[Bug 1585696] Re: command-not-found clashes with local python3 in path

[Launchpad Bug Tracker]

This bug was fixed in the package command-not-found - 0.3ubuntu16.10.0

---------------
command-not-found (0.3ubuntu16.10.0) yakkety; urgency=medium

  * command-not-found: Specify full path to python3 (LP: #1585696)
  * debian/rules: rm UnifiedDataExtractor/scan.data-old on clean.
  * Update data for yakkety, and add s390x database (LP: #1593592)

 -- Adam Conrad <adconrad at ubuntu.com>  Fri, 17 Jun 2016 00:41:31 -0600

** Changed in: command-not-found (Ubuntu)
       Status: New => Fix Released

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https://bugs.launchpad.net/bugs/1585696

Title:
  command-not-found clashes with local python3 in path

Status in command-not-found package in Ubuntu:
  Fix Released

Bug description:
  In Ubuntu 14.04 (and Linux Mint 17), /etc/bash.bashrc handles "command
  not found" with the function command_not_found_handle, which contains
  the line:

  /usr/bin/python /usr/lib/command-not-found -- $1

  However, /usr/lib/command-not-found was rewritten for Python 3. To
  handle this, /usr/lib/command-not-found has (lines 17-22):

  if sys.version < '3':
      # We might end up being executed with Python 2 due to an old
      # /etc/bash.bashrc.
      import os
      if "COMMAND_NOT_FOUND_FORCE_PYTHON2" not in os.environ:
          os.execvp("python3", [sys.argv[0]] + sys.argv)

  This catches old versions of python and re-runs command-not-found with
  python3 from the path. If a local version of Python (such as Anaconda)
  is installed, command-not-found will try to execute with the local
  python3 and gives:

  Could not find platform independent libraries <prefix>
  Could not find platform dependent libraries <exec_prefix>
  Consider setting $PYTHONHOME to <prefix>[:<exec_prefix>]
  Fatal Python error: Py_Initialize: Unable to get the locale encoding
  ImportError: No module named 'encodings'

  Current thread 0x00007f04862de740 (most recent call first):
  Aborted

  This can be solved by replacing line 22 of /usr/lib/command-not-found
  with:

  os.execv("/usr/bin/python3", [sys.argv[0]] + sys.argv)

  Searching for "os.execvp", it doesn't appear that the same error
  occurs for any other scripts in /usr/lib/. Any script using os.execvp
  with the correct permissions is a potential security vulnerability if
  the path is changed to contain a malicious script under the correct
  name. Fortunately this is not the case for command-not-found.

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