file command misclassifying python bytecode as dBase III DBT file

Question

I'm using cx-Freeze to freeze a PyQt5 application. On my Jenkins slave running OSX 10.13, when cx-Freeze is using the file command to check the type of the files, it classifies a .pyc file (python bytecode) as a dBase III DBT file with some non-utf-8 characters in the output:

$>file ./__pycache__/archive_util.cpython-35.opt-2.pyc
./__pycache__/archive_util.cpython-35.opt-2.pyc: dBase III DBT, version number 0, next free block index 168627479, 1st item "N)?warn)?DistutilsExecError)?spawn)?mkpath)?log)getpwnam)getgrnamc"

When I run the file command on the same file on my own Mac OS, I get the correct classification:

$>file ./__pycache__/archive_util.cpython-35.opt-2.pyc
./__pycache__/archive_util.cpython-35.opt-2.pyc: python 3.5.2+ byte-compiled

What could possibly make file command to behave that way in the Jenkins build machine?

Answer 1

It's probably a different version of the file command with a different magic file /usr/share/file/magic.mgc (see the source files /usr/share/file/magic/database for the "dBase III" definitions and /usr/share/file/magic/python for python) or your pyc files are different (different python version and/or code) and file has a false match on Jenkins.

Have you compared the files or swapped them and run file on them again? If both files are the same, it must be a different magic.mgc file (or if it is missing different source files or a different configuration like a MAGIC environment variable, but that's not very likely).