I am trying to make a command block that when a player walks over a block, it will detect the player and activate another command block with a different command. I tried:
/testfor @p {coordinates of the block}
but this doesn't work.
According to this page from the Minecraft wiki, you also need to specify a radius within the block to check for the player.
To count the number of players in survival mode within a 3-block radius of (0,64,0):
testfor @a[0,64,0,r=3,m=0]
(The r=
isn't strictly necessary, but it makes the command a little clearer.)
/execute if entity @a[x=0,y=64,z=0,distance=..3,gamemode=survival]