-;;; Accept a file descriptor and move the file pointer ahead
-;;; a certain offset for that file. WHENCE can be any of the following:
-;;; L_SET Set the file pointer.
-;;; L_INCR Increment the file pointer.
-;;; L_XTND Extend the file size.
+;;; Is a stream interactive?
+(defun unix-isatty (fd)
+ (declare (type unix-fd fd))
+ (int-syscall ("isatty" int) fd))
+