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What is && in bash? In bash—and many other programming languages—&& means “AND”.
And in command execution context like this, it means items to the left as well as right of && should be run in sequence in this case.

What is & in bash? And a single & means that the preceding commands—to the immediate left of the &—should simply be run in the background.

http://stackoverflow.com/questions/26770568/vs-with-the-test-command-in-bash