On Mon, Mar 05, 2018 at 01:01:14PM +0100, Jan Kiszka wrote:
> Hi Andreas,
> 
> what is bg_setenv without any parameters supposed to do, and what does
> it actually - besides printing a suspicious "Environment update was
> successful."?
> 

Good point, thanks for asking.

If you specify no parameter, the program goes into
(write_mode), since you call bg_setenv and not bg_printenv.

Output to file is false, since no "-f" given.

auto_update is false, since no "-u" given.

part_specified is false, since no "-p" given.

This means, the program opens the latest environment and then calls
update_environment(env_new), where env_new is a handle to the latest
environment. (nothing new created at this point).

update_environment then processes an empty task list which does not
change the latest environment. It then recalculates the CRC32 again.

The program then stores the unmodified environment together with the
recalculated CRC32 back into the same place and exits.

Thus, bg_setenv without parameters performs a NOP on the current
environment data except the CRC and writes the values back again.

Thus, the question here is "what is the default behavior, a program
should have, if started without any parameter". 

I would say, in case of bg_setenv, the behavior is not offbeat, the
message is true and if the user has doubts about what to do, he should
use --help anyway. Per definition, all arguments are optional, therefore
it would be strange if the help page was printed as if the user missed
something, since optional arguments are not required per definition.

Andreas

> Jan
> 
> -- 
> Siemens AG, Corporate Technology, CT RDA IOT SES-DE
> Corporate Competence Center Embedded Linux

-- 
Andreas Reichel 
Dipl.-Phys. (Univ.) 
Software Consultant

[email protected] 
+49-174-3180074

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