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.