|RTC(8)||Maintenance Commands and Procedures||RTC(8)|
rtc — provide all
real-time clock and UTC-lag management
The Real Time Clock (RTC) is the hardware device on x86 computers that maintains the date and time. The RTC is battery-powered, so that it keeps running when the computer is shut down. It can be set from the BIOS and also from the operating system running on the computer. The RTC has no setting for the time zone or for Daylight Saving Time (DST). It relies on the operating system for these facilities and for automatic changes between standard time and DST.
On x86 systems, the
rtc command reconciles
the difference in the way that time is established between UNIX and Windows
systems. The internal clock on UNIX systems utilizes Universal Coordinated
Time (UTC) while Windows systems usually expect the RTC to run in local
time, including DST changes.
rtc displays the
currently configured time zone string for the RTC. The currently configured
time zone string is based on what was last recorded by
rtc command is not normally run from a
shell prompt; it is generally invoked by the system. Commands such as
rdate(8), which are used to set the
time on a system, invoke
-c to ensure that daylight savings time (DST) is
corrected for properly.
If there is no RTC time zone or /etc/rtc_config file, this option will do nothing.
rtc. At boot time, the kernel reads the UTC lag from this file, and uses it to set the system time.
|January 31, 2018||OmniOS|