Update some rust notes

Author: Yutsuten

notes/language/rust/crates/std.md

@@ -202,10 +202,32 @@ Other common methods:
 Using `keys().collect()` may be useful to `.sort()` and iterate the `HashMap` in the same order,
 because by default the order can change each run.
 
-## Process
+## External command
 
-Run external commands.
+Run external commands and get `stdout` as UTF8 `String`:
 
 ```rust
-process::Command::new("swaymsg").args(["output", "*", "bg", wallpaper.as_str(), "fill"]).output().unwrap();
+let output = process::Command::new("echo").args(["Hello World!"]).output().unwrap();
+let text = String::from_utf8(output.stdout);
+```
+
+To get `stdout` in real time, a buffer is needed ([Rust Cookbook](https://rust-lang-nursery.github.io/rust-cookbook/os/external.html#continuously-process-child-process-outputs)):
+
+```rust
+use std::process::{Command, Stdio};
+use std::io::{BufRead, BufReader};
+
+fn main() {
+    let stdout = Command::new("ffmpeg")
+        .args(ffmpeg_args)
+        .stdout(Stdio::piped())
+        .spawn()
+        .unwrap()
+        .stdout
+        .unwrap();
+    let reader = BufReader::new(stdout);
+    reader
+        .lines()
+        .for_each(|line| println!("{}", line.unwrap()));
+}
 ```

notes/language/rust/numbers.md

@@ -5,16 +5,26 @@ ref: https://forkful.ai/en/rust/numbers/rounding-numbers/
 
 ## Methods
 
-| Method | Description |
-| --- | --- |
-| `round` | Round to nearest whole number. |
-| `floor` | Largest integer less than or equal to number. |
-| `ceil` | Smallest integer greater than or equal to number. |
-| `trunc` | Integer part without fractional digits. |
+| Method  | Description                                       |
+| ------- | ------------------------------------------------- |
+| `round` | Round to nearest whole number.                    |
+| `floor` | Largest integer less than or equal to number.     |
+| `ceil`  | Smallest integer greater than or equal to number. |
+| `trunc` | Integer part without fractional digits.           |
 
 Example:
 
 ```rust
 let pi = 3.141592;
 let round_pi = pi.round();
 ```
+
+## Update reference
+
+If updating a number in a function that received it as `&mut`:
+
+```rust
+fn update_counter(&mut count) {
+    *count += 1;
+}
+```

notes/language/rust/string.md

@@ -13,7 +13,7 @@ const GLOBAL_STR: &'static str = "Available globally";
 let mystr = "Hello World";
 let string_type1 = String::from(mystr);
 let string_type2 = mystr.to_owned(); // `.to_string()` also ok
-let back_to_str = string_type1.to_str();
+let back_to_str = string_type1.as_str();
 let raw_string = r#"
     {
         "name": "John Doe",
@@ -40,6 +40,8 @@ let keyvalue_display = format!("{}={}", key, value);
 | `trim`             | Returns a string slice with leading and trailing whitespace removed (includes `\n`). |
 | `split`            | Splits a string slice by one or more characters.                                     |
 | `split_whitespace` | Splits a string slice by any amount of whitespace.                                   |
+| `clear`            | Truncates this `String`, removing all contents.                                      |
+| `push_str`         | Appends a given string slice onto the end of this `String`.                          |
 
 ### Split
 
@@ -87,3 +89,18 @@ match text.as_str() {
     _ => panic!("Expected true or false");
 }
 ```
+
+## Update without assign
+
+If updating a `String` in a function that received it as `&mut`,
+reassigning do not work.
+
+```rust
+fn update_string(&mut s) {
+    // Instead of:
+    // s = String::from("New string");
+    // Do:
+    s.clear();
+    s.push_str("New string");
+}
+```

notes/tool/anki.md

@@ -30,7 +30,7 @@ first create and activate a virtual environment:
 python -m venv --system-site-packages .venv
 ```
 
-The packages `pyqt6 pyqt6-webengine` will also be needed.
+The package `python-pyqt6-webengine` will also be needed.
 Prefer your system's package manager to install it.
 
 ```shell