Out of home folder .pyc files? - python

If I place my project in /usr/bin/
will my python interpreter generate bytecode? If so where does it put them as the files do not have write permission in that folder. Does it cache them in a temp file?
If not, is there a performance loss for me putting the project there?
I have packaged this up as a .deb file that is installed from my Ubuntu ppa, so the obvious place to install the project is in /usr/bin/
but if I don't generate byte code by putting it there what should I do? Can I give the project write permission if it installs on another persons machine? that would seem to be a security risk.
There are surely lots of python projects installed in Ubuntu ( and obviously other distros ) how do they deal with this?
Thanks

Regarding the script in /usr/bin, if you execute your script as a user that doesn't have permissions to write in /usr/bin, then the .pyc files won't be created and, as far as I know, there isn't any other caching mechanism.
This means that your file will be byte compiled by the interpreter every time so, yes, there will be a performance loss. However, probably that loss it's not noticeable. Note that when a source file is updated, the compiled file is updated automatically without the user noticing it (at least most of the times).
What I've seen is the common practice in Ubuntu is to use small scripts in /usr/bin without even the .py extension. Those scripts are byte compiled very fast, so you don't need to worry about that. They just import a library and call some kind of library.main.Application().run() method and that's all.
Note that the library is installed in a different path and that all library files are byte compiled for different python versions. If that's not the case in your package, then you have to review you setup.py and your debian files since that's not the way it should be.

.pyc/.pyo files are not generated for scripts that are run directly. Python modules placed where Python modules are normally expected and packaged up have the .pyc/.pyo files generated at either build time or install time, and so aren't the end user's problem.

Related

any known way to create a device-to-device portable self-contained python runtime?

I want to distribute a python program on, say, Windows and/or Mac, but I don't want to give the user the headache of ensuring there is an appropriate python runtime installed on their machine. And i don't want to interfere with their machine's configuration by, let's say, requesting root privileges and installing a system-wide python runtime on their system that suits my program specifically because it's too invasive and might cause compatibility collisions with other installed versions of the runtime.
I would much rather have a self-contained executable that could be, for example, stored on a USB flash-drive, inserted into the system, and then maybe with a stepping-stone binary executable that just invokes the device-portable runtime on a python script that I provide, I could then run the program as if it were a self-contained binary executable (with only standard-library dependencies).
A link to this binary executable could be published into main-menu program lists, docks, or desktops. And it could be invoked by shell scripts or other executed-by-proxy mechanisms. Such a no-install/self-contained python program could potentially be a first-class user-invokable application. This is what I want to achieve.
I googled around for projects that provided a device-portable/mobile python installation and so far I've only found portablepython.com. Unfortunately it says the project is discontinued and no download link for the project is provided. it listed some similar projects but they all seemed defunkt or with a very different focus.
Does anyone know of an active project that is or includes such an independent/portable/mobile/no-install distribution for python?
or is there some way i could configure python's build system to build a noinstall-friendly product?
any ideas welcome. thanks for your input!
After more searching I found that Python.org publishes its own standalone-python distribution called the embeddable zip file.
This is exactly what I was searching for. It's a basic python standalone runtime that requires relatively few megabytes of storage.
I started with this embeddable distro and then cajoled a standalone copy of pip to work with it. Problem solved.
Improving upon #oreus2020's answer, you can download the embeddable zip file from here. Then, unzip the compressed file to a folder of your choice. Go to the root of your install and find python._pth file and open it in a text editor. Remove the "#" before import site(This file is the one which manages the environment of the portable install. If you want anything to be recognized by the portable python interpreter, just throw the path in here and that's it!). If you want pip, go to this page and save it in the root of your portable install and run it using the portable python interpreter like ./python get-pip.py from a commandline opened at the root of your install. Pip installed! To use the pip, do ./python -m pip <commands> from the commandline opened at the root of your install and then open the python._pth file and insert the following below the "." ./Lib/site-packages ./Scripts. Voila, you got yourself a python portable install!
My python._pth file looks like:
python39.zip
.
# Uncomment to run site.main() automatically
./Repo
./Repo/Code
./Repo/Code/cogs
./Lib/site-packages
./Scripts
import site
If you are still wondering, here is the link to the one I made for myself.
P.S. Pardon my bad English

How to ditribute my Unix application?

I created a command-line python tool for Unix systems.
I want my script to be executed from anywhere just like any Unix command. One solution is to make my script executable and move it to /usr/bin.
But the script works with external files, and I guess moving all these files with my script in /usr/bin is a bad habit, as it will be hard to delete them one by one in the future.
Where should I put the directory of my application ? How to add the main script to the PATH, to execute it from anywhere ?
I would like then to create a package that could move my files in the right place, and delete them in the case the user wants to uninstall my application.
I don't know how to do this.
Thank you.
There are many way of distributing a Linux application.
It will depend on the distribution you are using, since they do not all use the same package manager. For example, you would create a .deb package for Debian, Ubuntu and there derivatives, an Arch package for Archlinux, etc...
You could then share the package with anyone to let them install your tool.
However, since your tool is in written in Python, you can also make a python package. You could then upload it to the Python Package Index to let anyone install it using python's pip package manager.
To create a python package, you will need to create a file called setup.py, and, from it, to call the setup method from the setuptool packages.
You will probably want to read the python documentation about writing such a script: https://setuptools.readthedocs.io/en/latest/setuptools.html
You may especially be interested by this sections:
Including Data Files
Automatic Script Creation
If you do things correctly, setuptools will take care of installing your script and its files somewhere in the PATH so it can be executed from the command line.
You should use setuptools to distribute your application, creating a setup.py file to configure its setup and installation.
Binaries can be delivered using the console_scripts option, while data files can be delivered using either package_data.

Why is python27.dll not part of python installed folder but in Windows system folder

As described in: http://bugs.python.org/issue22139, the python27.dll is installed in the windows systems (in my case C:\Windows\Systems32) folder.
But I would like to know why? Why is it not installed next to the python.exe, for example in C:\Python27\?
Reason I ask: I've made a mercurial hook in python that our developers need to use to check if the commit message is valid. It checks a.o. for a valid JIRA issue number. To prevent all our developers to install python themselves and install the required modules manually (a lot of work and errorprone), I zipped the python installation and asked the developers to unzip it locally. But they can't run it, because the python27.dll is missing, or worse, they already have another minor version of python installed, and the hook will fail due to the wrong python27.dll used. Confusing.
If I just add the python27.dll (the correct version) to the zip file, it all seems to work great. So, why is it not installed in that location in the first place? What is the advantage of installing it in C:\Windows\System32?
Hope someone can explain this to me!
Thanks in advance,
Tallandtree.
I use the Anaconda Python distribution from http://continuum.io. They put python27.dll into c:\anaconda right next to its python.exe. This distribution is also superior in that you can have multiple python environments with precisely the packages you need and switch between them easily (http://conda.pydata.org/docs/using/envs.html). You can also get the package list of one of your environments and distribute it to others.
I recommend this Python distribution over the one from python.org and Enthought, because of this issue.
.dlls are quite windows-specific files. I imagine you will have shared object (.so) files for LINUX/UNIX-specific Python stuff? You said your developer's couldn't run it, because they didn't have the correct DLL (i.e. the one relevant to their Python installation).
Also, the advantage of installing it to System32 is that it's in the default PATH. Additionally, if any other application is internally using Python and require access to the .dll file, and also NOT reference your Python directory, they will probably be looking for a location that "Actually" exists (I wanted to say guaranteed to exist, but......never mind). That location would be `C:/windows/Systems32'.
I found it to work just fine to put python27.dll in the Python directory (c:\Python27 or wherever). As long as it's in the PATH, it seems to work. I did this for a "relocatable" installation of Python. I can copy the installation directory to a Windows machine that has no Python installed, set the PATH to include that directory, and run Python, including all the libraries I had installed with pip install on the original machine.

Python compile all modules into a single python file

I am writing a program in python to be sent to other people, who are running the same python version, however these some 3rd party modules that need to be installed to use it.
Is there a way to compile into a .pyc (I only say pyc because its a python compiled file) that has the all the dependant modules inside it as well?
So they can run the programme without needing to install the modules separately?
Edit:
Sorry if it wasnt clear, but I am aware of things such as cx_freeze etc but what im trying to is just a single python file.
So they can just type "python myapp.py" and then it will run. No installation of anything. As if all the module codes are in my .py file.
If you are on python 2.3 or later and your dependencies are pure python:
If you don't want to go the setuptools or distutiles routes, you can provide a zip file with the pycs for your code and all of its dependencies. You will have to do a little work to make any complex pathing inside the zip file available (if the dependencies are just lying around at the root of the zip this is not necessary. Then just add the zip location to your path and it should work just as if the dependencies files has been installed.
If your dependencies include .pyds or other binary dependencies you'll probably have to fall back on distutils.
You can simply include .pyc files for the libraries required, but no - .pyc cannot work as a container for multiple files (unless you will collect all the source into one .py file and then compile it).
It sounds like what you're after is the ability for your end users to run one command, e.g. install my_custom_package_and_all_required_dependencies, and have it assemble everything it needs.
This is a perfect use case for distutils, with which you can make manifests for your own code that link out to external dependencies. If your 3rd party modules are available publicly in a standard format (they should be, and if they're not, it's pretty easy to package them yourself), then this approach has the benefit of allowing you to very easily change what versions of 3rd party libraries your code runs against (see this section of the above linked doc). If you're dead set on packaging others' code with your own, you can always include the required files in the .egg you create with distutils.
Two options:
build a package that will install the dependencies for them (I don't recommend this if the only dependencies are python packages that are installed with pip)
Use virtual environments. You use an existing python on their system but python modules are installed into the virtualenv.
or I suppose you could just punt, and create a shell script that installs them, and tell them to run it once before they run your stuff.

Include python library with program distribution

Is there a way to distribute a python library with an application, so that it can be run with out any installation? The app is primarily going to be used in a computer lab, where users do not have permission to install global libraries. Ideally, users would simply be able to unzip a folder and run the app. The following can be assumed:
The python interpreter is present
Linux operating system
The specific library I need is matplotlib, but I would like to find a generic solution. I've looked at programs like PyInstaller, but they create very large programs that are slow to start. They also include a python interpreter, which is unnecessary.
Firstly, p2exe is Windows only.
In principle you can put all of you libraries into the ZIP file so they get expanded in place with thie application. At most you may need to adjust the PYTHONPATH variable to point at the lib's location.
There is no technical difference between modules installed on the path and in the system's python installation.
Have you looked at cxfreeze?

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