minetest.conf is the configuration file used for numerous purposes. This file is read every time the game starts and is always created/modified when the menu quits.
The configuration file is located in one of these locations:
../minetest.conf- (RUN_IN_PLACE version, relative to executable)
../../minetest.conf- (RUN_IN_PLACE version, relative to executable)
~/.minetest/minetest.conf- (globally installed version on Linux)
A custom path to a configuration file can be specified in command line using the option
A file called minetest.conf.example is provided as an example. See that file for a more complete list of options.
This C++ code automatically generates minetest.conf, it contains all the default settings: 
fullscreen = false screenW = 800 screenH = 600 vsync = false video_driver = opengl enable_clouds = true enable_3d_clouds = true new_style_leaves = true opaque_water = false new_style_water = false smooth_lighting = true enable_fog = true wanted_fps = 30 fps_max = 60 viewing_range_nodes_min = 35 viewing_range_nodes_max = 160 view_bobbing_amount = 1.0 desynchronize_mapblock_texture_animation = true fsaa = false fullscreen_bpp = 24 enable_texture_atlas = true enable_farmesh = false farmesh_trees = true farmesh_distance = 40 console_color = (0,0,0) console_alpha = 192 enable_sound = true sound_volume = 0.5 creative_mode = false enable_damage = true fast_move = true free_move = false time_speed = 96 default_game = minetest only_peaceful_mobs = false give_initial_stuff = false active_object_send_range_blocks = 3 active_block_range = 2 server_map_save_interval = 5.3 ignore_world_load_errors = false motd = disallow_empty_password = false enable_pvp = true default_privs = interact,shout max_users = 100 unlimited_player_transfer_distance = true strict_protocol_version_checking = true disable_anticheat = false enable_rollback_recording = false max_simultaneous_block_sends_per_client = 2 max_simultaneous_block_sends_server_total = 8 max_block_send_distance = 10 max_block_generate_distance = 6 time_send_interval = 5 full_block_send_enable_min_time_from_building = 2.0 server_unload_unused_data_timeout = 29 dedicated_server_step = 0.05 address = name = port = 30000 client_unload_unused_data_timeout = 600 texture_path = ../textures/all screenshot_path = ../sceeenshots selected_mainmenu_tab = 0 selected_world_path = keymap_forward = KEY_KEY_W keymap_backward = KEY_KEY_S keymap_left = KEY_KEY_A keymap_right = KEY_KEY_D invert_mouse = false keymap_jump = KEY_SPACE keymap_sneak = KEY_LSHIFT keymap_inventory = KEY_KEY_I keymap_special1 = KEY_KEY_E aux1_descends = false keymap_chat = KEY_KEY_T keymap_cmd = / keyman_console = KEY_F10 keymap_rangeselect = KEY_KEY_R keymap_freemove = KEY_KEY_K keymap_fastmove = KEY_KEY_J keymap_screenshot = KEY_F12 keymap_print_debug_stacks = KEY_KEY_P keymap_quicktune_prev = KEY_HOME keymap_quicktune_next = KEY_END keymap_quicktune_dec = KEY_NEXT keymap_quicktune_inc = KEY_PRIOR random_input = false continuous_forward = false
video_driver = direct3d9 address = creative_mode = 0 enable_3d_clouds = 0 enable_damage = 1 name = new_style_leaves = 0 opaque_water = 0 port = 30000 smooth_lighting = 1
|video_driver||string||direct3d9|| Allows the user to chose the video renderer used to render Minetest.
|address||string||blank||The address used for connecting to a server, if it is blank, the game will start a local server when attempting to connect.|
|port||integer||30000||The port used when connecting to, or creating a server.|
|creative_mode||boolean||0|| Allows the user to enter creative mode. This only affects local server.
|enable_damage||boolean||0|| Allows the user to enable damage for their player. This only affects local server.
|name||string||blank||The name of the player in-game.|
|new_style_leaves||boolean||0|| Whether to make leaves transparent or opaque; opaque leaves are faster, thus recommended on slower computers.
|opaque_water||boolean||0|| Whether to enable opaque water.
|show_debug||boolean||0|| Whether to enable debug info (coordinates, draw times...) on startup.
|smooth_lighting||boolean||1|| Whether to use smooth lighting.
|client_delete_unused_sectors_timeout||integer||600||This will set the client to delete parts of the map from memory when they haven't been accessed for N seconds.|
|enable_texture_atlas||boolean||1||You can disable the building of the texture atlas with this line. (A texture atlas is a big texture with multiple smaller textures tiled in it).|
|invert_mouse||boolean||0|| Allows the user to invert their mouse vertical axis.
|texture_path||string||blank||Allows the user to specify an additional texture directory, from which Minetest will first search for textures.|
|time_speed||integer||72||This changes the speed of the server time (also applies to local/singleplayer game). When set to 0, the day/night cycle stops. The higher is the value, the faster the day/night cycle will be.|
|viewing_range_nodes_min||integer||25||Allows the user to change their minimal view range. This is very useful for slow computers.|
|viewing_range_nodes_max||integer||160||Allows the user to change their maximal view range. This is very useful for slow computers.|
|fov||integer||72||Allows the user to change their field of view.|
|view_bobbing||boolean||1|| Whether to enable view and wielded tool bobbing.
|view_bobbing_amount||float||1.0||Controls view bobbing intensity, 1.0 being 100%, 1.5 being 150% and so on.|
|enable_fog||boolean||1|| Whether to fog out the end of the visible area.
|enable_clouds||boolean||1|| Whether to draw clouds.
|enable_3d_clouds||boolean||0|| Allows the user to enable 3D clouds.
|enable_sound||boolean||1|| Whether to enable sound; sound can only be enabled if you have installed OpenAL.
|sound_volume||float||0.8||Allows the user to change sound volume. 1 is 100% volume whereas 0 is 0% volume.|
The key bindings are configurable in the "settings" menu.