Update rust, linux date and arch maintenance notes

Author: Yutsuten

notes/language/rust/cargo.md

@@ -21,16 +21,29 @@ cargo OPTIONS COMMAND
 | `test`   | Run the tests.                                    |
 | `update` | Update dependencies in the `Cargo.lock` file.     |
 
+Creating new rust project:
+
 ```shell
 cargo new myproject
-cd myproject
+```
+
+Add new dependency and feature:
+
+```shell
 cargo add iced
-# Create your script...
+cargo add bevy -F wayland
+```
+
+Build and run for development:
+
+```shell
 cargo run
 ```
 
-More details on `cargo update` and `Cargo.toml`
+:::tip
+More details on how `cargo update` and `Cargo.toml` works
 [here](https://doc.rust-lang.org/cargo/reference/specifying-dependencies.html).
+:::
 
 ### Release builds
 

notes/language/rust/crates/std.md

@@ -73,6 +73,7 @@ is useful to write lines to the file
 ```rust
 use std::fs;
 use std::io::prelude::*;
+use std::io::BufReader;
 
 let path = "config";
 

notes/tool/linux/arch/maintenance.md

@@ -3,6 +3,24 @@ title: Maintenance
 ref: https://wiki.archlinux.org/title/System_maintenance
 ---
 
+## Downgrade package
+
+[Arch Wiki reference](https://wiki.archlinux.org/title/Downgrading_packages)
+
+Check the latest updates in `/var/log/pacman.log`.
+To downgrade a package, run (example of `svt-av1`):
+
+```shell
+sudo pacman -U file:///var/cache/pacman/pkg/svt-av1-2.2.1-1-x86_64.pkg.tar.zst
+```
+
+Then to prevent upgrade of that package,
+edit `/etc/pacman.conf`:
+
+```txt
+IgnorePkg = svt-av1
+```
+
 ## System cleanup
 
 Every week, delete all cached versions of installed and uninstalled packages,

notes/tool/linux/package/date.md

@@ -4,9 +4,32 @@ title: Date
 
 ## Usage
 
+```shell
+date OPTIONS FORMAT
+```
+
+| Option | Description |
+| -- | -- |
+| `-d` `--date` | Use specified date instead of now. |
+
+## Examples
+
+Get formatted current time:
+
 ```shell
 date                       # Wed 20 May 2020 01:17:13 PM JST
 date '+%Y-%m-%d %H:%M:%S'  # 2020-05-20 13:18:19
+```
+
+Specify date relative to now:
+
+```shell
 date -d '+1 year'
 date -d '1 year ago'
 ```
+
+Specify date using a timestamp:
+
+```shell
+date -d @1735976522
+```