如何在不进入Golang循环的情况下捕获按键

I've got a loop in which some things happen according to the state it runs in (manual/automatic/learning). I now want to be able to let the program switch between these states by pressing the accompanying letters on the keyboard ("m" for manual, "a" for automatic and "l" for learning).

So to do this I need to be able to catch a keypress during the loop and change the variable status accordingly. I now have the following, which can catch a keypress followed by an enter:

ch := make(chan string)
go func(ch chan string) {
    reader := bufio.NewReader(os.Stdin)
    for {
        s, _ := reader.ReadString('
')
        ch <- s
    }
}(ch)

for {
    select {
        case stdin, _ := <-ch:
            fmt.Println("Keys pressed:", stdin)
        default:
            fmt.Println("Working..")
    }
    time.Sleep(time.Second)
}

But the fact that I need to hit the enter button is not acceptable.

Does anybody know a non-blocking way to catch a keypress of a normal letter (not a SIGINT) without the need to hit enter afterwards?

Because you're using ReadString which expects whichever parameter you give it, in your case - the return key. According to the docs:

ReadString reads until the first occurrence of delim in the input, returning a string containing the data up to and including the delimiter.

This means that the method won't return until you hit the return key.

You can use the regular Read method instead, to read the characters you need. See also this Stackoverflow question for reference.

Ok, after reading about os.Stdin.Read() and finding this answer I created the following code:

package main

import (
    "fmt"
    "os"
    "time"
    "os/exec"
)

func main() {
    ch := make(chan string)
    go func(ch chan string) {
        // disable input buffering
        exec.Command("stty", "-F", "/dev/tty", "cbreak", "min", "1").Run()
        // do not display entered characters on the screen
        exec.Command("stty", "-F", "/dev/tty", "-echo").Run()
        var b []byte = make([]byte, 1)
        for {
            os.Stdin.Read(b)
            ch <- string(b)
        }
    }(ch)

    for {
        select {
            case stdin, _ := <-ch:
                fmt.Println("Keys pressed:", stdin)
            default:
                fmt.Println("Working..")
        }
        time.Sleep(time.Millisecond * 100)
    }
}

This works like a charm so I'm just posting for any future readers.

Regardless, I wish you a beautiful day!