answers.ros.org <arg name="node_start_delay" default="1.0" /> <node name="listener" pkg="roscpp_tutorials" type="listener" launch-prefix="bash -c 'sleep $(arg node_start_delay); $0 $@' " /></node></arg>

demura.net import sys sys.path.remove('/opt/ros/melodic/lib/python2.7/dist-packages')

ここを参考に www.mech.tohoku-gakuin.ac.jp