rostopic_echo.py

import rospy
from std_msgs.msg import String

def chunks(lst, n):
    """Yield successive n-sized chunks from lst."""
    for i in range(0, len(lst), n):
        yield lst[i:i + n]

def callback(data):
    rospy.loginfo(f'\n\ninput string: (#bytes: {len(data.data):,})')
    # rospy.loginfo(data.data)
    rospy.loginfo('hex:')
    for idx, line in enumerate(chunks(data.data, 10)):
        print(f'#{idx * 10:3d}\t\t\t{", ".join(f"{ord(c):02x}" for c in line)}')

    
def listener(topics):
    rospy.init_node('node_name')
    for topic in topics:
        rospy.Subscriber(topic, String, callback)
    # spin() simply keeps python from exiting until this node is stopped
    rospy.spin()

print('listening...')
listener(sys.argv[1:])