Setting the System Time - Revision history

Bserrano at 20:38, 19 March 2014

2014-03-19T20:38:13Z

Bserrano at 20:36, 19 March 2014

2014-03-19T20:36:56Z

Bserrano at 21:35, 4 March 2014

2014-03-04T21:35:39Z

Kyoungmeyer: fmbox to imbox

2013-12-31T21:05:44Z

fmbox to imbox

Mdean: Fixed tag.

2013-12-20T02:51:26Z

Fixed tag.

Mdean: Approved for Complete.

2013-11-18T04:59:55Z

Approved for Complete.

Show changes

Mdean: /* Before Setting System Time */ Fixed excessive use of bash syntax highlighting.

2013-11-18T04:36:46Z

‎Before Setting System Time: Fixed excessive use of bash syntax highlighting.

Mdean: /* Before Setting System Time */ Fixed wording.

2013-11-18T04:34:54Z

‎Before Setting System Time: Fixed wording.

Mgloff: Reverted edits by Mgloff (talk) to last revision by Mdean

2013-11-13T19:01:23Z

Reverted edits by Mgloff (talk) to last revision by Mdean

Mgloff at 19:00, 13 November 2013

2013-11-13T19:00:35Z

← Older revision		Revision as of 20:38, 19 March 2014
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−	{{todo\|SEOKWREV (11.17.13-23:00->MD+);(03.04.14-15:35->BS-);(03.19.14-15:35->BS+)\|Klint Youngmeyer\|project=oe 4,oe 5,ky,md,bs SEOKWREV}}	+	{{todo\|SEOKWREV (11.17.13-23:00->MD+);(03.04.14-15:35->BS-);(03.19.14-15:35->BS+)\|Klint Youngmeyer\|project=oe 4,oe 5,ky,md,bs,SEOKWREV}}

	{{#seo:		{{#seo:

← Older revision		Revision as of 20:36, 19 March 2014
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−	{{todo\|~~SEOKWTODO~~ (11.17.13-23:00->MD+)(03.04.14-15:35->BS-)\|~~Brian Serrano~~\|project=oe 4,oe 5,ky,md,bs ~~SEOKWTODO~~}}	+	{{todo\|SEOKWREV (11.17.13-23:00->MD+);(03.04.14-15:35->BS-);(03.19.14-15:35->BS+)\|Klint Youngmeyer\|project=oe 4,oe 5,ky,md,bs SEOKWREV}}

		+	{{#seo:
		+	\|title=Setting the System Time
		+	\|titlemode=append
		+	\|keywords=Setting System Time,Updating Clock,Hardware Clock,Local Timezone
		+	\|description=Setting the system time on a Linux system.
		+	}}
	There are two different clocks on a Linux system. The RTC, or hardware clock, is present on most systems and is used to provide a persistent clock using a battery backup. It is also used for other purposes, like waking up the processor from suspend mode via an alarm interrupt. The hardware clock is generally only accessed to retrieve an initial time when Linux boots and is rarely accessed from a running system. The system clock is implemented in the kernel and is used for timekeeping purposes for the running system. On Linux, time is represented by the number of seconds after the Unix epoch: 00:00:00 UTC on January 1, 1970.		There are two different clocks on a Linux system. The RTC, or hardware clock, is present on most systems and is used to provide a persistent clock using a battery backup. It is also used for other purposes, like waking up the processor from suspend mode via an alarm interrupt. The hardware clock is generally only accessed to retrieve an initial time when Linux boots and is rarely accessed from a running system. The system clock is implemented in the kernel and is used for timekeeping purposes for the running system. On Linux, time is represented by the number of seconds after the Unix epoch: 00:00:00 UTC on January 1, 1970.

← Older revision		Revision as of 21:35, 4 March 2014
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−	{{todo\|~~Complete~~ (11.17.13-23:00->MD+)\|~~Klint Youngmeyer~~\|project=oe 4,oe 5,ky,md,~~Complete~~}}	+	{{todo\|SEOKWTODO (11.17.13-23:00->MD+)(03.04.14-15:35->BS-)\|Brian Serrano\|project=oe 4,oe 5,ky,md,bs SEOKWTODO}}

	There are two different clocks on a Linux system. The RTC, or hardware clock, is present on most systems and is used to provide a persistent clock using a battery backup. It is also used for other purposes, like waking up the processor from suspend mode via an alarm interrupt. The hardware clock is generally only accessed to retrieve an initial time when Linux boots and is rarely accessed from a running system. The system clock is implemented in the kernel and is used for timekeeping purposes for the running system. On Linux, time is represented by the number of seconds after the Unix epoch: 00:00:00 UTC on January 1, 1970.		There are two different clocks on a Linux system. The RTC, or hardware clock, is present on most systems and is used to provide a persistent clock using a battery backup. It is also used for other purposes, like waking up the processor from suspend mode via an alarm interrupt. The hardware clock is generally only accessed to retrieve an initial time when Linux boots and is rarely accessed from a running system. The system clock is implemented in the kernel and is used for timekeeping purposes for the running system. On Linux, time is represented by the number of seconds after the Unix epoch: 00:00:00 UTC on January 1, 1970.

@@ Line 65: / Line 65: @@
 </syntaxhighlight>
-{{Fmbox | type =  | text = Any portion of a format string with square brackets, such as [:ss], is optional for that format string.  To work correctly, the format string may need to be quoted as shown above or special characters may need to be escaped to prevent interpretation by the shell.}}
+{{imbox | type =  | text = Any portion of a format string with square brackets, such as [:ss], is optional for that format string.  To work correctly, the format string may need to be quoted as shown above or special characters may need to be escaped to prevent interpretation by the shell.}}
@@ Line 82: / Line 82: @@
-{{Fmbox | type =  | text = On some boards you may receive a message such as ''hwclock: RTC_RD_TIME: Invalid or incomplete multibyte or wide character'' or a similar message when attempting to read the hardware clock. This generally means that the hardware clock has not yet been set, in which case running the <code>hwclock --systohc</code> command will correct the issue.}}<br />
+{{imbox | type =  | text = On some boards you may receive a message such as ''hwclock: RTC_RD_TIME: Invalid or incomplete multibyte or wide character'' or a similar message when attempting to read the hardware clock. This generally means that the hardware clock has not yet been set, in which case running the <code>hwclock --systohc</code> command will correct the issue.}}<br />
 The system can be configured to use either local time (see [[#local_timezone|Local Timezone]]) or UTC for the hardware clock. Although the hardware clock only holds an absolute time value and no timezone value, adjustments can be made to account for the timezone when reading and setting the clocks. By default, EMAC OE uses the local time value for the hardware clock. If UTC is used for the system clock, or NTP or another method is used to synchronize the clocks, this will not cause an issue. However, if the hardware clock is the primary method used to initialize the system clock, there will be no way to automatically adjust for Daylight Saving Time changes that occur while the system is off. In these cases, it is best to keep the hardware clock in UTC. This can be done easily by adding the line <code>UTC=yes</code> to <code>/etc/default/rcS</code>. Doing so will cause the <code>/etc/init.d/hwclock.sh</code> script to pass the <code>utc</code> option to the <code>hwclock</code> command when setting the hardware clock and when using it to set the system clock. The following example illustrates how the <code>utc</code> option allows the system to automatically account for the timezone when setting and reading the clocks:
@@ Line 100: / Line 100: @@
 </syntaxhighlight>
-{{Fmbox | type =  | text =If the system is set to use UTC for the hardware clock setting, the <code>utc</code> option must be passed to <code>hwclock</code> if it is used outside of the <code>/etc/init.d/hwclock.sh</code> script to synchronize the hardware and system clocks.}}
+{{imbox | type =  | text =If the system is set to use UTC for the hardware clock setting, the <code>utc</code> option must be passed to <code>hwclock</code> if it is used outside of the <code>/etc/init.d/hwclock.sh</code> script to synchronize the hardware and system clocks.}}
 == Local Timezone ==

← Older revision		Revision as of 02:51, 20 December 2013
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−	{{todo\|(11.17.13-23:00->MD+)\|Klint Youngmeyer\|project=oe 4,oe 5,ky,md,Complete}}	+	{{todo\|Complete (11.17.13-23:00->MD+)\|Klint Youngmeyer\|project=oe 4,oe 5,ky,md,Complete}}

	There are two different clocks on a Linux system. The RTC, or hardware clock, is present on most systems and is used to provide a persistent clock using a battery backup. It is also used for other purposes, like waking up the processor from suspend mode via an alarm interrupt. The hardware clock is generally only accessed to retrieve an initial time when Linux boots and is rarely accessed from a running system. The system clock is implemented in the kernel and is used for timekeeping purposes for the running system. On Linux, time is represented by the number of seconds after the Unix epoch: 00:00:00 UTC on January 1, 1970.		There are two different clocks on a Linux system. The RTC, or hardware clock, is present on most systems and is used to provide a persistent clock using a battery backup. It is also used for other purposes, like waking up the processor from suspend mode via an alarm interrupt. The hardware clock is generally only accessed to retrieve an initial time when Linux boots and is rarely accessed from a running system. The system clock is implemented in the kernel and is used for timekeeping purposes for the running system. On Linux, time is represented by the number of seconds after the Unix epoch: 00:00:00 UTC on January 1, 1970.

@@ Line 11: / Line 11: @@
 Before setting the system time, you must use the following command to ensure that <code>ntpd</code> is not running.
-<syntaxhighlight lang="bash">
+<syntaxhighlight lang="console">
 root@emac-oe:~# ps | grep [n]tpd
 ntp     25066     1  0  9958  2260   2 Oct08 ?        00:00:07 /usr/sbin/ntpd -p /var/run/ntpd.pid -g -u 117:126
 root@emac-oe:~#
 </syntaxhighlight>
@@ Line 34: / Line 31: @@
 When ntpd is running, you can view a list of servers <code>ntpd</code> is using by running the command:
-<syntaxhighlight lang="bash">
+<syntaxhighlight lang="console">
 root@emac-oe:~# ntpq -q
 </syntaxhighlight>

@@ Line 55: / Line 55: @@
   <syntaxhighlight lang="bash">
 "hh:mm[:ss]"
-"[YY]YYMMDD hh:mm[:ss]"
+"[YYYY.]MM.DD-hh:mm[:ss]"
 </syntaxhighlight>
 hh     = hour<br />
 mm     = minute<br />
 ss     = second<br />
 MM     = month<br />
 DD     = day<br />
 [YY]YY = four-digit year where the first two digits are optional<br />
 {{Fmbox | type =  | text = Any portion of format string such as [:ss] with square brackets is optional for that format string. The format string must be quoted as shown above to work correctly.}}