Ivan’s Solutions

Neo4j Websocket Connection Failure

2022-03-29T00:00:00+00:00

*from [GitHub: Windows Terminal Issue 5420][github-5420], [GitHub: Windows Terminal Issue 5256][github-5256]

Synopsis

Upon pressing Connect in the Neo4j web interface, the following message is displayed:

ServiceUnavailable: WebSocket connection failure. Due to security constraints in your web browser, the reason for the failure is not available to this Neo4j Driver. Please use your browsers development console to determine the root cause of the failure. Common reasons include the database being unavailable, using the wrong connection URL or temporary network problems. If you have enabled encryption, ensure your browser is configured to trust the certificate Neo4j is configured to use. WebSocket `readyState` is: 3

Multiple solutions are proposed by the Neo4j team and elsewhere usually involve manipulating configuration files. Solutions presented below have not been mentioned anywhere.

Possible Solutions

Bad cookies.
Try connecting to the database in the incognito mode, and if that works, clear the site for the domain.

Expired TLS certificate.
Neo4j has a separate directory for the the TLS certificates, and they have to be identical to the ones issued for the domain.
Unlike in previous versions, in Neo4j 4+ runs as a service, and its files and directories are decentralized.
Certificates to be updated are in /var/lib/neo4j/certificates
For letsencrypt, you can use the following script (replace YOUR-DOMAIN-NAME and inspect the paths for correctness):

 #!/usr/bin/env bash

 pkeysrc="/etc/letsencrypt/live/YOUR-DOMAIN-NAME/privkey.pem"
 certsrc="/etc/letsencrypt/live/YOUR-DOMAIN-NAME/fullchain.pem"
 pkeydst="/var/lib/neo4j/certificates/neo4j.key"
 certdst="/var/lib/neo4j/certificates/neo4j.cert"

 update() {
     echo "updating certificates..."
     cp $pkeysrc $pkeydst
     cp $certsrc $certdst
     systemctl restart neo4j
 }

 diff $pkeysrc $pkeydst 2>&1 > /dev/null || update

Additional Considerations

Access to cypher shell may be hampered as well. A default cypher-shell command may yield this:

Connection to the database terminated. Please ensure that your database is listening on the correct host and port and that you have compatible encryption settings both on Neo4j server and driver. Note that the default encryption setting has changed in Neo4j 4.0.

This is because Neo4j 4+ handles the encryption information differently (and more strictly) compared to the previous versions. To launch cypher shell for an Neo4j app running with encryption, one has to specify the URI scheme, the application address, and the correct bolt port.
There are two possible options:

The advertised address (secured with full certificate):
```
 cypher-shell -a neo4j+s//:YOUR-DOMAIN-NAME:7687
```
Localhost (secured with self-signed certificate):
```
 cypher-shell -a neo4j+ssc//:localhost:7687
```

How to Enable Call Recording in LineageOS

2022-02-18T00:00:00+00:00

*from XDA developers and Stackexchange

Environment

ADB
LineageOS 18.1
Windows 11
Easy APK Tool

Instructions

Connect the phone to a PC with a USB cable.
Navigate to a directory with adb.exe
Right click, PowerShell -> Open here

In the shell, execute:

 cd /system/product/priv-app/Dialer
 cp Dialer.apk /storage/self/primary/Documents

On your phone, go to Documents folder, and move the Dialer.apk to your PC via email or IM.
Decompile Dialer.apk using Easy APK Tool.
Navigate to the corresponding decompiled Dialer folder, and there into subdirectory res/xml
Open call_record_states.xml in a text editor and replace all false strings with true
In Dialer folder, navigate into the subdirectory res/values
Open styles.xml

Line #25 is a duplicate, delete it:

<item name="android:textColorPrimary">@color/dialer_primary_text_color</item>

Using Easy APK Tool, recompile the Dialer folder into a new Dialer.apk
Upload the new Dialer.apk to the Documents folder on your phone.
Reconnect the phone to a PC.
In the same PowerShell, run:
```
adb root
adb remount
adb shell
```

In the shell, execute:

mv /storage/self/primary/Documents/Dialer.apk /system/product/priv-app/Dialer
cd /system/product/priv-app/Dialer
chmod 644 Dialer.apk
exit

Reboot:
```
adb reboot
```
When you start a call, a new button with a Record symbol will appear in the Dialer UI.

WSL2: Temporary Failure in Name Resolution

2021-11-22T00:00:00+00:00

*from GitHub: Windows Terminal Issue 5420, GitHub: Windows Terminal Issue 5256

In WSL2, run:

# remove existing resolv.conf symlink that is pointing to a wrong nameserver
sudo rm /etc/resolv.conf
# create a new resolv.conf with a correct nameserver
sudo bash -c 'echo "nameserver 1.1.1.1" > /etc/resolv.conf'
# stop wsl from regenerating resolv.conf symlink
sudo bash -c 'printf "[network]\ngenerateResolvConf = false" > /etc/wsl.conf'
# make current resolv.conf immutable so that wsl does not delete it
sudo chattr +i /etc/resolv.conf

In powershell, run

wsl --shutdown
wsl

Windows Terminal: Run PowerShell as Administrator

2021-07-12T00:00:00+00:00

*from GitHub: Windows Terminal Issue 691, GitHub: gerardog/gsudo

Currently, Windows Terminal does not support running individual tabs as Administrator.
There is an elegant workaround employing a third-party application, gsudo.

Start PowerShell as Administrator.
Run:
```
 choco install gsudo -y 
```
Note: you don’t need chocolatey; refer to the gsudo source.
Open Windows Terminal -> Settings -> Add new
Under Command line add this:
```
 pwsh.exe -Command "gsudo pwsh"
```
Note: pwsh is for PowerShell 7 (if you have it). This works equally well for the default PowerShell: just replace pwsh with powershell.
Change the tab icon to distinguish it from the non-elevated version.
Here’s a red one.

Install/Configure VirtualEnvWrapper

2020-10-30T00:00:00+00:00

*from readthedocs, Stack Overflow (1), Stack Overflow (2)

# 1. Install
pip3 install virtualenvwrapper

# 2. Create a directory for your environments
$ mkdir ~/py-envs/

# 3. Add a path to where virtual environments will be stored to your profile
$ echo "export WORKON_HOME=~/py-envs" >> ~/.profile

# 4. Add a path to the correct python symlink or executable to your profile
$ echo "export VIRTUALENVWRAPPER_PYTHON=/usr/bin/python3" >> ~/.profile

# 5. You need to run this shell script at the start of every session, 
#    so add it to your profile
$ echo "source /usr/local/bin/virtualenvwrapper.sh" >> ~/.profile

# 6. Source
$ source ~/.profile

# 7. Commands are available now, e.g., to make and load an environment:
$ mkvirtualenv env1
$ workon env1
(env1)$ 

Change Location of WSL2 Container

2020-10-26T00:00:00+00:00

*from dev.to

WSL2 container is located on the C:\ drive by default. This can be inconvenient, as it can grow to a substantial size.
The size of the container becomes a particular concern considering that to reap WSL2’s performance benefits, one should store the data directly in the container.
While there are guides on how to import a new distribution via PowerShell, there’s little information on how to simply move an existing container that is connected to an existing Linux WSL2 installation (e.g. Ubuntu).

Open PowerShell:
```
 $ wsl --list --verbose
```
Note the name of the distribution of interest: ```console NAME STATE VERSION
- Ubuntu Running 2 ```
Shut down all WSL containers:
```
 $ wsl --shutdown
```
Open the Windows Registry Editor and navigate to:
```
 HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Lxss\
```
There, you will see the same number of keys as you have WSL distributions with random names, e.g. {c5ce672c-4a91-40aa-b32e-6a149ea92380}.
Inspect the contents of those keys, and specifically look for the value DistributionName.
Naturally, you’re looking for the key with the DistributionName value equal to the name of your distribution of interest.

Once located, Open the BasePath value. It’ll look something like that:

 C:\Users\IvanGrishagin\AppData\Local\Packages\CanonicalGroupLimited.UbuntuonWindows_79rhkp1fndgsc\LocalState

Follow the path, where you’ll find a file aptly named ext4.vhdx.
Copy this file to your new destination, e.g. D:\VirtualMachines\WSL2\Ubuntu.
Replace the path in the BasePath value with the new one (e.g. D:\VirtualMachines\WSL2\Ubuntu).
All done!

Setup R on Ubuntu

2018-10-29T00:00:00+00:00

*from Michael Rutter, Stack Overflow, and (of course) trial and error

Installing and setting up R on Ubuntu can be a frustrating experience due to multiple system dependencies.

Install R from a Personal Package Archive by Michael Rutter

Check for the current version here before the installation.

$ sudo add-apt-repository ppa:marutter/rrutter3.5
$ sudo apt-get update

Install Key Package Dependencies

In Windows, external R package dependencies (except Java) are installed automatically, and users are frequently unaware what is happening behind the scenes.
In a linux environment, the same dependencies require explicit installation via the linux package manager.

Install Java
```
$ sudo apt-get install default-jre
```

Install Curl

$ sudo apt-get install libcurl4-openssl-dev

In the future, check for the current curl version:

$ apt-cache search libcurl

Install OpenSSL
```
$ sudo apt-get install libssl-dev
```
Install LibXML
```
$ sudo apt-get install libxml2-dev
```

How to Setup Environment for RSelenium on Windows 10

2017-11-11T00:00:00+00:00

from RSelenium vignette, RPubs, and Docker GitHub

RSelenium moved to using Docker, which allows to standardize package behavior across operating systems, and therefore remove all concomitant issues.

Download and Install

Docker, an environment to run Selenium server.
TightVNC, a viewer to observe the result of RSelenium navigation commands.

Setup Docker to work with Selenium

Enable hardware virtualization. It is sufficient to enable it in BIOS, and subsequent steps are unnecessary. If you don’t have it enabled, Docker will throw the following error:
```
This computer doesn't have VT-X/AMD-v enabled. Enabling it in the BIOS is mandatory.
```
Save this json file as latest.json into /Users/{user}/.docker/machine/cache/.
Upon starting, Docker will download boot2docker.iso.
Without it, you most likely will see the following error upon Docker launch:
```
No default Boot2Docker ISO found locally, downloading the latest release...
```
Start Docker Quickstart Terminal. You should see a console prompt similar to this one:

In Docker Terminal run the following commands:

$ docker pull selenium/standalone-chrome
$ docker run -d -p 4445:4444 selenium/standalone-chrome

A full list of Selenium Docker images is available here.

Alternatively, for debug mode (to enable viewing results of RSelenium navigation) use:
```
$ docker pull selenium/standalone-chrome-debug
$ docker run -d -p 5901:5900 -p 4445:4444 selenium/standalone-chrome-debug
```
Then start the TightVNC.
In the prompt, enter 192.168.99.100:5901 as Remote Host: and click Connect.
In the next window enter secret as Password:.
The result of all RSelenium navigation commands can be seen in this window.

Connect R Session to Selenium Server

In R, create a remoteDriver object, and navigate to a desired url:

#load RSelenium package
require(RSelenium)
#point to the remote server
remDr<- 
       remoteDriver(remoteServerAddr = "192.168.99.100" 
                    , port = 4445L 
                    , browserName = "chrome"
					)
#navigate to url
remDr$open()
remDr$navigate("https://www.google.com/")

How to Install Lisp on Windows 10

2017-01-26T00:00:00+00:00

from Jonathan Fischer and YouTube

Download

Common LISP.
Emacs – editor / “IDE”.
Quicklisp – key LISP library that allows to download and maintain other libraries with ease.

Install

Install Emacs.
- Unpack contents of Emacs archive.
- Add Emacs directory (e.g. C:\ntemacs24\bin) to your PATH system variable.
Create HOME directory.
This is necessary to avoid problems with home directory recognition by lisp.
- Create the C:\HOME directory.
- Add a new system variable with Name HOME and Value C:\HOME.
Install CLISP.
- Create an easy-to-reach, easy-to-use directory. I use C:\lisp.
- Install CLISP in that directory.
  NOTE: the latest version at the time of writing is 2.49, but I’m having trouble getting it to load SLIME properly (see below), so version 2.48 it is. (file clisp-2.48-win32-mingw-big.exe).
- IMPORTANT:
  Installer of the version 2.48 is faulty.
  To fix this problem, copy svm.dll out of clisp-2.48/libsvm directory into clisp-2.48/full.

Install quicklisp.

Place quicklisp.lisp into C:\lisp
Run CLISP and execute the following:

(load "C:/lisp/quicklisp.lisp")
(quicklisp-quickstart:install :path "C:/lisp/quicklisp/")
(ql:add-to-init-file)

Install SLIME – Superior Lisp Interaction Mode for Emacs, an Emacs extension to make lisp development seamless.
In the CLISP console execute:
```
(ql:quickload "quicklisp-slime-helper")
```
Configure Emacs.
- Launch Emacs.
- Type Ctrl-x, then Ctrl-f.
- Enter ~/.emacs in the prompt at the bottom of the window.
- Add the following lines to the file:
```
(setq inferior-lisp-program "clisp.exe")
(load "C:/lisp/quicklisp/slime-helper.el")
```
- Type Ctrl-x, then Ctrl-s to save the file.

Windows 10 Ubuntu Bash Tips

2017-01-25T00:00:00+00:00

Fixing Color Scheme

from A Medium Corporation and bash:tip_colors_and_formatting

The goal is to replace dark blue color (unreadable on black background) with light magenta in Ubuntu bash console on Windows 10.

Open interactive shell script.
```
$ nano ~/.bashrc
```

At the end of the document add the following lines:

#fix color scheme 
LS_COLORS='rs=0:di=1;35:ln=01;36:mh=00:pi=40;33:so=01;35:do=01;35:bd=40;33;01:cd=40;33;01:or=40;31;01:su=37;41:sg=30;43:ca=30;41:tw=30;42:ow=34;42:st=37;44:ex=01;32:*.tar=01;31:*.tgz=01;31:*.arj=01;31:*.taz=01;31:*.lzh=01;31:*.lzma=01;31:*.tlz=01;31:*.txz=01;31:*.zip=01;31:*.z=01;31:*.Z=01;31:*.dz=01;31:*.gz=01;31:*.lz=01;31:*.xz=01;31:*.bz2=01;31:*.bz=01;31:*.tbz=01;31:*.tbz2=01;31:*.tz=01;31:*.deb=01;31:*.rpm=01;31:*.jar=01;31:*.war=01;31:*.ear=01;31:*.sar=01;31:*.rar=01;31:*.ace=01;31:*.zoo=01;31:*.cpio=01;31:*.7z=01;31:*.rz=01;31:*.jpg=01;35:*.jpeg=01;35:*.gif=01;35:*.bmp=01;35:*.pbm=01;35:*.pgm=01;35:*.ppm=01;35:*.tga=01;35:*.xbm=01;35:*.xpm=01;35:*.tif=01;35:*.tiff=01;35:*.png=01;35:*.svg=01;35:*.svgz=01;35:*.mng=01;35:*.pcx=01;35:*.mov=01;35:*.mpg=01;35:*.mpeg=01;35:*.m2v=01;35:*.mkv=01;35:*.webm=01;35:*.ogm=01;35:*.mp4=01;35:*.m4v=01;35:*.mp4v=01;35:*.vob=01;35:*.qt=01;35:*.nuv=01;35:*.wmv=01;35:*.asf=01;35:*.rm=01;35:*.rmvb=01;35:*.flc=01;35:*.avi=01;35:*.fli=01;35:*.flv=01;35:*.gl=01;35:*.dl=01;35:*.xcf=01;35:*.xwd=01;35:*.yuv=01;35:*.cgm=01;35:*.emf=01;35:*.axv=01;35:*.anx=01;35:*.ogv=01;35:*.ogx=01;35:*.aac=00;36:*.au=00;36:*.flac=00;36:*.mid=00;36:*.midi=00;36:*.mka=00;36:*.mp3=00;36:*.mpc=00;36:*.ogg=00;36:*.ra=00;36:*.wav=00;36:*.axa=00;36:*.oga=00;36:*.spx=00;36:*.xspf=00;36:';
export LS_COLORS
   
#change prompt after @ color from white (default) to light magenta
PS1='\[\e[37;1m\]\u@\[\e[35m\]\W\[\e[0m\]\$ '

Save changes and close nano by pressing Ctrl+X, followed by Y and Enter.