What are the Best Practices regarding error codes returned by a Console application?

Question

In c# you can return an integer to the underlying caller using Environment.Exit(n) (which can be tested, for instance, using the ERRORLEVEL variable from a DOS script).

Are there best practices regarding those codes?

I think 0 = no error... but are there numbers reserved? Can I use negative numbers? etc

Thanks!

Answer 1

Zero usually means that there were no errors. As for others, I don't think there is a reserved set. I would usually define what the different return codes of my application meant and document them.

DOS only handles a maximum of 256 possible return codes, but in reality I doubt you would ever use/need that many.

You can use negative values, but note that negative values do not necessarily mean anything different from positive values.

Answer 2

The most extensive use of return codes I've seen is in Robocopy. It may provide guidance for other apps. Robocopy uses return codes as flags:

0×10 Serious error. Robocopy did not copy any files. This is either a usage error or an error due to insufficient access privileges on the source or destination directories.

0×08 Some files or directories could not be copied (copy errors occurred and the retry limit was exceeded). Check these errors further.

0×04 Some Mismatched files or directories were detected. Examine the output log. Housekeeping is probably necessary.

0×02 Some Extra files or directories were detected. Examine the output log. Some housekeeping may be needed.

0×01 One or more files were copied successfully (that is, new files have arrived).

0×00 No errors occurred, and no copying was done. The source and destination directory trees are completely synchronized.