tasklog: check for connected tty on the actual writer

commands/commands.go

@@ -30,8 +30,8 @@ import (
 var (
 	Debugging    = false
 	ErrorBuffer  = &bytes.Buffer{}
-	ErrorWriter  = io.MultiWriter(os.Stderr, ErrorBuffer)
-	OutputWriter = io.MultiWriter(os.Stdout, ErrorBuffer)
+	ErrorWriter  = newMultiWriter(os.Stderr, ErrorBuffer)
+	OutputWriter = newMultiWriter(os.Stdout, ErrorBuffer)
 	ManPages     = make(map[string]string, 20)
 	tqManifest   = make(map[string]*tq.Manifest)
 

commands/multiwriter.go

@@ -0,0 +1,26 @@
+package commands
+
+import (
+	"io"
+	"os"
+)
+
+type multiWriter struct {
+	writer io.Writer
+	fd     uintptr
+}
+
+func newMultiWriter(f *os.File, writers ...io.Writer) *multiWriter {
+	return &multiWriter{
+		writer: io.MultiWriter(append([]io.Writer{f}, writers...)...),
+		fd:     f.Fd(),
+	}
+}
+
+func (w *multiWriter) Write(p []byte) (n int, err error) {
+	return w.writer.Write(p)
+}
+
+func (w *multiWriter) Fd() uintptr {
+	return w.fd
+}

tasklog/log.go

@@ -27,6 +27,9 @@ type Logger struct {
 	// this logger is running within.
 	widthFn func() int
 
+	// tty is true if sink is connected to a terminal
+	tty bool
+
 	// forceProgress forces progress status even when stdout is not a tty
 	forceProgress bool
 
@@ -81,11 +84,25 @@ func NewLogger(sink io.Writer, options ...Option) *Logger {
 		option(l)
 	}
 
+	l.tty = tty(sink)
+
 	go l.consume()
 
 	return l
 }
 
+type hasFd interface {
+	Fd() uintptr
+}
+
+// tty returns true if the writer is connected to a tty
+func tty(writer io.Writer) bool {
+	if v, ok := writer.(hasFd); ok {
+		return isatty.IsTerminal(v.Fd())
+	}
+	return false
+}
+
 // Close closes the queue and does not allow new Tasks to be `enqueue()`'d. It
 // waits until the currently running Task has completed.
 func (l *Logger) Close() {