Set the value of a cgroup parameter for a container.

    path
        path to the container parent directory
        default: /var/lib/lxc (system)

        .. versionadded:: 2015.8.0

    CLI Example:

    .. code-block:: bash

        salt '*' lxc.set_parameter name parameter value

def set_parameter(name, parameter, value, path=None):
    '''
    Set the value of a cgroup parameter for a container.

    path
        path to the container parent directory
        default: /var/lib/lxc (system)

        .. versionadded:: 2015.8.0

    CLI Example:

    .. code-block:: bash

        salt '*' lxc.set_parameter name parameter value
    '''
    if not exists(name, path=path):
        return None

    cmd = 'lxc-cgroup'
    if path:
        cmd += ' -P {0}'.format(pipes.quote(path))
    cmd += ' -n {0} {1} {2}'.format(name, parameter, value)
    ret = __salt__['cmd.run_all'](cmd, python_shell=False)
    if ret['retcode'] != 0:
        return False
    else:
        return True