The original Quake 2 sources as originally released under the GPL license on December 21, 2001.

linux/in_linux.c

@@ -0,0 +1,29 @@
+// in_null.c -- for systems without a mouse
+
+#include "../client/client.h"
+
+cvar_t	*in_mouse;
+cvar_t	*in_joystick;
+
+void IN_Init (void)
+{
+    in_mouse = Cvar_Get ("in_mouse", "1", CVAR_ARCHIVE);
+    in_joystick = Cvar_Get ("in_joystick", "0", CVAR_ARCHIVE);
+}
+
+void IN_Shutdown (void)
+{
+}
+
+void IN_Commands (void)
+{
+}
+
+void IN_Move (usercmd_t *cmd)
+{
+}
+
+void IN_Activate (qboolean active)
+{
+}
+