Python On Linux ^HOT^

Note that if the version of the python3 package is not recent enoughfor you, there may be ways of installing more recent versions as well,depending on you distribution. For example installing the python3.9 packageon Fedora 32 to get Python 3.9. If you are a Fedora user, you might wantto read about multiple Python versions available in Fedora.

There are many ways to create a Python virtual environment after you have learnt how to install Python on Linux. Here we are going to see how to create a python virtual environment using the virtual environment package which comes with Python3.

Use the python --version terminal command to check whether Python is already installed and, if so, which version you have. If Python is not installed on your Linux system, or you want to install an updated version, follow the steps below.

Due to the way most Linux distributions are handling the Python 3migration, Linux users using the system Python without creating a virtualenvironment first should replace the python command in this tutorialwith python3 and the python -m pip command with python3 -m pip --user. Do notrun any of the commands in this tutorial with sudo: if you get apermissions error, come back to the section on creating virtual environments,set one up, and then continue with the tutorial as written.

Using your package manager (for example, Synaptic), download and install these packages: python3, python3-pip, python3-tk, python3-numpy, python3-pygame, python3-setuptools, and idle3. The package names may vary slightly across Linux distributions.

Note: It's likely that your package manager will offer all of the required packages, with the possible exception of python3-pygame. If your package manager doesn't offer python3-pygame, then first use your package manager to install all of the other required packages. Then open a terminal window and issue the python3 -m pip install -U pygame --user command. That command downloads and installs PyGame via pip, the Python-specific package manager.

Follow-up to the previous note: An alternative installation strategy is to use your package manager to install only the python-3 , python3-tk, idle3, and python3-pip packages, and then use pip to install the others by issuing these commands in a terminal window:

Issue the python3 setup.py install --user command. The computer copies the files defining the booksite modules to a directory where Python can find them, and writes status messages to your terminal window to indicate its progress.

Issue the python3 helloworld.py command to run your program. If the computer writes "Hello, World" to the terminal window, then the execution of your helloworld.py program was successful. If the computer instead writes error messages, then use your text editor to correct your program, and issue the python3 helloworld.py command again. Repeat until your program runs successfully. If your program runs successfully the first time you try, then intentionally introduce an error into your program, just so you get some experience with correcting errors.

In your file manager, double-click on the /home/yourusername/Downloads/introcs-python.zip file, thus creating the /home/yourusername/Downloads/introcs-python directory containing the booksite example programs.

If your Linux distribution came with Python, you might need to install the Python developer package to get the headers and libraries required to compile extensions and install the EB CLI. Use your package manager to install the developer package (typically named python-dev or python-devel).

will be to install Python 2.7 with the Python 2Miniconda and to install Python 3.8 with the Python3 Miniconda. You can override the default byexplicitly setting python=2 or python=3. Italso determines the default value of CONDA_PYwhen using conda build.

The Debian/Ubuntu package is split in three different packages calledpython3-sklearn (python modules), python3-sklearn-lib (low-levelimplementations and bindings), python3-sklearn-doc (documentation).Only the Python 3 version is available in the Debian Buster (the more recentDebian distribution).Packages can be installed using apt-get:

On EL7, EL8, and SUSE: A python3-protobuf RPM package is not available for Python 3.8 on these platforms, so the dependency is not part of the RPM specification; instead it must be manually installed with the likes of pip install protobuf. This is required as of v8.0.29.

Note: The commands are the same for all operating systems except for Fedora. If you are working on this OS, the command to install NumPy with Python 3 is: python3 -m pip install numpy.

Oracle Linux 9 includes the concept of Application Streams, where multiple versions of user-space components can be delivered and updated more frequently than the core operating system packages in RPM format or groups of related RPMs called Modules. The initial release of Oracle Linux 9 includes Python 3.9 as the full lifecycle Python release; further python release may be released as AppStream Modules in the future.

cx_Oracle RPM built to work with SCL Python versions are named according to the following format: rh-python-python-cx_Oracle For example, to install the matching cx_Oracle RPM for Python 3.6 from SCL:

Now, what happens if there's a shebang line (#!/usr/bin/python or #!/usr/bin/env python) at the top of the Python script? Well, since # is a comment line in Python, the Python interpreter just ignores it. This is one reason why most scripting languages used in the Unix/Linux world use # to start comment lines.

The first thing to note is that Unix/Linux, unlike Windows, isn't trying to "open" Python scripts using a particular program, at least conceptually; the OS knows that the script is something that can be executed because of something called the "execute bit" (which is outside the scope of this answer). So, if you accidentally type #!/usr/bin/pthon instead of #!/usr/bin/python, you'll get an error message that includes this text:

The line you've indicated is used to tell the computer what program / interpreter to use when running the file/script directly, and any arguments that should be passed to that program when the script runs. This is not, however, a requirement of Python, it's a requirement of the linux kernel/system if you intend to run the script directly (and not pass it to Python by the below syntax).

It is not needed if you are going to execute python script.py or similar. It is only needed if you intend to run the script/file directly, without also providing the interpreter to use (such as python).

Without that line at the beginning, and assuming you have set the file/script to be executable, and assuming you're working with a Python script, you would have to run python filename.py or similar if you did not have the #!/usr/bin/python line. (For a Bash script, you would have to do bash script.sh, or similar for other scripts/languages, such as Perl, Ruby, etc.)

Technically, it doesn't require it. It requires a path to the environment where your script executes. Your future scripts would be better off to include /usr/bin/env then, specify python. This grantees that your script runs in the python environment no matter where python is installed. You want to do this for compatibility reasons, you cannot be sure the next person you share your code with will have python installed in usr/bin/python, or that they will have permissions to those system files.

Python interactive mode allows the user to type and run Python codes directly, which does not require the shebang line. To run the interactive mode, open a Terminal and type python for Python 2.X or python3 for Python 3.X.

It means that when that file is executed your computer knows to execute it with the program /usr/bin/python, that's how you tell it apart from another language, such as bash where you would do #!/bin/bash. This is so that you can simply run:

If you have several versions of Python installed, /usr/bin/env will ensure the interpreter used is the first one on your environment's $PATH. The alternative would be to hardcode something like #!/usr/bin/python;

If you run the command python3 and you get the error command not found, then that means the system cannot find an executable named python3 in $PYTHONHOME/bin. A symlink is required for the OML4Py server installation components. So, in that case, you need to create a symbolic link in your PREFIX/bin directory to link to your python3.9 executable as described in Step 6.

If you're developing, it's better to do it in editable mode. The reason whyis that pytest's test discovery only works for Matplotlibif installation is done this way. Also, editable mode allows your code changesto be instantly propagated to your library code without reinstalling (thoughyou will have to restart your python process / kernel):

The first thing to try is a clean install and see ifthat helps. If not, the best way to test your install is by running a script,rather than working interactively from a python shell or an integrateddevelopment environment such as IDLE which add additionalcomplexities. Open up a UNIX shell or a DOS command prompt and run, forexample:

Apple ships OSX with its own Python, in /usr/bin/python, and its own copyof Matplotlib. Unfortunately, the way Apple currently installs its own copiesof NumPy, Scipy and Matplotlib means that these packages are difficult toupgrade (see system python packages). For that reason we strongly suggestthat you install a fresh version of Python and use that as the basis forinstalling libraries such as NumPy and Matplotlib. One convenient way toinstall Matplotlib with other useful Python software is to use the AnacondaPython scientific software collection, which includes Python itself and awide range of libraries; if you need a library that is not available from thecollection, you can install it yourself using standard methods such as pip.See the Anaconda web page for installation support. 2b1af7f3a8