Output from system startup ("rc") scripts is directed to /dev/msglog, which dispatches it appropriately.

See attributes(5) for descriptions of the following attributes:

syslogd(1M), syslog(3C), attributes(5), sysmsg(7D)

In the current version of Solaris, /dev/msglog is an alias for /dev/sysmsg. In future versions of Solaris, writes to /dev/msglog may be directed into a more general logging mechanism such as syslogd(1M).

syslog(3C) provides a more general logging mechanism than /dev/msglog and should be used in preference to /dev/msglog whenever possible.