Rust 实战练习 - 2. OS，IO，Platform(注册表，/etc)

目标：

• 检测OS类型和基础信息
• File 和 IO 模块
• /etc或者注册表

OS related

use std::env;

fn main() {
    println!("OS module is not for check OS!\r\n");
    println!("Use ENV to detect OS info:");
    println!("OS: {}", env::consts::OS);
    println!("ARCH: {}", env::consts::ARCH);
    println!("FAMILY: {}", env::consts::FAMILY);
    println!("DLL_EXTENSION: {}", env::consts::DLL_EXTENSION);
    println!("EXE_EXTENSION: {}", env::consts::EXE_EXTENSION);

    if cfg!(windows) {
        println!("windows os!");
    }else if cfg!(unix) { 
        println!("unix os!")
    }else {
        println!("unknown os!")
    }

    println!("If need more info, need third part package: sysinfo");

}

io, file

use std::fs::File;
use std::io::{BufWriter, Read, Seek, SeekFrom, Write};

fn main() {
    {
        println!("Read Cargo.toml content!\r\n");
        let mut f = File::open("Cargo.toml").unwrap();
        let mut buf = [0u8; 1024];
        _ = f.seek(SeekFrom::Start(0));
        let n = f.read(&mut buf).unwrap();
        println!(
            "read {} byte, content: {}",
            n,
            String::from_utf8_lossy(&buf[..n])
        );
        _ = f.flush(); // 不用关闭，因为f超出作用域会自动Drop关闭
    }
    {
        // write
        println!("Create is write-only mode.\r\n");
        let f = File::create("fs.tmp").unwrap();
        let mut w = BufWriter::new(f);
        _ = w.write("abc hello 历史不会忘记你！".as_bytes());
        w.flush().unwrap();
    }
    {
        // Option
        println!("open is read-only mode, but option can change it.\r\n");
        let mut f = File::options().append(true).open("fs.tmp").unwrap();
        _ = f.write("xxxxxxxxxxxxx".as_bytes());
        _ = f.flush();
    }
    {
        // dev info
        let mut f = File::open("/proc/version").unwrap();
        let mut strbuf = String::new();
        _ = f.read_to_string(&mut strbuf);
        println!("{}", strbuf);
    }
}

etc 或 注册表

• Windows 下使用注册表，需要使用第三方库读写
• Linux下使用/etc/xxx/yyy, 使用File直接读写。Linux没有注册表的设计，但是gnome环境有 类似注册表的功能 gsetting. https://blog.csdn.net/tongyi04/article/details/127672241