How do I setblock a command

How do I setblock a command block that's repeating, always active, and has a command? I need it for a one command block creation.

1.12-:

setblock <x> <y> <z> repeating_command_block 0 replace {Command:"Command",auto:1b}

1.13+:

setblock <x> <y> <z> repeating_command_block{Command:"Command",auto:1b}

You can also just change the command block configuration inside the command block GUI.

I wouldn't suggest making a single command block creation in game - try either notepad or this handy tool; https://mrgarretto.com/commanddump

If you where wondering, /summon FallingSand ~ ~1 ~ {Block:redstone_block,Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:"/fill ~ ~0 ~1 ~ ~-1 ~1 redstone_block"},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:"your command"},Time:1,Riding:{id:"FallingSand",Block:stone,Time:1}}}} is a good start since it can be manipulated for multiple commands.

For example, two commands: /summon FallingSand ~ ~1 ~ {Block:redstone_block,Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:"/fill ~ ~0 ~1 ~ ~-3 ~1 redstone_block"},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:"Command 1"},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:"\n"},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:"Command 2"},Time:1,Riding:{id:"FallingSand",Block:stone,Time:1}}}}}}

I don't suggest having a repeating command block placed somewhere for a one command block creation.