The SHELL and list are used to handle the transaction.

Command-1 & command-2 & command-3 & command-4 &... command-n

Every command returns the truth and will be executed in sequence. When a command returns false, the command chain will be broken.
The last one is false. It will be the last command to be executed.

Today, it's a shameful thing because of this blind spot in knowledge.
The testing machine of the company is on the rack of the data center. I went to the remote ssh and changed the network configuration to static access.
Then I want to restart eth0 to make it take effect: ifdown eth0, and the result is suspended.
Ssh fails to be logged on. Fortunately, it is a test machine. Run the machine room, move a monitor, log on locally, and run ifup eth0.

Use and list processing: ifdown eth0 & ifup eth0

After the network connection is disconnected, you just need to lock yourself out. You really need to do less in the future!