Can you make me a blender script in python to copy all the lights present in the scene?
Certainly! Here's a Blender Python script that will copy all lights in the current scene:
``` 
import bpy

# Get a list of all objects in the scene
scene = bpy.context.scene
all_objects = scene.objects

# Loop through each object and check if it's a light
for obj in all_objects:
    if obj.type == 'LIGHT':
        # Duplicate the light object
        new_obj = obj.copy()
        # Link the new object to the scene
        scene.collection.objects.link(new_obj)
``` 
This script will loop through all objects in the current scene, check if the object is a light, and duplicate it if it is. The duplicated light will be linked to the scene and will have a new name (e.g. Light.001).

You can save this script as a .py file and run it from the Blender text editor or by calling Blender from the command line with the --python option. For example, if your script is saved as copy_lights.py, you can run it with the following command:
``` 
blender --background --python copy_lights.py
``` 
This will open Blender in background mode, run the script, and then close Blender.
how do I check if I have blender properly installed from the command line? Assume I am using a normal unix terminal
To check if Blender is installed and working from the command line, you can:

Try running blender --version. If Blender is installed and on your PATH, this should print out the Blender version number.
Try running a simple Blender script. For example, create a script called test.py with just the line import bpy, then run blender --background --python test.py. If Blender launches and imports the script successfully, it's installed and working.
Try launching Blender's GUI by just running blender. If the Blender interface opens, it's installed and working.

So to summarize, here are three ways to check Blender is installed from the command line:

blender --version
blender --background --python test.py (where test.py is a simple script importing bpy)
blender (to launch the GUI)

Any of those succeeding would indicate Blender is installed and working on your system.