I seen the some difference when I execute the .py file. I have observed two cases,
1) when I run the .py file using the python mypython.py
I got the result. But .pyc file not created in my folder.
2) when I run the .py file using the python -c "import mypython"
I got the same result. But .pyc file was created in my folder.
My question is why first case not created .pyc file ?
Import is generally used when you need to use the contents of a file in another script or program, see What does python file extensions, .pyc .pyd .pyo stand for?. So to more specifically answer the question, the .pyc is created to ease access to the contents of the file in the future and is only created when the import command is used.
Python saves the precompiled .pyc file only for imported modules, not for the main script you're running.
Running a program as main or importing it as a module is not the exact same thing, but very similar because in a module everything that is at top level is executed at import time.
Note that for main program the source code is completely parsed and compiled too (so for example if you have a syntax error in last line nothing will be executed). The difference is only that the result of compilation is not saved back to disk.
Related
I Created a Program That Has 2 .py files.
I Want To Make The Program a .exe file, I do it using cx_Freeze.
My Problem Is That I Convert The main.py To .exe but The Second Python File Is Still a .py File.
I Don't Want It Be a .py Because If It Is The User Can See The Code.
If I Also Convert The Second Python File The Program Doesn't Work Because I import The Python File In The Main File.
Any Suggestions?
(I Don't Want To Copy The Second Python File To The Main Python File)
You are chasing the wrong rabbit here. The various tools that generate executable files from Python code are not compilers. They are just tools that embed a Python interpretor with py (or pyc) files to allow users to use the program without a prior Python installation.
Said differently you should not use them to hide your code (except from people not knowing a lot of Python): a pyc does not contain text code but according to the answers to Is it possible to decompile a compiled .pyc file into a .py file? , tools exists that convert back a pyc file into a py file (of course except the comments).
IMHO, you should better google for python obfuscate to find tools dedicated to obfuscation, what neither cx-freeze nor pyinstaller are.
BTW while there are appropriate use cases for obfuscation you should be aware that a determinate attacker can always circumvent it. The reason why the real protection for intellectual property is law and not technics...
I'm not sure how two or more .py files can be converted to .exe.
But in python the easiest way to convert to .exe is a module named pyinstaller .
You can install it using command pip install pyinstaller can get it . After just go to the directory where your project files are and open command prompt in that directory and execute pyinstaller file_name
I am creating a python script that should modify itself and be portable.
I can achieve each one of those goals separately, but not together.
I use cx_freeze or pyinstaller to pack my .py to exe, so it's portable; but then I have a lot of .pyc compiled files and I can't edit my .py file from the software itself.
Is there a way to keep a script portable and lightweight (so a 70mb portable python environment is not an option) but still editable?
The idea is to have a sort of exe "interpreter" like python.exe but with all the libraries linked, as pyinstaller allows, that runs the .py file, so the .py script can edit itself or be edited by other scripts and still be executed with the interpreter.
First define your main script (cannot be changed) main_script.py. In a subfolder (e.g. named data) create patch_script.py
main_script.py:
import sys
sys.path.append('./data')
import patch_script
inside the subfolder:
data\patch_script.py:
print('This is the original file')
In the root folder create a spec file e.g. by running pyinstaller main_script.py.
Inside the spec file, add the patch script as a data resource:
...
datas=[('./data/patch_script.py', 'data' ) ],
...
Run pyinstaller main_sript.spec. Execute the exe file, it should print
This is the original file
Edit the patch script to e.g. say:
print('This is the patched file')
Rerun the exe file, it should print
This is the patched file
Note: As this is a PoC, this works but is prone to security issues, as the python file inside the data directory can be used for injection of arbitrary code (which you don't have any control of). You might want to consider using proper packages and update scripts as used by PIP etc.
When a .py file is being edited in IDLE, it can be renamed or deleted while still being able to run, but in other file types such as word files this is not allowed. You can even create a script using the os module to delete itself and then do an action, and that action still works. How is this possible?
When you run python scripts you scripts were loaded into memory. So you can edit your script files.
I can't find any info on this but when I try and create a zip archive in Python it creates a .pyc instead.
#!/Python27/python
import zipfile
z = zipfile.ZipFile('test.zip', 'w')
z.write('README.txt')
z.close()
This is the result of running the script.
The script you're running (or some other script you have) is actually called zipfile.py, and so Python is actually first looking in the folder your script is in to find a module called zipfile. When it finds this script, it imports that instead of the actual module.
Any time a script is imported to another Python file, Python automatically creates a compiled .pyc file resulting in that zipfile.pyc. If you rename your file to something more specific (and also fix your typo) you should be able to avoid this problem.
A rookie question here:
I have a PY code and compiled it to create a .pyc. I would want to use this pyc file instead of PY.
I am running the PY file using external program. When the PY exists in the folder everything works perfect. However when I remove the PY file and simply use the pyc I get error:
IOError: [Errno 2] No such file or directory: 'E:/data/test/tech.py'
Whereas I have a tech.pyc lying around in the same folder.Any ideas what could be the issue here?
Normally, python is not compiled. The .pyc files are only a performance optimization that improve loading times.
Python is looking for the .py file because it always checks that first. If a .pyc file is newer than its corresponding .py file, it will then use the .pyc file. If the .py file is newer it will create a new .pyc file.