Installing Pylint for Python3 on Ubuntu

My understanding is that the latest release of Pylint (1.0.0 at the time of this writing) has support for Python 3, but I can't get it to work on 64-bit Ubuntu 13.04 with Python 3.3.

I followed the installation instructions on the PyPi site, and Pylint 1.0.0 seems to be installed successfully (pylint --version returns pylint 1.0.0), and works with Python 2.7 code, but it reports a syntax error when it sees nonlocal statements and such.

What gives? Are there special installation instructions for Pylint on Ubuntu?

Solution 1:

Python 2 and 3 are separate beasts. If you install a script into the site-packages of one version, you are not installing it into the other.

I'd install it through pip, but you'll need the right version of pip.

sudo apt-get install python3-pip
sudo pip-3.3 install pylint

This will replace your 2.7 version. We can confirm this by checking less $(which pylint):

#!/usr/bin/python3.3
# EASY-INSTALL-ENTRY-SCRIPT: 'pylint==1.0.0','console_scripts','pylint'
__requires__ = 'pylint==1.0.0'
import sys
from pkg_resources import load_entry_point

if __name__ == '__main__':
    sys.exit(
        load_entry_point('pylint==1.0.0', 'console_scripts', 'pylint')()
    )

Solution 2:

@sayth 's comment to the accepted answer was what drew me here -- I write both python 2 and python 3 scripts, and I want to be able to check either against the correct ruleset. installing pylint using pip3 install pylint writes a short script to /usr/local/bin which invokes the python3 interpreter, and seems, therefore to assume all files to be checked are python 3 scripts.

to work around this, I now have the following files:

~/bin/pylint2:

#!/usr/bin/python2
# EASY-INSTALL-ENTRY-SCRIPT: 'pylint','console_scripts','pylint'
__requires__ = 'pylint'
import sys
from pkg_resources import load_entry_point

if __name__ == '__main__':
    sys.exit(
        load_entry_point('pylint', 'console_scripts', 'pylint')()
    )

and ~/bin/pylint3:

#!/usr/bin/python3
# EASY-INSTALL-ENTRY-SCRIPT: 'pylint','console_scripts','pylint'
__requires__ = 'pylint'
import sys
from pkg_resources import load_entry_point

if __name__ == '__main__':
    sys.exit(
        load_entry_point('pylint', 'console_scripts', 'pylint')()
    )

and then, because I like to use pylint directly from Geany's "Build Commands" menu, and I can't specify different commands for python 2 and python 3 scripts, i also have ~/bin/pylint:

#!/bin/bash
if [[ $(head -n 1 "${@: -1}") == *python3* ]]
then
    # python3 file
    pylint3 "$@"
else
    pylint2 "$@"
fi

which dispatches the correct version by sniffing the shebang.

Not perfect, certainly, but functional and, perhaps, useful for others.

Solution 3:

The pylint ecosystem has changed since (after this question was asked), and there is now a separate pylint for python3. It can be installed with:

sudo apt install pylint3

Worked for me on Ubuntu 16.04.2 LTS

Solution 4:

As another method for running pylint on both Python 2 and 3, note that you can use Python's -m switch to run a module installed on the system in the current version of Python, so you can do

$ python2 -m pylint
$ python3 -m pylint

to explicitly select which one you want. You could make these into aliases or shell scripts if you wanted.

Solution 5:

The root of the problem is that pylint should come with entry point console scripts for /usr/local/bin/pylint2 and /usr/local/bin/pylint3. This should be considered a bug.

The following does not work; it still runs pylint2:

python3 -m pylint p3file.py

The following is what I have been using successfully:

python2 /usr/local/bin/pylint p2file.py
python3 /usr/local/bin/pylint p3file.py