You can export Gmsh geometry in a Python environment by using the Python bindings that are provided with Gmsh. The process for doing this is as follows:

1. First, you need to import the gmsh module in Python. This can be done by running “import gmsh”
2. Next, initialize the Gmsh library by calling “gmsh.initialize()”. This will set up the Gmsh environment and allow you to use its functions in Python.
3. Then, you can create a new Gmsh model by calling “gmsh.model.add(“model_name”)”
4. Once you have a model, you can create geometry using Gmsh’s built-in functions such as “gmsh.model.geo.addPoint(x, y, z, lc)” , “gmsh.model.geo.addLine(p1, p2)” , “gmsh.model.geo.addCurveLoop(lines)” , etc.
5. Once you have your geometry defined, you can export it to a file format such as .stl, .vtk, .unv, .msh, etc. by calling the corresponding gmsh.model.mesh.generate function.
6. Finally, you should close the Gmsh environment by calling “gmsh.finalize()”

Here is an example of a script that exports a 3D geometry to a .stl file:

import gmsh

gmsh.initialize()
gmsh.model.add("example")

#create geometry
gmsh.model.geo.addPoint(0, 0, 0, 0.1)
gmsh.model.geo.addPoint(1, 0, 0, 0.1)
gmsh.model.geo.addPoint(1, 1, 0, 0.1)
gmsh.model.geo.addPoint(0, 1, 0, 0.1)

# create line loops
line_loop = gmsh.model.geo.addCurveLoop([1,2,3,4])

#create surface
gmsh.model.geo.addPlaneSurface([line_loop])

# generate mesh
gmsh.model.mesh.generate(2)

# export to .stl
gmsh.write("example.stl")

gmsh.finalize()

STL format is typically used for solid models. If you want to export point and line data instead, you can use a different file format that is better suited for that purpose. Some examples of file formats that can be used to export point and line data include:

• CSV (Comma Separated Values): This is a simple text file format that can be easily opened and edited in a spreadsheet program like Excel. You can export point and line data as separate columns in a CSV file, with each row representing a different point or line.
• VTK (Visualization Toolkit): This is a file format that is commonly used for scientific visualization and can store both point and line data. You can use the gmsh.write(“example.vtk”) function to export the point and line data to a VTK file
• UNV (Universal Format): This is a file format that is commonly used in the field of finite element analysis and can store both point and line data, among other types of data.
• MSH (Gmsh Mesh format): This is a file format that is native to Gmsh and can store both point and line data, along with other types of data such as elements, nodes, etc.

You can export point and line data in these formats by calling the corresponding export functions. For example, to export the point and line data to a VTK file, you can use the command “gmsh.write(“example.vtk”)”.

It’s also important to notice that depending on the format, you may need to generate the mesh and/or the post-processing data before exporting it, as some of these formats may require that information in order to be written.