Q:

Does the US government have any planning in place to ensure there's no shortages of food, fuel, steel and other commodities?

Every time we go shopping store shelves are full of food, gas stations are stocked up on gas, car dealerships have no shortage of cars, etc. But who is ensuring that all of the complex processes required to maintain this state of affairs go smoothly? Is it just the free market doing its thing without any coordination? Or is there an office somewhere in DC where a big committee draws up a plan to ensure that no shortages take place in the foreseeable future? 

A:

Although the United States generally avoids economic planning (and even industrial policy), this is not to say the government leaves everything to the market. I don't have much expertise on this topic so I'm sure the following list will be incomplete. But here are some examples of ways that the federal government intervenes to ensure the continued availability of basic consumer products. 

Fuel and energy: 1) The Strategic Petroleum Reserve is an emergency supply of crude oil maintained by the federal government. This system was created as a response to shortages in the 1970s. It currently has about 30 days supply. 2) The Federal Energy Regulatory Commission oversees the development of energy transmission infrastructure like pipelines and the electrical grid.
Food: 1) The United States government has intermittently held strategic grain reserves. However since the 1970s at least, these seem to have been for foreign aid, not domestic consumption. 2) The USDA's National Agricultural Statistics Service closely monitors the national food supply month by month. 3) Other parts of the USDA provide subsidies, technical assistance, and other forms of support to farmers which help ensure an adequate food supply. 
General: The Federal Reserve tracks things like price inflation for durable goods, which may influence monetary policy and other measures. 

Finally I will note that during the Great Depression and especially during the two World Wars, federal intervention in the markets for basic commodities was far more active. See for example the War Production Board.

A:

To piggyback on the wonderful examples of US Reserves for crises in another answer, the short answer to your question is, roughly, no. More specifically, this question: 

But who is ensuring that all of the complex processes required to maintain this state of affairs go smoothly?

It is, in fact, the free market that makes sure all these complex processes go smoothly. There isn't any government body coordinating avocado farmers in Central America with distributors in Florida to purchase those avocados and get them to a Whole Foods near you.[1]
As described in another answer [linked above], there are reserves set aside in case of major crisis to ensure a shortage doesn't spiral out of control, but they're for just that - crises. With the exception of providing subsidies or tax breaks to incentivize production of some goods (corn subsidies, renewable energy tax breaks), the US government doesn't take an active role in controlling the market. 
The government notably doesn't take action to help with general "shortages" - there's no backup of Romaine for when an E. Coli outbreak occurs, they don't manage the supply of your favorite cola to make sure there's no shortage, they don't direct the supply chain for the new iPhone to guarantee they don't run out. All of that supply chain management is done by the individual companies - sellers (due to sales numbers, population counts, research, etc) think they need [some amount] of the product(s) they're selling, they buy that much from a supplier (who is thus a seller themselves, and may need research on how many to buy/produce), and so on.

1: This is purely for example, I'm not sure if there's any distributor in Florida, or if the maybe-exists distributor sells to Whole Foods.

