In a nutshell it's just a sys->fprint(sys->fildes(2), "...") implemented as separate module, which you have to load, init, and setup before calling that fprint. And here is features you get in return:

• 5 log levels: ERR, WARN, NOTICE, INFO, DEBUG
• default log level set from environment variable $loglevel
• prefix output messages with:
• application name (optional)
• module/subsystem name (optional)
• log level
• log messages from 3rd-party module (which also use this logger) will include your application name when that module was loaded by your application

To install make directory with this module available in /opt/powerman/logger/, for ex.:

# hg clone https://inferno-contrib-logger.googlecode.com/hg/ $INFERNO_ROOT/opt/powerman/logger

or in user home directory:

$ hg clone https://inferno-contrib-logger.googlecode.com/hg/ $INFERNO_USER_HOME/opt/powerman/logger
$ emu
; bind opt /opt