Skip to content

Latest commit

 

History

History
79 lines (70 loc) · 2.44 KB

pythons.md

File metadata and controls

79 lines (70 loc) · 2.44 KB
Raw

pythons

Purpose

Show versions of Python interpreter

Syntax

Syntax: pythons [-h] [-a] [-d] [-v]

Options and arguments

Option Description Default
-a, --all Find all instances of executables in $PATH Only the first instance of each executable is reported
-d, --dumb Do not try to parse out version Logic is used to intelligently figure out a version. Usually this is the first token of the output that matches the regular expression \d\.
-v Enable verbose debugging Debugging is not enabled

Example

From my everyday Ubuntu workstation

$ pythons
Name     Location  Version
python   /usr/bin  2.7.17
python2  /usr/bin  2.7.17
python3  /usr/bin  3.6.9
$ pythons --dumb
Name     Location  Version
python   /usr/bin  Python 2.7.17
python2  /usr/bin  Python 2.7.17
python3  /usr/bin  Python 3.6.9
$

From a basic Amazon Linux 1 AWS instance

I spun up an instance from fresh and it didn't even have Python 3 so I installed it since most of my tools use it.

$ pythons
Name     Location  Version
python   /usr/bin  2.7.18
python2  /usr/bin  2.6.9
python3  /usr/bin  3.4.10
$

It's curious that /usr/bin/python is not the same as either /usr/bin/python2 or /usr/bin/python3 but it is what it is!!!

Inside virtualenv

I used virtualenv to set up an alternate Python:

$ virtualenv -p python3 venv
Already using interpreter /usr/bin/python3
Using base prefix '/usr'
New python executable in /media/mrbruno/tmp/venv/bin/python3
Also creating executable in /media/mrbruno/tmp/venv/bin/python
Installing setuptools, pkg_resources, pip, wheel...done.
$ . venv/bin/activate
(venv) $ pythons
Name     Location                     Version
python   /media/mrbruno/tmp/venv/bin  3.6.9
python2  /usr/bin                     2.7.17
python3  /media/mrbruno/tmp/venv/bin  3.6.9
(venv) $ pythons --all
Name     Location                     Version
python   /media/mrbruno/tmp/venv/bin  3.6.9
python   /usr/bin                     2.7.17
python2  /usr/bin                     2.7.17
python3  /media/mrbruno/tmp/venv/bin  3.6.9
python3  /usr/bin                     3.6.9
(venv) $

This shows you that virtualenv is basically prepending the venv directory to my $PATH in order to override the existing Python executables.

Notes

  • The following command is executed for each executable: 
    executable --version
  • See also the versions tool.