Blender python expression string not working when used with Rez

[johhnry]

Hi,

I am using Blender on Windows on the render farm and I want to pass a python expression with the --python-expr option (see https://docs.blender.org/manual/en/latest/advanced/command_line/arguments.html):

rez env blender -- blender 
  --background
  -noaudio monkey.blend
  --python-expr "import bpy; bpy.context.scene.render.use_overwrite = False"
  --render-format PNG
  --engine CYCLES
  --render-output render.#### 
  --log-level 0 
  --render-frame 1

The issue is that it doesn't work when using it in a rez environment, looks like the arguments are parsed in some way:

Blender 3.1.2 (hash cc66d1020c3b built 2022-03-31 23:39:57)
Read prefs: C:\Users\etudiant\AppData\Roaming\Blender Foundation\Blender\3.1\config\userpref.blend
Read blend: P:\test_pipe\shots\s01\p010\animation_main\publish\v000\blend\monkey.blend
Error: Python:   File "<string>", line 1
    import
          ^
SyntaxError: invalid syntax

location: <unknown location>:-1

Python:   File "<string>", line 1
    import
          ^
SyntaxError: invalid syntax

location: <unknown location>:-1
Error: Cannot read file 'C:\Users\etudiant\bpy;': No such file or directory

Blender quit

But it works when using the executable directly:

$ C:\some\path\to\blender.exe 
  --background
  -noaudio monkey.blend
  --python-expr "import bpy; bpy.context.scene.render.use_overwrite = False"
  --render-format PNG
  --engine CYCLES
  --render-output render.####
  --log-level 0
  --render-frame 1

Blender 3.1.2 (hash cc66d1020c3b built 2022-03-31 23:39:57)
Read prefs: C:\Users\etudiant\AppData\Roaming\Blender Foundation\Blender\3.1\config\userpref.blend
Read blend: monkey.blend
skipping existing frame "render.0001.png"
Info: No frames rendered, skipped to not overwrite

Blender quit

Do someone have any idea why it would do that?

Details

• Windows 10
• Rez 2.95.0
• Blender 3.1.2

[Sookhaal]

Probably same as #1133
Have you tried escaping the double quotes or updating rez to at least 2.95.3?

[johhnry]

Hi @Sookhaal,

Thanks for the answer, it works! (I had to put the python-expr option after the .blend file to take effect on the scene also ;) )

rez env blender test_pipe -- blender 
  --background
  -noaudio monkey.blend
  --python-expr \"import bpy; print(bpy.context.scene.render.use_overwrite); bpy.context.scene.render.use_overwrite = False\"
  --render-format PNG
  --engine CYCLES
  --render-output render.####
  --log-level 0
  --render-frame 1
  -- --cycles-device OPTIX