Use exec to avoid an unnecessary subprocess being started by the Python wrapper and AppRun

[mxmlnkn]

I think this line:

python-appimage/python_appimage/data/python-wrapper.sh

Line 19 in a072354

{{ entrypoint }}

should be changed to:

exec {{ entrypoint }}

This would avoid another unnecessary subprocess being spawned, which would reduce resource usage and also unclutter the view in htop and other process manager tools.

Other files, such as entrypoint.sh and apprun.sh might also profit from this optimization.

Extracting python3.13.5-cp313-cp313-manylinux2014_x86_64.AppImage with --appimage-extract and executing squashfs-root/AppRun -c 'import time; time.sleep(60)' & inside a manylinux Docker and visualizing it with htop, yields:

This is unexpectedly one level more shallow than I thought. The reason for that seems to be that AppRun is a symlink to usr/bin/python3.13. Normally, after adding a custom entry point, the process tree would have one more level when exec is not used.

After adding the exec, it looks like this:

[mxmlnkn]

Turns out that one downside to starting python3 via exec is this: python/cpython#124241 (comment) . I guess in general, Python scripts should be written robustly enough to account for sys.executable being wrong, but for ease of use, it would be nice if it could be prevented on the AppImage side.

[mxmlnkn]

Turns out that this is not CPython's fault, but python-appimage has a hack that explicitly sets sys.executable to the AppImage:

python-appimage/python_appimage/data/_initappimage.py

Lines 9 to 16 in 984f77a

	command = env["APPIMAGE_COMMAND"]
	except KeyError:
	return
	if command and ("APPDIR" in env):
	command = os.path.abspath(command)
	sys.executable = command
	sys._base_executable = command

The problem was me copy-pasting code from the Python3 wrapper into my entrypoint.sh for various reasons. APPIMAGE_COMMAND should point to the python3 binary, not the AppImage.