[Jtsummers]

It's a mixed bag. Some jobs are deemed essential or exempted and so those individuals have to work. But not all are. Most of NASA, for instance, is shutdown as their work isn't considered critical or exempted.

Exempted: Usually a result of the way it's funded. Some government work is funded by the budget, directly. Others essentially pay for themselves (the government workers acting in essence as contractors or a business, they receive payments from others besides the Congress to do work). Most of those have funding that would last 2-6 weeks. They get to stay open.

None of these people were going to get paid during the shutdown, but they were still expected to work. Their paychecks after the shutdown would pay them. Essentially they're guaranteed the pay, but the pay date would slip.

Although now it's a moot point as it looks like the shutdown is ending.