There is some flexibility in the colorSpec logging level and format.
Logging output goes to stderr(), just like the message stream;
but see sink() (and the pitfalls of using it).
Arguments
Logging Options
colorSpec.loglevel
The levels are:
"FATAL", "ERROR", "WARN", "INFO", "DEBUG", and "TRACE" - the usual ones from Log4j.
The initial level is "WARN".
A "FATAL" event usually means an internal package error.
When setting colorSpec.loglevel an initial letter is sufficient.
colorSpec.logformat
The format is given by a string with standard Log4jconversion specifications:
%t
the date/time of the logging event.
%t can be followed by standard strftime specs in braces; see example.
%l
the level of the logging event
%n
namespace where event occurred
%f
function where event occurred
%m
the message itself
colorSpec.stoponerror
If the this option is TRUE (the default),
a log event with level "ERROR" stops execution;
otherwise, execution keeps going.
For interactive use, TRUE is probably better.
For long batch jobs, FALSE might be appropriate,
since then a single error may not force a complete repeat.
A "FATAL" event always stops execution.