Running blender with either

blender --verbose


blender --debug-value

returns Error: you must specify a verbosity level.

The wiki page about command line options does not specify what these options do or what values they accept.

What are some values that these options accept, and what do they do?

  • $\begingroup$ Did you try --verbose 1 or 2 (or any integer)? $\endgroup$ Sep 23, 2013 at 9:11
  • $\begingroup$ @RóbertLászlóPáli yes, but I couldn't see any differences. $\endgroup$
    – gandalf3
    Sep 23, 2013 at 17:26

1 Answer 1


Both these arguments are mainly for developers.

  • --verbose is currently only used by libmv (camera tracking), however we will likely use in the future to control other output.
  • --debug-value is mainly for developers to test alternative behavior, from Python you can access it from bpy.app.debug_value from C/C++ you can access it from G.debug_value (with BKE_global.h include).

For example --debug-value 2 makes the manipulator rotation handles draw differently.

For verbose logging with camera tracking use --verbose 2.

  • $\begingroup$ Wow, thanks. it just so happens that I wanted verbosity for camera tracking. (trying to reproduce this) $\endgroup$
    – gandalf3
    Sep 25, 2013 at 1:36
  • $\begingroup$ How about adding this to the Blender documentation? This is the about third time I stumbled over this, wasted my time trying to get more info and the verbose value gets totally ignored, it does nothing. Please specify that it is NOT a general verbose value (as the man page or help suggest), but a specific one. $\endgroup$ Jun 7, 2019 at 1:08

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