+ * @PermissionDenied@: The process has insufficient privileges to
+ perform the operation.
+
+ * @ResourceExhausted@: Insufficient resources are available to
+ perform the operation.
+
+ * @UnsupportedOperation@: The implementation does not support
+ system calls.
+
+On Windows, 'system' is implemented using Windows's native system
+call, which ignores the @SHELL@ environment variable, and always
+passes the command to the Windows command interpreter (@CMD.EXE@ or
+@COMMAND.COM@), hence Unixy shell tricks will not work.
+-}