indicator-application.desktop

and change the line

OnlyShowIn=Unity;GNOME;

to

OnlyShowIn=Unity;GNOME;Pantheon;

Then reboot your machine and you should have a systray that displays your application icons too.

Nvidia GeForce GTX 2070 Super under Linux

I installed a Nvidia GeForce GTX 2070 Super (https://geizhals.at/msi-geforce-rtx-2070-super-gaming-x-trio-v372-257r-a2091022.html) in my system removing a GTX 980. The system has a dual boot with Win10 and elementary OS 5. Both system were using the nvidia native driver. There was no extra effort neither in Windows nor elementary OS. Windows took about a minute to switch to the correct driver after starting with 1024×768. Elementary OS wasn’t interested at all in the change. Conclusion: Using a GeForce GTX 2070 Super works like a charme under Windows and Linux. At least for me and my system configuration. So please don’t blame me if you are running into troubles.

You can find that article on amazon under https://amzn.to/2A3l8Bh.

How to use Epson POS printer TM-T20II under linux

Getting an epson pos printer up and running under linux is very easy:

# add current user to lp group (requires relogin to work properly)
sudo usermod -a -G lp $USER

# for TM-T20II add udev rule (optional in my case):
echo 'SUBSYSTEM=="usb", ATTRS{idVendor}=="04b8", ATTRS{idProduct}=="0e15", MODE="0664", GROUP="lp"' > sudo tee -a /etc/udev/rules.d/99-escpos.rules
sudo service udev restart

# install pip and pipenv
sudo apt install python3-pip libopenjp2-7
pip3 install --user pipenv

# install download python-escpos and submodules
git clone https://github.com/python-escpos/python-escpos.git
cd python-escpos
git submodule update --init --recursive

# install including deps
pipenv install -e .

Now you should be ready to use the installation. From your installation repository run a pipenv shell by using “pipenv shell” or simply run “pipenv run python your-script_.py” to run a script directly.

Here is an example script:

from escpos.printer import Usb

# see https://github.com/python-escpos/python-escpos/blob/development/src/escpos/escpos.py

""" Seiko Epson Corp. Receipt Printer (EPSON TM-T20II) """
p = Usb(0x04b8, 0x0e15, 0, profile="TM-T88II")

p.set(bold=True, underline=1, align='center', custom_size=True, width=2, height=2)
p.textln("Hello world")
p.ln(count=1)
p.set()
p.textln("this is a test")

p.set(align='center')
p.image("examples/graphics/climacons/rain.png")
p.qr("Dies ist ein Test", size=8)
p.set()

p.barcode('1324354657687', 'EAN13', width=3)
p.barcode('123456', 'CODE39', width=3)

p.block_text("Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet. Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet.", font='a', columns=None)

p.cut()

redis-server on ubuntu 18.04

After installing redis on my machine I received the following error message:

redis-server.service: Can’t open PID file /var/run/redis/redis-server.pid (yet?) after start: No such file or directory

This message comes because redis refuses to start with disabled ipv6. To get it running you have to remove “::1” from “bind 127.0.0.1 ::1” in /etc/redis/redis.conf. Then redis starts as expected.

Add charles certificate to JVM

This is an example how to do that on a Mac:

sudo keytool -import -noprompt -alias charles-$(date +%Y%m%d%H%M%S) -file "Downloads/charles-ssl-proxying-certificate.pem" -keystore "/Library/Java/JavaVirtualMachines/jdk-10.0.2.jdk/Contents/Home/lib/security/cacerts" -storepass changeit

 

Add charles ssl proxy certificates to JDK on a mac

First you need to run charles and enable SSL proxying. The see which JDK is used by your application and add the certificate to the cacerts file:

curl -s http://ssl.charles/ --proxy 127.0.0.1:8888 > cert_file
sudo keytool -import -noprompt -alias charles-$(date +%Y%m%d%H%M%S) \
  -file cert_file \
  -keystore /Library/Java/JavaVirtualMachines/jdk-10.0.2.jdk/Contents/Home/lib/security/cacerts \
  -storepass changeit
rm cert_file

 

Access Ubuntu 18.04 via VNC from Mac

Ubuntu

First prepare the ubuntu machine by installing vino:

sudo apt install vino

Then hit windows button and look for sharing. Configure the system to allow remote connections with given password.

You also need to disable encryption with:

gsettings set org.gnome.Vino require-encryption false

MAC

Then you can access the machine from your Mac with Screen Sharing app with the url

vnc://<IP>:5900

 

Add network bridge with ubuntu 18.04

To create a network bridge with netplan you have to create a file

network:
  version: 2
  ethernets:
     enp6s0:
        dhcp4: true
  bridges:
     br0:
       interfaces: [enp6s0]
       dhcp4: true
       optional: false
       macaddress: <some mac>

Make sure to place a mac address in and replace the interface name enp6s0 with yours.

Then run sudo netplan apply.

The machine gets a new IP from dhcp so make sure you have it configured in your dhcp before or have a local console 😉