blender python: texture change from command line

texture_change.py

'''
texture image path are relative to the blend file directory. run from command line like this:
 
texture=img/2012720989_c.jpg blender -b mug.blend --python texture_change.py -F PNG -s 1 -e 1 -j 1 -t 0 -a
''''
import os

image_file = os.getenv('texture')
if not image_file:
	image_file="img/2012720989_c.jpg"

PIC_obj="PIC"

import bpy
from bpy_extras.image_utils import load_image


bpy.ops.object.select_all(action = 'DESELECT')
bpy.data.objects[PIC_obj].select = True
bpy.context.scene.objects.active = bpy.data.objects[PIC_obj]

image_abs = bpy.path.abspath("//%s" % image_file)

image_name = os.path.split(image_file)[1]
bImg = bpy.data.images.get(image_name)
if not bImg:
	bImg = load_image(image_abs)
name_compat = bpy.path.display_name_from_filepath(bImg.filepath)

material_tree = bpy.data.materials.get("PIC").node_tree
links = material_tree.links

texture = bpy.data.textures.get(name_compat)
if not texture:
	texture = material_tree.nodes.new('ShaderNodeTexImage')
	texture.image = bImg
	texture.show_texture = True
	texture.name = name_compat 

emit = material_tree.nodes['Emission']
links.new(texture.outputs[0], emit.inputs[0]) 

It looks like you just have an object named "PIC" in the scene tree. Is that the only reference the script needs to find the texture and replace it? This script is hugely helpful, thanks so much for posting this.

Can you please tell me how the texture file (2012720989_c.jpg) looks like?