function similar to getchar

Question

Is there a Go function similar to C\'s getchar able to handle tab press in console? I want to make some sort of completion in my console app.

Answer 1

Other answers here suggest such things as:

• Using cgo

  • inefficient
  • "cgo is not Go"

• os.Exec of stty

  • not portable
  • inefficient
  • error prone

• using code that uses /dev/tty

  • not portable

• using a GNU readline package

  • inefficient if it's a wrapper to C readline or if implemented using one of the above techniques
  • otherwise okay

However, for the simple case this is easy just using a package from the Go Project's Sub-repositories.

Basically, use terminal.MakeRaw and terminal.Restore to set standard input to raw mode (checking for errors, e.g. if stdin is not a terminal); then you can either read bytes directly from os.Stdin, or more likely, via a bufio.Reader (for better efficiency).

For example, something like this:

package main

import (
    "bufio"
    "fmt"
    "log"
    "os"

    "golang.org/x/crypto/ssh/terminal"
)

func main() {
    // fd 0 is stdin
    state, err := terminal.MakeRaw(0)
    if err != nil {
        log.Fatalln("setting stdin to raw:", err)
    }
    defer func() {
        if err := terminal.Restore(0, state); err != nil {
            log.Println("warning, failed to restore terminal:", err)
        }
    }()

    in := bufio.NewReader(os.Stdin)
    for {
        r, _, err := in.ReadRune()
        if err != nil {
            log.Println("stdin:", err)
            break
        }
        fmt.Printf("read rune %q\r\n", r)
        if r == 'q' {
            break
        }
    }
}