[FR] Add "standard" return codes to environmental exit/termination

[Kein]

What problem is this feature trying to solve?

Because parsing stdout text is pain when you use DD as cli tool and not a lib.

How would you like it to be solved?

By returning more or less "standardized" return codes for successful or failed operations.

Have you considered any alternative solutions

I stand corrected, parsing stdout is a MASSIVE pain.

Additional Information

Ackchyually, there are no standartized return codes between Linux/Windows, therefore...

Old, as Earth, and a meaningless argument, but her we go:
Sure, there aren't, but there is an overlap:

• WINDOWS has massive code catalog
• LINUX has only a few "reserved"

and because Linux is very lenient in this regard, and gives you pretty much unbound freedom to use any "unreserved" in anyway you want - there could be a free substitute for Linux return code responses (i.e. you can use window's 13 on Linux too).

Minimum effort mode:
Just return anything but 0 for any failed operation. Example:

1. User wants to download game/file
2. User initiates a download
3. DD either successfully downloads and writes a file (transient errors in-between are ignored) or validates existing cache and finds no changes/up-to-date
4. DD returns with 0
5. If DD fails to successfully execute #​4 (including even just failing at parsing cmd args) it returns with code > 0