function similar to getchar

Thanks goes to Paul Rademacher - this works (at least on Mac):

package main

import (
    "bytes"
    "fmt"

    "github.com/pkg/term"
)

func getch() []byte {
    t, _ := term.Open("/dev/tty")
    term.RawMode(t)
    bytes := make([]byte, 3)
    numRead, err := t.Read(bytes)
    t.Restore()
    t.Close()
    if err != nil {
        return nil
    }
    return bytes[0:numRead]
}

func main() {
    for {
        c := getch()
        switch {
        case bytes.Equal(c, []byte{3}):
            return
        case bytes.Equal(c, []byte{27, 91, 68}): // left
            fmt.Println("LEFT pressed")
        default:
            fmt.Println("Unknown pressed", c)
        }
    }
    return
}

C's getchar() example:

#include <stdio.h>
void main()
{
    char ch;
    ch = getchar();
    printf("Input Char Is :%c",ch);
}

Go equivalent:

package main

import (
    "bufio"
    "fmt"
    "os"
)

func main() {

    reader := bufio.NewReader(os.Stdin)
    input, _ := reader.ReadString('\n')

    fmt.Printf("Input Char Is : %v", string([]byte(input)[0]))

    // fmt.Printf("You entered: %v", []byte(input))
}

The last commented line just shows that when you press tab the first element is U+0009 ('CHARACTER TABULATION').

However for your needs (detecting tab) C's getchar() is not suitable as it requires the user to hit enter. What you need is something like ncurses' getch()/ readline/ jLine as mentioned by @miku. With these, you actually wait for a single keystroke.

So you have multiple options:

1. Use ncurses / readline binding, for example https://code.google.com/p/goncurses/ or equivalent like https://github.com/nsf/termbox

2. Roll your own see http://play.golang.org/p/plwBIIYiqG for starting point

3. use os.Exec to run stty or jLine.

refs:

https://groups.google.com/forum/?fromgroups=#!topic/golang-nuts/zhBE5MH4n-Q

https://groups.google.com/forum/?fromgroups=#!topic/golang-nuts/S9AO_kHktiY

https://groups.google.com/forum/?fromgroups=#!topic/golang-nuts/icMfYF8wJCk

Assuming that you want unbuffered input (without having to hit enter), this does the job on UNIX systems:

package main

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

func main() {
    // 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()
    // restore the echoing state when exiting
    defer exec.Command("stty", "-F", "/dev/tty", "echo").Run()

    var b []byte = make([]byte, 1)
    for {
        os.Stdin.Read(b)
        fmt.Println("I got the byte", b, "("+string(b)+")")
    }
}