Use ANSI code to test color capabilites of a terminal

256color.go

// Test terminals color capabilities

package main

import "fmt"

func main() {
        const (
                normal    = "\033[0m"
                color     = "\033[%d;%dm"
                fgcolor2  = "\033[38;5;%dm"
                bgcolor2  = "\033[48;5;%dm"
                fgcolor24 = "\033[38;2;%d;%d;%dm"
                bgcolor24 = "\033[48;2;%d;%d;%dm"
                clear     = "\033[2J"
                pos       = "\033[%d;%dH"
        )
  
        // 8 bits
        // 8 Normal Colors
        // 0-7
        fmt.Println("8 Normal colors")
        for i := 0; i < 8; i++ {
                fmt.Printf(color+" %d ", 0, 40+i, i)
        }
        fmt.Println(normal + "\n")
  
        // 8 Bright Colors
        // 8-15
        fmt.Println("8 Bright colors")
        for i := 0; i < 8; i++ {
                fmt.Printf(color+" %d ", 0, 100+i, i)
        }
        fmt.Println(normal + "\n")
  
        // 6 x 6 x 6 color cube
        // color = 16 + 36 x r + 6 x g + b
        // 16-231
        fmt.Println("6x6x6 color cube")
        for r := 0; r < 6; r++ {
                for g := 0; g < 6; g++ {
                        for b := 0; b < 6; b++ {
                                c := 16 + 36*r + 6*g + b
                                fmt.Printf(bgcolor2+" %3d  ", c, c)
                        }
                        fmt.Printf(normal + " ")
                }
                fmt.Println("")
        }
        fmt.Println(normal)
  
        // Gray scale
        // 232-255
        fmt.Println("Gray scale")
        for i := 232; i < 256; i++ {
                fmt.Printf(bgcolor2+" %d ", i, i)
        }
        fmt.Println(normal + "\n")
  
        // 24 bits
        fmt.Println("Nice 24bits color square")
        for r := 0; r < 60; r++ {
                for g := 0; g < 1; g++ {
                        for b := 0; b < 60; b++ {
                                fmt.Printf(bgcolor24+"  ", r, g, b)
                        }
                        fmt.Printf(normal)
                }
                fmt.Println("")
        }
        fmt.Println(normal)
}