Commands APPEND/DPATH and FTYPE are also concerned by this; however
we do not implement them in our CMD.EXE yet.
These commands set the ERRORLEVEL differently, whether or not they are
run manually from the command-line/from a .BAT file, or from a .CMD file:
- From command-line/.BAT file, these commands set the ERRORLEVEL only if
an error occurs. So, if two commands are run consecutively and the first
one fails, the ERRORLEVEL will remain set even if the second command
succeeds.
- However, when being run from a .CMD file, these command will always
set the ERRORLEVEL. In the example case described above, the second
command that succeeds will reset the ERRORLEVEL to 0.
This behaviour is determined from the top-level batch/script file being
run. This means that, if a .BAT file is first started, then starts a
.CMD file, the commands will still behave the .BAT way; on the opposite,
if a .CMD file is first started, then starts a .BAT file, these commands
will still behave the .CMD way.
To implement this we introduce one global BATCH_TYPE enum variable that
is initialized to the corresponding batch/script file type when the
top-level script is loaded. It is reset to "none" when that script
terminates.
See https://ss64.com/nt/errorlevel.html for more details,
section "Old style .bat Batch files vs .cmd Batch scripts",
and https://groups.google.com/forum/#!msg/microsoft.public.win2000.cmdprompt.admin/XHeUq8oe2wk/LIEViGNmkK0J
(comment by Mark Zbikowski).
