I think that what you are asking for is:

echo 1 && { echo 2 & } && echo 3 && echo 4

In the above echo 1 runs in foreground but echo 2 runs background.

Note that the && after echo 2 may not be doing what you think. Consider:

$ echo 1 && { false & } && echo 3 && echo 4

1

[2] 28445

3

4

The above shows that echo 3 runs even though the second command false returns failure. This is because the return code for the background process is not available when the decision to start echo 3 is made.

Let's consider your more realistic example:

compile && { run server & } && run test 1 && run test 2 && kill server

run test 1 will start regardless of whether run server succeeded or failed. Worse than that, run test 1 may start before run server has finished setting up the server. A quick fix is to delay run test 1 by enough time that you are confident that run server has finished doing its setup:

compile && { run server & } && sleep 1 && run test 1 && run test 2 && kill server

Alternatively, you would need to know something about run server so that you can test its successful setup.

Background

• The braces, {...}, create a list. Thus the construct { echo 2 & } allows us to run echo 2 with the effect of the operator & confined to just the commands in the list.




• && is bash's logical and. The command following the && is run only if the prior command succeeds, that is, returns with code 0.