1rtc(1M) System Administration Commands rtc(1M)
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6 rtc - provide all real-time clock and GMT-lag management
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9 /usr/sbin/rtc [-c] [-z zone-name]
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13 On x86 systems, the rtc command reconciles the difference in the way
14 that time is established between UNIX and MS-DOS systems. UNIX systems
15 utilize Greenwich Mean Time (GMT), while MS-DOS systems utilize local
16 time.
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19 Without arguments, rtc displays the currently configured time zone
20 string. The currently configured time zone string is based on what was
21 last recorded by rtc-z zone-name.
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24 The rtc command is not normally run from a shell prompt; it is gener‐
25 ally invoked by the system. Commands such as date(1) and rdate(1M),
26 which are used to set the time on a system, invoke /usr/sbin/rtc -c to
27 ensure that daylight savings time (DST) is corrected for properly.
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30 -c This option checks for DST and makes corrections if
31 necessary. It is normally run once a day by a cron job.
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33 If there is no RTC time zone or /etc/rtc_config file,
34 this option will do nothing.
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37 -z zone-name This option, which is normally run by the system at
38 software installation time, is used to specify the time
39 zone in which the RTC is to be maintained. It updates
40 the configuration file /etc/rtc_config with the name of
41 the specified zone and the current GMT lag for that
42 zone. If there is an existing rtc_config file, this
43 command will update it. If not, this command will cre‐
44 ate it.
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48 /etc/rtc_config The data file used to record the time zone and GMT
49 lag. This file is completely managed by
50 /usr/sbin/rtc, and it is read by the kernel.
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54 See attributes(5) for descriptions of the following attributes:
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59 ┌─────────────────────────────┬─────────────────────────────┐
60 │ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
61 ├─────────────────────────────┼─────────────────────────────┤
62 │Architecture │x86 │
63 ├─────────────────────────────┼─────────────────────────────┤
64 │Availability │SUNWcsu │
65 └─────────────────────────────┴─────────────────────────────┘
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68 date(1), rdate(1M), attributes(5)
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72SunOS 5.11 3 Oct 2003 rtc(1M)