convert_dae_to_obj.py

## Example command-line usage: $ for i in *.dae; do echo $i; blender -b --python convert.py -- $i ${i%.dae}.obj; done
## Need to be careful about face normals direction of exported object

import bpy
import sys

argv = sys.argv
argv = argv[argv.index("--") + 1:] # get all args after "--"                                                                             

dae_in = argv[0]
obj_out = argv[1]

while bpy.data.objects:
    bpy.data.objects.remove(bpy.data.objects[0], do_unlink=True)

bpy.ops.wm.collada_import(filepath=dae_in)
bpy.ops.export_scene.obj(filepath=obj_out, axis_forward='Y', axis_up='Z', use_materials=False)