function users-without-mfa
    comm -13 (users-with-mfa | psub) (get users | psub)
end

function users-without-mfa
    comm -13 (users-with-mfa | sort | psub) (get users | sort | psub)
end

Sort results before piping to comm
Sort results before piping to comm

colstrom/shellops-aws,colstrom/piranha