Setting Up Linux for Python
Debian and Related Distros (Ubuntu, Linux Mint)
Python
For this program, you need Python3.6.* or 3.7.*
Debian distros already have the stable python2 and python3 releases preinstalled (Debian Wiki).
Try the following command:
$ python3
Python 3.6.3 (default, March 26 2017, 15:33:32)
[GCC 4.9.2 on linux]
>>>
I’m pretty sure that 18.4 (the most recent long term support release) has 3.6, if so, you are set.
That’s nice, which one is the default version? Just type python to see. It’s probably python2 still:
$ python
Python 2.7.9 (default, April 2 2015, 15:33:32)
[GCC 4.9.2 on linux2]
>>>
If you want to make python3.6 the default version then add the line alias python=python3 to your user’s /home/{user}/.bashrc file like so:
$ # before the change
$ python
Python 2.7.9 (default, April 2 2015, 15:33:32)
[GCC 4.9.2 on linux2]
>>>
$ echo "alias python=python3" >> ~/.bashrc
$ echo "alias pip=pip3" >> ~/.bashrc
$ echo "alias ipython=ipython3" >> ~/.bashrc
$ source ~/.bashrc
$ # after the change
$ python
Python 3.6.3 (default, March 26 2017, 15:33:32)
[GCC 4.9.2 on linux]
>>>
Alternatively, you can always remember to type python3 whenever you want Python.
Note: your version number may vary, but it needs to be 3.6.* or 3.7.*
You may not have pip and ipython installed yet, but you will as you follow the instructions below.
If you don’t have the version you want installed then use the package manager to find and install it:
$ # search the package manager for it
$ sudo apt-cache search python | grep '^python3.7\ -'
python3.7 - Interactive high-level object-oriented language (version 3.7)
$ # install it
$ sudo apt-get install python3.7
(If you cant find 3.7, try 3.6 instead)
Terminal
Every Linux box has a terminal emulator – find and use it.
pip
pip is the Python package installer.
Many Python packages are also available directly from your distro – but you’ll get the latest and greatest if you use pip to install it instead.
To get pip, the first option is to use your system package manager, something like:
$ sudo apt-get install python3-pip
If that doesn’t work, then try “ensure-pip”:
$ python3 -m ensurepip --upgrade
$ python3 -m ensurepip --upgrade
You can now use pip to install other packages. The first thing you may want to do is update pip itself:
$ python3 -m pip install --upgrade pip
Using pip:
To use pip to install a package, you invoke it with this command:
python3 -m pip install the_name_of_the_package
Where python3 is the command you use to invoke the Python you want to use (could be python3)
NOTE: You will frequently see advice to use pip like so:
$ pip install something_or_other
Which often works, but also can invoke the wrong version of pip. The above command:
$ python3 -m pip install something_or_other
calls Python, and tells it to run the pip module. It is exactly the same as calling pip directly, except that you are assured that you are getting the version of pip connected the version of python that you are running (in this case python3).
iPython
One extra package we are going to use in class is iPython:
$ sudo python3 -m pip install ipython
You should now be able to run iPython:
$ ipython3
Python 3.6.4 ()
Type "copyright", "credits" or "license" for more information.
IPython 2.0.0 -- An enhanced Interactive Python.
? -> Introduction and overview of IPython's features.
%quickref -> Quick reference.
help -> Python's own help system.
object? -> Details about 'object', use 'object??' for extra details.
git
Git is likely to be there on your system already, but if not:
$ sudo apt-get install git
Fedora and Red Hat Related Distros (CentOS)
Warning
CentOS is probably the most popular distro of these related flavors. However, getting Python3 on it can be a pain. You have been warned! (but there are lots of tutorials on the web – google “install python3 on CentOS”)
Python
Fedora distros already have the stable python2 and python3 releases preinstalled [2]. However, CentOS, the most popular distro only has the stable python2 release. Try the following commands:
[centos@ip-172-31-21-5 ~]$ python2
Python 2.7.5 (default, Jun 17 2014, 18:11:42)
[GCC 4.8.2 20140120 (Red Hat 4.8.2-16)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>>
[centos@ip-172-31-21-5 ~]$ python3
-bash: python3: command not found
Let’s install python3 using the package manager. Step one install “Software Collections” to help us:
$ sudo yum -y install scl-utils
Then go to the software collections listing and click on the Python collection version you want to install.
Probably this one:
https://www.softwarecollections.org/en/scls/rhscl/rh-python35/
Note, you also need to know which version of CentOS you are using (probably 6 or 7). For example, we care about python version 3.5 so let’s go the .rpm i want to install here:
$ # add this package to the rpm package manager
$ sudo rpm -Uvh https://www.softwarecollections.org/repos/rhscl/rh-python34/epel-7-x86_64/noarch/rhscl-rh-python35-epel-7-x86_64.noarch.rpm
$ # install the right python version
$ sudo yum install rh-python35
When you want to use python3 run this command:
[centos@ip-172-31-21-5 ~]$ scl enable rh-python35 bash
Terminal
Every Linux box has a terminal emulator – find and use it.
git
Git is likely to be there on your system already, but if not:
$ sudo yum install git
pip
pip is the Python package installer.
Many Python packages are also available directly from your distro – but you’ll get the latest and greatest if you use pip to install it instead.
In CentOS, if you used the above technique to install Python3, then it comes with pip. Try:
[centos@ip-172-31-21-5 ~]$ python -m pip -V
pip 8.1.2 from /opt/rh/rh-python35/root/usr/lib/python3.5/site-packages (python 3.5)
Using pip:
To use pip to install a package, you invoke it with this command:
python -m pip install the_name_of_the_package
Where python is the command you use to invoke the Python you want to use (could be python3)
NOTE: You will frequently see advice to use pip like so:
$ pip install something_or_other
Which often works, but also can invoke the wrong version of pip. The above command:
$ python -m pip install something_or_other
calls Python, and tells it to run the pip module. It is exactly the same as calling pip directly, except that you are assured that you are getting the version of pip connected the version of python that you are running.
iPython
One we are going to use in class is iPython:
$ sudo pip install ipython[all]
You should now be able to run iPython:
$ ipython3
Python 3.5.2 ()
Type "copyright", "credits" or "license" for more information.
IPython 5.1.0 -- An enhanced Interactive Python.
? -> Introduction and overview of IPython's features.
%quickref -> Quick reference.
help -> Python's own help system.
object? -> Details about 'object', use 'object??' for extra details.