scala>   val log = new ProcessLogger {
     |     val sb = new StringBuilder
     |     override def buffer[T](f: => T): T = f
     |     override def out(s: => String): Unit = sb.append(s)
     |     override def err(s: => String): Unit = sb.append(s)
     |   }
log: scala.sys.process.ProcessLogger{val sb: StringBuilder} = $anon$1@41385767

scala>   ("yes -y 100" #| "head -c 1").!(log)
res3: Int = 0

scala> log.sb.toString();
warning: there were 1 feature warning(s); re-run with -feature for details
res4: String = yes : option invalide -- 'y'Saisissez « yes --help » pour plus d'informations.