Overview
gz model command allows you to get information about the models for a given running Gazebo simulation.
For each model, it is possible to get information about its
- Pose: Pose of the model
 
- Links: Pose, mass, and inertial matrix of the link and attached sensors
 
- Joints: Parent link, child link and joint type.
 
Example running the diff_drive world
To try out this command we need first a running simulation. Let's load the diff_drive example world. In a terminal, run: 
gz sim diff_drive.sdf
 Once Gazebo is up, we can use the gz model command to get information of the simulation. Open a new terminal and enter: 
gz model --list
 And available models should be printed: 
Available models:
    - ground_plane
    - vehicle_blue
    - vehicle_green
 Once you get the name of the model you want to see, you may run the following commands to get its properties.
gz model -m <model_name> to get the complete information of the model. e.g. 
gz model -m vehicle_blue
 Requesting state for world [diff_drive]...
 
Model: [8]
- Name: vehicle_blue
- Pose [ XYZ (m) ] [ RPY (rad) ]:
        [0.000000 | 2.000000 | 0.325000]
        [0.000000 | 0.000000 | 0.000000]
 
- Link [9]
        - Name: chassis
        - Parent: vehicle_blue [8]
        - Mass (kg): [1.143950]
        - Inertial Pose [ XYZ (m) ] [ RPY (rad) ]:
                [0.000000 0.000000 0.000000]
                [0.000000 -0.000000 0.000000]
        - Inertial Matrix (kg⋅m^2):
                [0.126164 | 0.000000 | 0.000000]
                [0.000000 | 0.416519 | 0.000000]
                [0.000000 | 0.000000 | 0.481014]
        - Pose [ XYZ (m) ] [ RPY (rad) ]:
                [-0.151427 | 0.000000 | 0.175000]
                [0.000000 | 0.000000 | 0.000000]
- Link [12]
        - Name: left_wheel
        - Parent: vehicle_blue [8]
        - Mass (kg): [2.000000]
        - Inertial Pose:
                [0.000000 | 0.000000 | 0.000000]
        - Inertial Matrix (kg⋅m^2):
                [0.145833 | 0.000000 | 0.000000]
                [0.000000 | 0.145833 | 0.000000]
                [0.000000 | 0.000000 | 0.125000]
        - Pose [ XYZ (m) ] [ RPY (rad) ]:
                [0.554283 | 0.625029 | -0.025000]
                [-1.570700 | 0.000000 | 0.000000]
- Link [15]
        - Name: right_wheel
        - Parent: vehicle_blue [8]
        - Mass (kg): [2.000000]
        - Inertial Pose:
                [0.000000 | 0.000000 | 0.000000]
        - Inertial Matrix (kg⋅m^2):
                [0.145833 | 0.000000 | 0.000000]
                [0.000000 | 0.145833 | 0.000000]
                [0.000000 | 0.000000 | 0.125000]
        - Pose [ XYZ (m) ] [ RPY (rad) ]:
                [0.554282 | -0.625029 | -0.025000]
                [-1.570700 | 0.000000 | 0.000000]
- Link [18]
        - Name: caster
        - Parent: vehicle_blue [8]
        - Mass (kg): [1.000000]
        - Inertial Pose:
                [0.000000 | 0.000000 | 0.000000]
        - Inertial Matrix (kg⋅m^2):
                [0.100000 | 0.000000 | 0.000000]
                [0.000000 | 0.100000 | 0.000000]
                [0.000000 | 0.000000 | 0.100000]
        - Pose [ XYZ (m) ] [ RPY (rad) ]:
                [-0.957138 | 0.000000 | -0.125000]
                [0.000000 | 0.000000 | 0.000000]
- Joint [21]
        - Name: left_wheel_joint
        - Parent: vehicle_blue [8]
        - Type:  revolute
        - Parent Link: left_wheel
        - Child Link:  chassis
        - Pose [ XYZ (m) ] [ RPY (rad) ]:
        [0.000000 | 0.000000 | 0.000000]
        [0.000000 | 0.000000 | 0.000000]
        - Axis position [ XYZ ]:
        [0 | 0 | 1]
- Joint [22]
        - Name: right_wheel_joint
        - Parent: vehicle_blue [8]
        - Type:  revolute
        - Parent Link: right_wheel
        - Child Link:  chassis
        - Pose [ XYZ (m) ] [ RPY (rad) ]:
        [0.000000 | 0.000000 | 0.000000]
        [0.000000 | 0.000000 | 0.000000]
        - Axis position [ XYZ ]:
        [0 | 0 | 1]
- Joint [23]
        - Name: caster_wheel
        - Parent: vehicle_blue [8]
        - Type: ball
        - Parent Link: chassis [9]
        - Child Link: caster [18]
        - Pose [ XYZ (m) ] [ RPY (rad) ]:
            [0.000000 0.000000 0.000000]
            [0.000000 -0.000000 0.000000]
gz model -m <model_name> --pose to get the pose information. e.g. 
gz model -m vehicle_blue --pose
Requesting state for world [diff_drive]...
 
      Model: [8]
          - Name: vehicle_blue
          - Pose [ XYZ (m) ] [ RPY (rad) ]:
      [0.000000 | 2.000000 | 0.325000]
      [0.000000 | 0.000000 | 0.000000]
To get the information of all the model links enter 
gz model -m <model_name> --link
Or you can get the information of a single link by adding the name as argument. e.g. 
gz model -m vehicle_blue --link caster
 Requesting state for world [diff_drive]...
 
          - Link [18]
              - Name: caster
              - Parent: vehicle_blue [8]
              - Mass (kg): [1.000000]
              - Inertial Pose:
                      [0.000000 | 0.000000 | 0.000000]
              - Inertial Matrix (kg⋅m^2):
                      [0.100000 | 0.000000 | 0.000000]
                      [0.000000 | 0.100000 | 0.000000]
                      [0.000000 | 0.000000 | 0.100000]
              - Pose [ XYZ (m) ] [ RPY (rad) ]:
                      [-0.957138 | 0.000000 | -0.125000]
                      [0.000000 | -0.000000 | 0.000000]
To get the information of all the model joints enter 
gz model -m <model_name> --joint
 Or you can get the information of a single joint by adding the name as argument. e.g. 
gz model -m vehicle_blue --joint caster_wheel
 Requesting state for world [diff_drive]...
 
          - Joint [23]
              - Name: caster_wheel
              - Parent: vehicle_blue [8]
              - Type:  ball
              - Parent Link: caster
              - Child Link:  chassis
              - Pose [ XYZ (m) ] [ RPY (rad) ]:
                  [0.000000 | 0.000000 | 0.000000]
                  [0.000000 | -0.000000 | 0.000000]