Ubuntu 20.04 without python-as-python3 apt package errors No such file or directory: 'python'

[christopherpickering]

• I am on the latest Poetry version.
• I have searched the issues of this repo and believe that this is not a duplicate.
• If an exception occurs when executing a command, I executed it again in debug mode (-vvv option).

• OS version and name: Ubuntu 20.04
• Poetry version: 1.1.8

Issue

Attempting to run any poetry commands results in

Installing dependencies

  FileNotFoundError

  [Errno 2] No such file or directory: 'python'

  at /usr/lib/python3.8/subprocess.py:1704 in _execute_child
      1700│                     else:
      1701│                         err_filename = orig_executable
      1702│                     if errno_num != 0:
      1703│                         err_msg = os.strerror(errno_num)
    → 1704│                     raise child_exception_type(errno_num, err_msg, err_filename)
      1705│                 raise child_exception_type(err_msg)
      1706│ 
      1707│ 
      1708│         def _handle_exitstatus(self, sts, _WIFSIGNALED=os.WIFSIGNALED,

  FileNotFoundError

  [Errno 2] No such file or directory: 'python'

  at /usr/lib/python3.8/subprocess.py:1704 in _execute_child
      1700│                     else:
      1701│                         err_filename = orig_executable
      1702│                     if errno_num != 0:
      1703│                         err_msg = os.strerror(errno_num)
    → 1704│                     raise child_exception_type(errno_num, err_msg, err_filename)
      1705│                 raise child_exception_type(err_msg)
      1706│ 
      1707│ 
      1708│         def _handle_exitstatus(self, sts, _WIFSIGNALED=os.WIFSIGNALED,

  FileNotFoundError

  [Errno 2] No such file or directory: 'python'

  at /usr/lib/python3.8/subprocess.py:1704 in _execute_child
      1700│                     else:
      1701│                         err_filename = orig_executable
      1702│                     if errno_num != 0:
      1703│                         err_msg = os.strerror(errno_num)
    → 1704│                     raise child_exception_type(errno_num, err_msg, err_filename)
      1705│                 raise child_exception_type(err_msg)
      1706│ 
      1707│ 
      1708│         def _handle_exitstatus(self, sts, _WIFSIGNALED=os.WIFSIGNALED,
Env Info:

  FileNotFoundError

  [Errno 2] No such file or directory: 'python'

  at /usr/lib/python3.8/subprocess.py:1704 in _execute_child
      1700│                     else:
      1701│                         err_filename = orig_executable
      1702│                     if errno_num != 0:
      1703│                         err_msg = os.strerror(errno_num)
    → 1704│                     raise child_exception_type(errno_num, err_msg, err_filename)
      1705│                 raise child_exception_type(err_msg)
      1706│ 
      1707│ 
      1708│         def _handle_exitstatus(self, sts, _WIFSIGNALED=os.WIFSIGNALED,

In ubuntu 20.04 there is not "python" command, only "python3". If I install sudo apt-get install python-is-python3, then poetry starts to work again.

It would be nice if poetry picked python3 if there is no python instead of failing. There is a python installed.

[finswimmer]

Hello @christopherpickering,

how did you install poetry?

fin swimmer

[christopherpickering]

Hi @finswimmer, heres how:

curl -sSL https://raw.githubusercontent.com/python-poetry/poetry/master/install-poetry.py | $(which python3) -

It installs fine.

[finswimmer]

Thanks for your response! I'm able to reproduce it. It seems to be due to a change in poetry 1.1.8. I have no problems with 1.1.7. I guess #4414 is somehow related.

[luisacabs-out]

I have this issue as well

[SumGR]

I can confirm this too in Alpine 3.13.5. I didn't lock poetry to a specific version in our build pipeline and started seeing the following error:

+ poetry install

  FileNotFoundError

  [Errno 2] No such file or directory: 'python'

  at /usr/lib/python3.8/subprocess.py:1704 in _execute_child
      1700│                     else:
      1701│                         err_filename = orig_executable
      1702│                     if errno_num != 0:
      1703│                         err_msg = os.strerror(errno_num)
    → 1704│                     raise child_exception_type(errno_num, err_msg, err_filename)
      1705│                 raise child_exception_type(err_msg)
      1706│ 
      1707│ 
      1708│         def _handle_exitstatus(self, sts, _WIFSIGNALED=os.WIFSIGNALED,

Poetry is installed into the Alpine image using pip3. Pinning it using pip3 install poetry==1.1.7 resolved the issue. Alpine (as well as the Ubuntu version listed above) do not create a symbolic link from python->python3.x and it seems 1.1.8 somehow introduced spawning the interpreter by that name in a subprocess call.

[wouterdb]

Same problem on Centos 8 since the release of 1.1.8

[EthanC]

Same issue on DietPi v7.5 (Debian Bullseye), adding an alias for python to python3 does not resolve either.

[jd-solanki]

Same issue on my Linux mint 20

[nicolashainaux]

The same problem shows up in older Ubuntu 18.04 (bionic), but there's no python-is-python3 package as workaround on bionic. Also things like alias python="python3.6" do not fix the issue.

[lorenzznerol]

I think I have the same on an Alpine docker container with Python 3.6 and Poetry 1.1.8 installed:

$ poetry add pandas

  FileNotFoundError

  [Errno 2] No such file or directory: 'python': 'python'

  at /usr/lib/python3.6/subprocess.py:1364 in _execute_child
      1360│                     if errno_num != 0:
      1361│                         err_msg = os.strerror(errno_num)
      1362│                         if errno_num == errno.ENOENT:
      1363│                             err_msg += ': ' + repr(err_filename)
    → 1364│                     raise child_exception_type(errno_num, err_msg, err_filename)
      1365│                 raise child_exception_type(err_msg)
      1366│
      1367│
      1368│         def _handle_exitstatus(self, sts, _WIFSIGNALED=os.WIFSIGNALED,

Installing Poetry 1.1.7 instead leads to:

$ poetry add pandas
Creating virtualenv pandas-il7asoJj-py3.6 in /root/.cache/pypoetry/virtualenvs
Using version ^1.3.2 for pandas

Updating dependencies
Resolving dependencies... (0.0s)

  AssertionError



  at /usr/lib/python3.6/site-packages/poetry/mixology/incompatibility.py:111 in __str__
      107│         )
      108│
      109│     def __str__(self):
      110│         if isinstance(self._cause, DependencyCause):
    → 111│             assert len(self._terms) == 2
      112│
      113│             depender = self._terms[0]
      114│             dependee = self._terms[1]
      115│             assert depender.is_positive()

Not knowing what the latter is about, but the python error has obviously gone when using Poetry 1.1.7 instead of Poetry 1.1.8.