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Name

rtc - provide all real-time clock and GMT-lag management

Synopsis

rtc [ -c ] [ -z zone-name ]

Availability

x86

SUNWcsu

Description

The /usr/sbin/rtc command is used to reconcile the difference in the way time is established between UNIX systems, which utilize Greenwich Mean Time (GMT), and MS-DOS systems, which utilize local time. When used with no arguments, rtc displays the currently configured time zone string which was recorded when rtc -z zone-name ws last run.

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.

Options

-c    
This option checks for DST and makes corrections if necessary. It is normally run once a day by a cron job.
If there is no RTC time zone or
/etc/rtc_config file, this option will do nothing.
-z zone-name
This option, which is normally run by the system at software installation time, is used to specify the time zone in which the RTC is to be maintained. It updates the configuration file /etc/rtc_config with the name of the specified zone and the current GMT lag for that zone. If there is an existing rtc_config file, this command will update it. If not, this command will create it.

Files

/usr/sbin/rtc
The command used to provide all real-time clock and GMT lag management.
/etc/rtc_config
The data file used to record the time zone and GMT lag. This file is completely managed by /usr/sbin/rtc, and it is read by the kernel.

See Also

date(1) , rdate(1M)

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