Add single line json output (#3739)

cmd/globals.go

@@ -57,6 +57,7 @@ const (
 var (
 	globalQuiet    = false // Quiet flag set via command line
 	globalJSON     = false // Json flag set via command line
+	globalJSONLine = false // Print json as single line.
 	globalDebug    = false // Debug flag set via command line
 	globalNoColor  = false // No Color flag set via command line
 	globalInsecure = false // Insecure flag set via command line
@@ -76,8 +77,9 @@ var (
 func setGlobals(quiet, debug, json, noColor, insecure bool) {
 	globalQuiet = globalQuiet || quiet
 	globalDebug = globalDebug || debug
+	globalJSONLine = !isTerminal() && json
 	globalJSON = globalJSON || json
-	globalNoColor = globalNoColor || noColor
+	globalNoColor = globalNoColor || noColor || globalJSONLine
 	globalInsecure = globalInsecure || insecure
 
 	// Disable colorified messages if requested.

cmd/print.go

@@ -18,6 +18,10 @@
 package cmd
 
 import (
+	"bytes"
+	"encoding/json"
+	"strings"
+
 	"github.com/minio/pkg/console"
 )
 
@@ -34,6 +38,13 @@ func printMsg(msg message) {
 		msgStr = msg.String()
 	} else {
 		msgStr = msg.JSON()
+		if globalJSONLine && strings.ContainsRune(msgStr, '\n') {
+			// Reformat.
+			var dst bytes.Buffer
+			if err := json.Compact(&dst, []byte(msgStr)); err == nil {
+				msgStr = dst.String()
+			}
+		}
 	}
 	console.Println(msgStr)
 }