The rtc command reconciles the difference in the way that time is established between UNIX and MS-DOS systems. UNIX systems utilize Greenwich Mean Time (GMT),
while MS-DOS systems utilize local time.
Without arguments, rtc displays the currently configured time zone string. The currently configured time zone string is based on what was last recorded by rtc-z zone-name.
The rtc command is not normally run from a shell prompt; it is generally invoked by the system. Commands such as date(1) and rdate(1M),
which are used to set the time on a system, invoke /usr/sbin/rtc -c to ensure that daylight savings time (DST) is corrected for properly.