How to clear current line in terminal

[Alex Mills]

Using Node.js with several projects I can use these:

const rl = require('readline');

process.stdout.write('current line')

rl.clearLine(process.stdout); 

rl.cursorTo(process.stdout, 0);

this will clear the current line in the terminal, so I can achieve something like a status line, but I cannot figure out how to do this with Golang, anyone know?

[Joop Kiefte]

I tend to do that with ANSI terminal codes, there are pages that explain all codes

Joop Kiefte - Chat @ Spike

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[Alex Mills]

Yeah I tried all those ANSI codes, nothing seems to work :(

[Joop Kiefte]

Can you give some example code?

Joop Kiefte - Chat @ Spike

[Alexander Mills]

Yeah sure so it looks like:

clearCurrentLine()  // clears the previous status line

fmt.Println("foo")

writeStatusLine()   // writes new status line

where clearCurrentLine() is just like

func clearCurrentLine(){

//fmt.Printf("\033[0;") // clear current line
//fmt.Printf("\033[2K\r%d",0);
//fmt.Fprint(os.Stdout,"\033[y;0H")
//fmt.Fprint(os.Stdout, "\033[K")
//fmt.Print("\x1b[2k") // erase the current line

}

I tried all those ANSI codes, nothing quite worked?

[Joop Kiefte]

package main

import "fmt"

func main() {
fmt.Println("Test 1")
fmt.Println("Test 2")
fmt.Print("\033[1A\033[K") //one up, remove line (should work after the newline of the Println)
}

Maybe this piece of code helps you?

Joop Kiefte - Chat @ Spike

To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/fe78a2dc-1d64-4502-ad3a-8a9e5ff0380fn%40googlegroups.com.

[Joop Kiefte]

func clearCurrentLine(){
     fmt.Print("\n\033[1A\033[K")
}

Joop Kiefte - Chat @ Spike

[Stephan Lukits]

On 9/19/20 10:45 AM, Alex Mills wrote:
> [...]

> this will clear the current line in the terminal, so I can achieve
> something like a status line, but I cannot figure out how to do this
> with Golang, anyone know?

https://play.golang.org/p/B5ZShtSizEy

[Stephen Illingworth]

This is how I would do it. Note that you must be careful not to insert newlines. If you do, terminal control becomes trickier.

package main

import "fmt"

// ClearLine is the CSI sequence to clear the entire of the current line.
const ClearLine = "\033[2K"

func main() {
    // print a string that is comparatively long
    fmt.Printf("hello world")

    // clear line
    fmt.Printf(ClearLine)

    // the line is cleared but the cursor is in the wrong place. the carriage
    // return moves the cursor to the beginning of the line.
    fmt.Printf("\r")

    // print a shorter string to show that the longer string has been cleared
    fmt.Printf("bye")

    // print a newline to move the cursor to next line of terminal
    fmt.Printf("\n")