Bash

Subshells

https://tldp.org/LDP/abs/html/subshells.html

Parentheses () spawn a subshell, which is effectively a new sub-process. Interestingly, the spawned sub-shells are not forked off asynchronously by default, but require an explicit &.

# synchronous subshell

(
command
command
command
)

# control gets here after subshell is done

# asynchronous subshells (parallel)

(
command
command
command
) &

(
command
command
command
) &

# control gets here immediately

wait # wait until subshells are done
Edit