From f34a3a68054eaad15d76c871eeabfa854df47dae Mon Sep 17 00:00:00 2001
From: Frank Szendzielarz <33515470+FrankSzendzielarz@users.noreply.github.com>
Date: Thu, 25 Jul 2019 13:46:42 +0200
Subject: [PATCH] cmd/clef: fix colored output on Windows (#19889)

* Fixes #19861 - coloured output

* cmd/clef: minor formatting nit

* cmd/clef: bleah, stupid github editor
---
 cmd/clef/main.go | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/cmd/clef/main.go b/cmd/clef/main.go
index 85ec5647c..5567fb8f5 100644
--- a/cmd/clef/main.go
+++ b/cmd/clef/main.go
@@ -53,6 +53,8 @@ import (
 	"github.com/ethereum/go-ethereum/signer/fourbyte"
 	"github.com/ethereum/go-ethereum/signer/rules"
 	"github.com/ethereum/go-ethereum/signer/storage"
+	colorable "github.com/mattn/go-colorable"
+	"github.com/mattn/go-isatty"
 	"gopkg.in/urfave/cli.v1"
 )
 
@@ -392,7 +394,13 @@ func initialize(c *cli.Context) error {
 		}
 		fmt.Println()
 	}
-	log.Root().SetHandler(log.LvlFilterHandler(log.Lvl(c.Int(logLevelFlag.Name)), log.StreamHandler(logOutput, log.TerminalFormat(true))))
+	usecolor := (isatty.IsTerminal(os.Stderr.Fd()) || isatty.IsCygwinTerminal(os.Stderr.Fd())) && os.Getenv("TERM") != "dumb"
+	output := io.Writer(logOutput)
+	if usecolor {
+		output = colorable.NewColorable(logOutput)
+	}
+	log.Root().SetHandler(log.LvlFilterHandler(log.Lvl(c.Int(logLevelFlag.Name)), log.StreamHandler(output, log.TerminalFormat(usecolor))))
+
 	return nil
 }