[Logcheck-devel] Bug#289801: Logtail should output error messages to stderr, not stdout

[Peter Hawkins]

Package: logtail
Version: 1.2.33
Severity: normal

Hi...

Logtail should not output error messages to standard output, since this 
violates the principle of least surprise.

In particular, my application was broken by the semantics of logtail changing 
in version 1.2.21 (when you added switches for the default arguments to 
logtail). I think this was a bad move -- you broke an interface used by other 
people for no immediately apparent reason. logtail is _not_ only used by 
logcheck! Please consider other users of logtail next time you change 
something.

That notwithstanding, since logtail prints its error messages to standard 
output, the error message about the incorrect argument format is lost. One 
would expect the normal usage of logtail would have been something like:
logtail logfile offsetfile | some_program

With the new version of logtail, this produces an error message to standard 
output, which is then sent to 'some_program'. I would claim that the correct 
behaviour is to send the message to standard error, so logtail is not 
silently broken by installing logtail from sarge.

=)
Peter