Ubuntu apt-get update with NO_PUBKEY error

 In Ubuntu, I'd encountered the following error when doing a apt-get update:

The following signatures couldn't be verified because the public key is not available: NO_PUBKEY F7E06F06199EF2F2

This key belongs to the repository https://qgis.org/ubuntu. To add the key, I did the following:

sudo apt-key adv --recv-keys --keyserver hkp://keyserver.ubuntu.com:80 F7E06F06199EF2F2

By default, the command above will called gpg which uses port 11371. I had to force command   to use port 80 instead. Also, please also pay attention that the protocol is called "hkp://"

Ref: https://askubuntu.com/questions/1119727/gpg-keyserver-receive-failed-connection-timed-out

Stop / hide up pcieport error in Ubuntu / Linux

 Number of ways  to try in grub:

• pci=nomsi
• pci=noaer
• pcie_aspm=off

Actual steps:

1. sudo vi /etc/default/grub
2. Edit line:
   GRUB_CMDLINE_LINUX_DEFAULT="quiet splash pci=noaer"
3. sudo update-grub
4. Reboot machine

Restart / Reboot Linux

To restart Linux anytime: Hold Alt-SysRq (i.e. PrtSc) and type R E I S U B

Reference:

http://blog.kember.net/articles/reisub-the-gentle-linux-restart/

Console log freezes / hangs in Eclipse

Sometimes your Eclipse console log becomes very jerky, freezes or even hang up.

It's very likely that your console log got something which is very long without word warp. It can even causes Windows itself becomes freezing too!

So make your console "Word wrap". Or set a width limit on the console in Eclipse preference. The problem will be solved.

SQL Developer installation in Windows 10

 Quick suggestion for getting the SQL Developer to work in Windows 10:

1. Get the SQL Developer (with JRE) edition. I got bad experience when getting SQL Developer to work with my own JDK 1.8 installation in Windows 10. No matter where I copy the MSVCR100.DLL (It always said JAVA_HOME\jre\bin\msvcr100.dll cannot be launched, crazy). So, just get the "with JRE" version.
   
   
2. The font size are crazily small on a high DPI screen. So get a larger font, right-click on the "sqldeveloper.exe", choose "Compatibility > Change high DPI settings > High DPI scaling override > System (Enhanced)"
   (Reference: https://christian-gohmann.de/2018/10/25/running-sql-developer-on-high-dpi-screens/)

Command line to stop Windows 10 updates

To stop Windows 10 updates:

> net stop wuauserv

> net stop bits

> net stop dosvc

Resume it:

> net start wuauserv

> net start bits

> net start dosvc

Ref: https://lifehacker.com/pause-windows-10-updates-easily-from-the-command-line-1786614642

Sign and verify your file using SSL / OpenSSL

I want to learn know to sign and verify my file using SSL / OpenSSL. And I'd found Enrico Zimuel has did a very nice illustration on this issue:

https://www.zimuel.it/blog/sign-and-verify-a-file-using-openssl

Add git information to your bash prompt

To show git information in your bash prompt, add the following function in your ~/.bashrc

function git-shell() {
  export GIT_PS1_SHOWDIRTYSTATE=1
  export PS1='\[\033[01;33m\] (git) \[\033[01;34m\]\w$(__git_ps1 " \[\033[01;32m\](%s)")\[\033[00m\]\n\$ '
}

Then, in your bash, run "git-shell" and you will get a nice git prompt:

 (git) /path_to_your_git_project (master *)
$ 

curl returns "ssl_choose_client_version:unsupported protocol" error in Ubuntu 20.x

If you encountered "ssl_choose_client_version:unsupported protocol" when using curl in Ubuntu 20:

    $ curl https://somehost/

 

curl: (35) error:1425F102:SSL routines:ssl_choose_client_version:unsupported protocol

It may because the "somehost" only accepts old protocol (e.g. TLS v1, etc.), but in Ubuntu 20.x, the OpenSSL assumes minimum = TLS v1.2 by default. 

If the "somehost" just cannot upgrade to TLS v1.2, you might consider fixing it with the following:

1) Modify /etc/ssl/openssl.cnf

Search for the line "oid_section = new_oids"

Add the following lines below it:

openssl_conf = default_conf

[default_conf]

ssl_conf = ssl_sect

[ssl_sect]

system_default = system_default_sect

[system_default_sect]

MinProtocol = TLSv1.1

CipherString = DEFAULT@SECLEVEL=1

2) curl "somehost" with the following parameters

$ curl --tlsv1 https://somehost

3) If the "somehost" just using a self-signed certificate

    $ curl -k --tlsv1 https://somehost

Reference:

https://my.oschina.net/u/4288355/blog/4268255

SQL Developer JavaFX problem

When running SQL Developer in Linux, you may encounter the "JavaFX" problem stating that the JavaFX libraries / components are not found. To solve this issue, you can consider the following solution:

1. Install SDKMAN
2. Use SDKMAN to install either "OpenJDK 11" or "Zulu JDK with FX"
• sdk install java 11.0.7-open

                OR

• sdk install java 8.0.252.fx-zulu
1. Check the SQL Developer "product.conf" file to make sure the correct JDK is used.
• ~/.sqldeveloper/<version>/product.conf
• SetJavaHome /path_to_java_home
2. If you just comment out the "SetJavaHome" variable, then the current JDK you use will be used with SQL Developer.

Enjoy!