RTC(1M)RTC(1M)NAMErtc - provide all real-time clock and GMT-lag management
SYNOPSIS
/usr/sbin/rtc [-c] [-z zone-name]
DESCRIPTION
On x86 systems, 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 gener‐
ally 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 cre‐
ate it.
FILES
/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.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌───────────────┬─────────────────┐
│ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├───────────────┼─────────────────┤
│Architecture │ x86 │
└───────────────┴─────────────────┘
SEE ALSOdate(1), rdate(1M), attributes(5)
Oct 3, 2003 RTC(1M)
