Retrieve the first/last line of subshell stdout

Question

If I have a subshell command:

output="$(runfoo)";

is there way to store only the last line of the output from runfoo into the variable output? Or perhaps only the first line?

Answer 1

Only stdout:

output="$(runfoo | tail -n 1)"

output="$(runfoo | head -n 1)"

Stdout and stderr:

output="$(runfoo 2>&1 | tail -n 1)"

output="$(runfoo 2>&1 | head -n 1)"