My Tech Notes

Java: check if a String contains only ASCII

2024-07-29T17:29:00.000-07:00

import java.nio.charset.Charset;

public boolean isAscii(String v) {
    Charset.forName("US-ASCII").newEncoder().canEncode(v);
}

Eclipse: Disable auto escaping when pasting

2024-06-11T22:21:00.000-07:00

In the preferences menu deselect: Java > Editor > Typing > Escape text when pasting into a string literal
Disable smart insert mode: Edit > Smart Insert Mode [Ctrl+Shift+Insert]

Shell scripts to count files and sum up file sizes

2024-06-11T21:37:00.000-07:00

Fix Windows 10 Update KB5034441 Error 0x80070643

2024-03-23T15:54:00.000-07:00

The reason KB5034441 failed to install with error 0x80070643 is that there is not sufficient space in WinRE recovery partition. The solution is:

Manually resize your WinRE recovery partition by 250 MB

Open a Command Prompt window (cmd) as Administrator.
Check WindowsRE status:
```
reagentc /info
```
If the WinRE is installed, there should be a “Windows RE location” with a path to the WinRE directory. An example is, “Windows RE location: [file://%3f/GLOBALROOT/device/harddisk0/partition4/Recovery/WindowsRE]\\?\GLOBALROOT\device\harddisk0\partition4\Recovery\WindowsRE.” Here, the number after “harddisk” and “partition” is the index of the disk and partition WinRE is on.
Disable the WindowsRE:
```
reagentc /disable
```
Shrink the OS partition and prepare the disk for a new recovery partition.
- Run
```
diskpart
```
- Run
```
list disk
```
- Select the OS disk (This should be the same disk index as WinRE.), run
```
sel disk OS_DISK_INDEX
```
  e.g.
```
sel disk 0
```
  if disk 0 is the OS disk.
- Find the OS Primary partition, run
```
list part
```
- Select the OS Primary partition, run
```
sel part OS_PARTITION_INDEX
```
- Shrink the OS Primary partition by 250MB, run
```
shrink desired=250 minimum=250
```
Delete the WinRE recovery partition
- In diskpart, select WinRE partition, run
```
sel part WinRE_PARTITION_INDEX
```
- Delete the WinRE partition, run
```
delete partition override
```
Create a new WinRE recovery partition.
- First, check if the disk partition style is a GUID Partition Table (GPT) or a Master Boot Record (MBR). To do that, run
```
list disk
```
  . Check if there is an asterisk character (*) in the “Gpt” column. If there is an asterisk character (*), then the drive is GPT. Otherwise, the drive is MBR.
- If your disk is GPT, run
```
create partition primary id=de94bba4-06d1-4d40-a16a-bfd50179d6ac
```
  followed by the command
```
gpt attributes =0x8000000000000001
```
- If your disk is MBR, run
```
create partition primary id=27
```
Format the new WinRE recovery partition, run
```
format quick fs=ntfs label="Windows RE tools"
```
To confirm that the WinRE partition is created, run
```
list vol
```
Exit from diskpart, run
```
exit
```
Re-enable WinRE, run
```
reagentc /enable
```
To confirm where WinRE is installed, run
```
reagentc /info
```

Now you should be able to install KB5034441 via Windows Update

Compress sparse files preserving their holes

2023-04-26T20:01:00.003-07:00

use -S option for tar

tar -Sczvf sparse_file.tar.gz sparse_file

Find FIFO (named pipe) in Linux

2023-04-26T16:05:00.002-07:00

 find ./ -type p

Find sparse files in Linux

2023-04-26T16:04:00.002-07:00

find ./ -type f -printf "%S\t%p\n" | awk '$1 < 1.0 {print}'

find ./ -type f -printf "%S\t%p\n" | awk '$1 < 1.0 {print $2}'

To find and remove the sparse files:

find ./ -type f -printf "%S\t%p\n" | awk '$1 < 1.0 {print $2}' | xargs rm -f

To find and compress the sparse files:

find ./ -type f -printf "%S\t%p\n" | awk '$1 < 1.0 {print $2}' | xargs -I {} sh -c "tar -Sczvf {}.tar.gz {}; rm -f {}"

Excel custom formatting cells for file sizes (GB and TB)

2023-03-21T19:03:00.006-07:00


[<1000000]0.00," KB";[<1000000000]0.00,," MB";0.00,,," GB"
[<1000000000]0.00,," MB";[<1000000000000]0.0,,," GB";0.0,,,," TB"

SSH public key authentication rejected with debug message: no mutual signature algorithm

2023-03-14T23:14:00.001-07:00

ssh user@remote-server -vvvv

debug1: no mutual signature algorithm

Cause

The RSA SHA-1 hash algorithm is being quickly deprecated across operating systems and SSH clients because of various security vulnerabilities, with many of these technologies now outright denying the use of this algorithm.

Solution

Generate SSH key using ED25519 algorithm:

ssh-keygen -t ed25519

Install RSAT Active Directory Administrative Center on Windows 10 (22H2)

2023-03-07T17:56:00.004-08:00

Run PowerShell as Administrator and paste the commands below:


$currentWU = Get-ItemProperty -Path "HKLM:\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\AU" -Name "UseWUServer" | select -ExpandProperty UseWUServer
Set-ItemProperty -Path "HKLM:\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\AU" -Name "UseWUServer" -Value 0
Restart-Service wuauserv
Get-WindowsCapability -Name Rsat.ActiveDirectory.DS-LDS.Tools -Online | Add-WindowsCapability –Online
Set-ItemProperty -Path "HKLM:\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\AU" -Name "UseWUServer" -Value $currentWU
Restart-Service wuauserv

Neovim: option list

2023-02-27T02:38:00.001-08:00

Quick Reference: Neovim options

Java: remove unsafe html tags

2023-02-23T20:27:00.002-08:00


public class HtmlTagRemover {
    public static String removeUnsafeTags(String html) {
        // Define the regular expression pattern to match unsafe tags
        String unsafeTagsPattern = "<(script|iframe|object|embed)[^>]*>.*?</\\1>";

        // Remove the unsafe tags from the HTML string
        String safeHtml = html.replaceAll(unsafeTagsPattern, "");

        return safeHtml;
    }

    public static void main(String[] args) {
        String html = "<b>Safe HTML</b><script>alert('XSS')</script>";
        String safeHtml = removeUnsafeTags(html);
        System.out.println(safeHtml);
    }
}

Install pre-requisites for flake8 (python language server) on Linux

2023-02-23T20:21:00.004-08:00

Install pip:
```
sudo apt install python3-pip
```
Check python version:
```
python3 --version
```
```
Python 3.10.6
```
Install virtualenv:
```
sudo apt install python3.10-virtualenv
```

My zsh prompt setup

2023-02-23T20:13:00.006-08:00

Add following line to ~/.zshrc:

PROMPT='%F{red}%*%f %F{blue}%1~%f %# '

More details about ZSH prompt: https://zsh.sourceforge.io/Doc/Release/Prompt-Expansion.html

Setup Neovim and LazyVim

2023-02-22T03:47:00.006-08:00

I. Install Neovim

Download nightly build from https://github.com/neovim/neovim/releases/tag/nightly
Alternatively, build from source: https://github.com/neovim/neovim/wiki/Building-Neovim

II. Install LazyVim

Follow the instructions to install LazyVim: https://www.lazyvim.org/installation

Install fd, ripgrep, fzf, lazygit:

Mac OS:
```
brew install fd ripgrep fzf lazygit
```
Linux:
```
apt install fd-find ripgrep fzf lazygit
```

III. Configuration

Install toggleterm.nvim. Create file: ~/.config/nvim/lua/plugins/toggleterm.lua:

-- ~/.config/nvim/lua/plugins/toggleterm.lua
return {
  {
    "akinsho/toggleterm.nvim",
    tag = "2.4.0",
    keys = {
      { "<leader>th", "<cmd>ToggleTerm size=15 direction=horizontal<cr>", desc = "Open a horizontal terminal" },
      { "<leader>tt", "<cmd>ToggleTerm<cr>", desc = "Toggle terminal" },
      { "<F7>", "<cmd>ToggleTerm<cr>", desc = "Toggle terminal" },
      { "<F7>", "<cmd>ToggleTerm<cr>", mode= "t", desc = "Toggle terminal" },
    },
    opts = {
      --[[ things you want to change go here]]
    },
  },
}

Set options in ~/.config/nvim/lua/config/options.lua:

-- ~/.config/nvim/lua/config/options.lua
vim.opt.relativenumber = false -- Relative line numbers
vim.opt.shiftwidth = 4 -- Size of an indent
vim.opt.tabstop = 4 -- Number of spaces tabs count for

Install nightfox colorscheme. Create file: ~/.config/nvim/lua/plugins/colorscheme.lua:

-- ~/.config/nvim/lua/plugins/colorscheme.lua
return {
  -- add nightfox colorscheme
  { "EdenEast/nightfox.nvim" },

  -- Configure LazyVim to load nightfox
  {
    "LazyVim/LazyVim",
    opts = {
      colorscheme = "carbonfox",
    },
  }
}

My favourite VIM/Neovim colorschemes

2023-02-21T02:02:00.002-08:00

Mac OS: fix duplicated Open With entries

2023-02-17T01:34:00.000-08:00

/System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/LaunchServices.framework/Versions/A/Support/lsregister -kill -r -domain local -domain user;killall Finder;echo "Open With has been rebuilt, Finder will relaunch"

Compile Neovide from source on Mac OS

2023-02-16T22:44:00.004-08:00

Install the latest version of Rust.
Install CMake. Using homebrew:
```
brew install cmake
```

Check out the source code:

git clone https://github.com/neovide/neovide

Compile and install the binary: neovide into ~/.cargo/bin:
```
cd neovide
cargo install --path .
```
The resulting binary is to be found under ~/.cargo/bin.
In case you want a nice application bundle:
```
cargo install cargo-bundle
cargo bundle --release
```
Copy ./target/release/bundle/osx/neovide.app to ~/Applications and enjoy.

NeoVim: Clean Up Everything (Config, Plugins, Cache ...)

2023-02-16T04:07:00.008-08:00

# linux/macos (unix)
rm -rf ~/.config/nvim
rm -rf ~/.local/share/nvim
rm -rf ~/.local/state/nvim
rm -rf ~/.cache/nvim


# windows
rd -r ~\AppData\Local\nvim
rd -r ~\AppData\Local\nvim-data

Use GNU grep to count the length of substring between two words

2023-02-15T13:58:00.003-08:00

Note: the command below requires GNU grep, it is available on Linux by default. On Mac OS, you need to install it manually using

brew install grep

and command is called ggrep instead of grep.

Get the substring between two words

echo "<person><name>abc</name></person>" | grep -o -P '(?<=<name>).*(?=</name>)'

Output should be:

abc

Count the length of substring

echo "<person><name>abc</name></person>" | grep -o -P '(?<=<name>).*(?=</name>)' | wc -c

Output should be:

Count substring lengths for each line

cat multi-lines.txt | while read line; do echo $line | grep -o -P '(?<=<name>).*(?=</name>)' | wc -c; done

Use grep to count number of occurs of a specific element in a single line XML text

2023-02-15T13:44:00.000-08:00

For example, I can input.txt below, three lines of XML text, I want to count the number of id elements for each line:

<result><id>1</id><id>5</id><id>7</id></result>
<result><id>71</id></result>
<result><id>15</id><id>33</id></result>

I use grep -o:

cat input.txt | while read line; do echo $line | grep -o '<id>' | wc -l; done

The output should be:

3
1
2

Regular Expression Capture Groups

2023-02-08T14:05:00.004-08:00

Capture groups:


use regex::Regex;

let re = Regex::new(r"(\w+)").unwrap();
let text = "Hello world";

for cap in re.captures_iter(text) {
    println!("Match: {}", &cap[1]);
}

Named capture groups:


use regex::Regex;

let re = Regex::new(r"(?<word>\w+)").unwrap();
let text = "Hello world";

for cap in re.captures_iter(text) {
    println!("Match: {}", &cap["word"]);
}

Enable code syntax highlighting in blogger site using highlightjs

2023-02-02T23:03:00.006-08:00

Template -> Edit HTML

Insert the following inside <head> tag:

    
    <!-- BEGIN: Syntax Highlighting with highlight.js -->
    <link crossorigin='anonymous' href='https://cdnjs.cloudflare.com/ajax/libs/highlight.js/11.7.0/styles/agate.min.css' integrity='sha512-wI7oXtzNHj/bqfLA3P6x3XYbcwzsnIKaPLfjjX8ZAXhc65+kSI6sh8gLOOByOKImokAjHUQR0xAJQ/xZTzwuOA==' referrerpolicy='no-referrer' rel='stylesheet'/>
    <script crossorigin='anonymous' integrity='sha512-bgHRAiTjGrzHzLyKOnpFvaEpGzJet3z4tZnXGjpsCcqOnAH6VGUx9frc5bcIhKTVLEiCO6vEhNAgx5jtLUYrfA==' referrerpolicy='no-referrer' src='https://cdnjs.cloudflare.com/ajax/libs/highlight.js/11.7.0/highlight.min.js'/>
    <script>hljs.highlightAll();</script>
    <!-- END: Syntax Highlighting with highlight.js -->
    <!-- BEGIN: CSS for code in pre and code -->
    <style type='text/css'>
        pre {
            font-family: monospace;
            font-size: 1 em;
            background: #333;
            color: #33cc33;
            tab-size: 4;
            padding: 5px;
            border: 1px dotted grey;
            border-radius: 5px;
            line-height: 2.0;
            overflow-x: auto;
            white-space: pre-wrap;
        }

        code {
            white-space: pre-wrap;
            overflow-x: scroll;    
            font-family: monospace;
            font-size: 1em;
        }
    </style>
    <!-- END: CSS for code in pre and code -->

Click save icon to save the template

Use it in your blog post:

<pre><code class="language-html">...</code></pre>

Customize AstroNvim

2023-01-26T17:34:00.009-08:00

Enable user customisation

cp -r ~/.config/nvim/lua/user_example ~/.config/nvim/lua/user

Install new plugins

nvim ~/.config/nvim/lua/user/init.lua


  plugins = {
    init = { 
      -- You can also add new plugins here as well:
      -- Add plugins, the packer syntax without the "use"
      { "bryant-the-coder/astron.nvim" }, -- astron colorscheme
    },
  },

:PackerSync

Change colorscheme

nvim ~/.config/nvim/lua/user/init.lua

 -- Set colorscheme to use
 -- colorscheme = "default_theme",
 colorscheme = "astron",

Disable relativenumber option

nvim ~/.config/nvim/lua/user/init.lua

relativenumber = false,

Setup Neovim for Rust Development

2023-01-24T16:47:00.011-08:00

Install Neovim
Install AstroNvim
- After installed AstroNvim, you can customise it
Install rust LSP
In Neovim, execute command:
```
:LspInstall rust
```
Install rust language parser (tree-sitter)
In Neovim, execute command:
```
:TSInstall rust
```
Install lua language parser (tree-sitter)
In Neovim, execute command:
```
:TSInstall lua
```
This is useful for editting the Neovim config (lua) files (*.lua)

My Tech Notes

Java: check if a String contains only ASCII

Eclipse: Disable auto escaping when pasting

Shell scripts to count files and sum up file sizes

Fix Windows 10 Update KB5034441 Error 0x80070643

Manually resize your WinRE recovery partition by 250 MB

See also

Compress sparse files preserving their holes

Find FIFO (named pipe) in Linux

Find sparse files in Linux

Excel custom formatting cells for file sizes (GB and TB)

SSH public key authentication rejected with debug message: no mutual signature algorithm

Cause

Solution

See also

Install RSAT Active Directory Administrative Center on Windows 10 (22H2)

see also

Neovim: option list

see also

Java: remove unsafe html tags

Install pre-requisites for flake8 (python language server) on Linux

My zsh prompt setup

Setup Neovim and LazyVim

I. Install Neovim

II. Install LazyVim

III. Configuration

See also

My favourite VIM/Neovim colorschemes

See also

Mac OS: fix duplicated Open With entries

see also

Compile Neovide from source on Mac OS

See also

NeoVim: Clean Up Everything (Config, Plugins, Cache ...)

see also

Use GNU grep to count the length of substring between two words

Get the substring between two words

Count the length of substring

Count substring lengths for each line

see also

Use grep to count number of occurs of a specific element in a single line XML text

Regular Expression Capture Groups

Enable code syntax highlighting in blogger site using highlightjs

See also

Customize AstroNvim

Enable user customisation

Install new plugins

Change colorscheme

Disable relativenumber option

See also

Setup Neovim for Rust Development

See also