Index: src/OFStdIOStream.h
==================================================================
--- src/OFStdIOStream.h
+++ src/OFStdIOStream.h
@@ -51,10 +51,15 @@
 	bool _closable;
 #endif
 	bool _atEndOfStream;
 }
 
+/*!
+ * @brief Whether there is an underlying terminal.
+ */
+@property (readonly, nonatomic) bool hasTerminal;
+
 /*!
  * @brief The number of columns, or -1 if there is no underlying terminal or
  *	  the number of columns could not be queried.
  */
 @property (readonly, nonatomic) int columns;

Index: src/OFStdIOStream.m
==================================================================
--- src/OFStdIOStream.m
+++ src/OFStdIOStream.m
@@ -383,10 +383,19 @@
 
 - (unsigned int)retainCount
 {
 	return OF_RETAIN_COUNT_MAX;
 }
+
+- (bool)hasTerminal
+{
+#if defined(HAVE_ISATTY) && !defined(OF_AMIGAOS)
+	return isatty(_fd);
+#else
+	return false;
+#endif
+}
 
 - (int)columns
 {
 #if defined(HAVE_SYS_IOCTL_H) && defined(TIOCGWINSZ) && !defined(OF_AMIGAOS)
 	struct winsize ws;

Index: src/OFWin32ConsoleStdIOStream.m
==================================================================
--- src/OFWin32ConsoleStdIOStream.m
+++ src/OFWin32ConsoleStdIOStream.m
@@ -453,10 +453,19 @@
 	 * since any incomplete write is an exception here anyway, we can just
 	 * return length.
 	 */
 	return length;
 }
+
+- (bool)hasTerminal
+{
+	/*
+	 * We can never get here if there is no terminal, as the initializer
+	 * changes the class to OFStdIOStream in that case.
+	 */
+	return true;
+}
 
 - (int)columns
 {
 	CONSOLE_SCREEN_BUFFER_INFO csbi;