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8980 BIOS clock is sometimes one hour fast
Reviewed by: Toomas Soome <tsoome@me.com>
Reviewed by: C Fraire <cfraire@me.com>
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--- old/usr/src/man/man1m/rtc.1m.man.txt
+++ new/usr/src/man/man1m/rtc.1m.man.txt
1 1 RTC(1M) Maintenance Commands RTC(1M)
2 2
3 -
4 -
5 3 NAME
6 - rtc - provide all real-time clock and GMT-lag management
4 + rtc - provide all real-time clock and UTC-lag management
7 5
8 6 SYNOPSIS
9 - /usr/sbin/rtc [-c] [-z zone-name]
7 + rtc [-csuvw] [-z zone-name]
10 8
11 -
12 9 DESCRIPTION
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.
10 + The Real Time Clock (RTC) is the hardware device on x86 computers that
11 + maintains the date and time. The RTC is battery-powered, so that it
12 + keeps running when the computer is shut down. It can be set from the
13 + BIOS and also from the operating system running on the computer. The RTC
14 + has no setting for the time zone or for Daylight Saving Time (DST). It
15 + relies on the operating system for these facilities and for automatic
16 + changes between standard time and DST.
17 17
18 + On x86 systems, the rtc command reconciles the difference in the way that
19 + time is established between UNIX and Windows systems. The internal clock
20 + on UNIX systems utilizes Universal Coordinated Time (UTC) while Windows
21 + systems usually expect the RTC to run in local time, including DST
22 + changes.
18 23
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.
24 + Without arguments, rtc displays the currently configured time zone string
25 + for the RTC. The currently configured time zone string is based on what
26 + was last recorded by rtc -z zone-name.
22 27
28 + The rtc command is not normally run from a shell prompt; it is generally
29 + invoked by the system. Commands such as date(1) and rdate(1M), which are
30 + used to set the time on a system, invoke rtc -c to ensure that daylight
31 + savings time (DST) is corrected for properly.
23 32
24 - The rtc command is not normally run from a shell prompt; it is
25 - generally invoked by the system. Commands such as date(1) and
26 - rdate(1M), which are used to set the time on a system, invoke
27 - /usr/sbin/rtc -c to ensure that daylight savings time (DST) is
28 - corrected for properly.
29 -
30 33 OPTIONS
31 - -c
32 - This option checks for DST and makes corrections if
33 - necessary. It is normally run once a day by a cron job.
34 + -c This option checks for DST and makes corrections to the RTC if
35 + necessary. It is normally run once a day by a cron(1M) job.
34 36
35 - If there is no RTC time zone or /etc/rtc_config file,
36 - this option will do nothing.
37 + If there is no RTC time zone or /etc/rtc_config file, this option
38 + will do nothing.
37 39
40 + -s This option specifies that the RTC runs in local standard time
41 + all year round. It is incompatible with Windows, but is
42 + convenient if only one operating system is to be run on the
43 + computer. The cron(1M) command is not necessary, and should not
44 + be run.
38 45
39 - -z zone-name
40 - This option, which is normally run by the system at
41 - software installation time, is used to specify the time
42 - zone in which the RTC is to be maintained. It updates
43 - the configuration file /etc/rtc_config with the name of
44 - the specified zone and the current GMT lag for that
45 - zone. If there is an existing rtc_config file, this
46 - command will update it. If not, this command will
47 - create it.
46 + -u This option specifies that the RTC runs in UTC time. As a side
47 + effect, it sets the time zone in /etc/rtc_config to UTC. Windows
48 + can operate in UTC time, but requires a registry change to do so.
49 + The cron(1M) command is not necessary.
48 50
51 + -v This option specifies that the RTC tracks local time, including
52 + DST changes. This is the default. It accomodates Windows with
53 + no changes. The cron(1M) command is necessary to change the RTC
54 + when DST is in effect.
49 55
50 -FILES
51 - /etc/rtc_config
52 - The data file used to record the time zone and GMT
53 - lag. This file is completely managed by
54 - /usr/sbin/rtc, and it is read by the kernel.
56 + -w This option does nothing. It is present for compatibility with
57 + Solaris 11.
55 58
59 + -z zone-name
60 + This option, which is normally run by the system at software
61 + installation time, is used to specify the time zone in which the
62 + RTC is to be maintained. It updates the configuration file
63 + /etc/rtc_config with the name of the specified zone and the
64 + current UTC lag for that zone. If there is an existing
65 + /etc/rtc_config file, this command will update it. If not, this
66 + command will create it.
56 67
57 -ATTRIBUTES
58 - See attributes(5) for descriptions of the following attributes:
68 +FILES
69 + /etc/rtc_config The data file used to record the time zone and UTC lag.
70 + This file is completely managed by rtc. At boot time,
71 + the kernel reads the UTC lag from this file, and uses it
72 + to set the system time.
59 73
74 +ARCHITECTURE
75 + x86
60 76
61 -
62 -
63 - +---------------+-----------------+
64 - |ATTRIBUTE TYPE | ATTRIBUTE VALUE |
65 - +---------------+-----------------+
66 - |Architecture | x86 |
67 - +---------------+-----------------+
68 -
69 77 SEE ALSO
70 - date(1), rdate(1M), attributes(5)
78 + date(1), cron(1M), rdate(1M), attributes(5)
71 79
72 -
73 -
74 - October 3, 2003 RTC(1M)
80 +illumos January 31, 2018 illumos
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