clock daylight-saving-time

Function

The clock daylight-saving-time command sets the name, start time, and end time of the daylight saving time (DST).

The undo clock daylight-saving-time command cancels the DST settings.

By default, DST is not used.

Format

clock daylight-saving-time time-zone-name one-year start-time start-date end-time end-date offset

clock daylight-saving-time time-zone-name repeating start-time { { first | second | third | fourth | last } weekday month | start-date1 } end-time { { first | second | third | fourth | last } weekday month | end-date1 } offset [ start-year [ end-year ] ]

undo clock daylight-saving-time

Parameters

Parameter	Description	Value
time-zone-name	Specifies the name of the DST zone.	The value is a string of 1 to 32 case-sensitive characters without spaces.
one-year	Specifies absolute DST.	-
repeating	Specifies periodic DST.	-
start-time	Specifies the DST start time.	The start time is in 24-hour format HH:MM. HH specifies the hour, which is an integer ranging from 0 to 23. MM specifies the minute, which is an integer ranging from 0 to 59. If MM is not specified, DST starts on the hour. You must enter at least one digit to specify HH. For example, when you enter 0, the start time is 00:00.
start-date	Specifies the DST start date.	The start date is in the format YYYY-MM-DD. YYYY specifies the year, which is an integer ranging from 2000 to 2099, MM specifies the month, which is an integer ranging from 1 to 12, and DD specifies the day, which is an integer ranging from 1 to 31.
end-time	Specifies the DST end time.	The end time is in 24-hour format HH:MM. HH specifies the hour, which is an integer ranging from 0 to 23. MM specifies the minute, which is an integer ranging from 0 to 59. If MM is not specified, DST starts on the hour. You must enter at least one digit to specify HH. For example, when you enter 0, the start time is 00:00.
end-date	Specifies the DST end date.	The end date is in the format YYYY-MM-DD. YYYY specifies the year, which is an integer ranging from 2000 to 2099, MM specifies the month, which is an integer ranging from 1 to 12, and DD specifies the day, which is an integer ranging from 1 to 31.
first	Specifies the first workday in a month.	-
second	Specifies the second workday in a month.	-
third	Specifies the third workday in a month.	-
fourth	indicates the fourth workday in a month.	-
last	Specifies the last workday in a month.	-
weekday	Specifies a day of the week.	The value is Mon, Tue, Wed, Thu, Fri, Sat, or Sun.
month	Specifies a month.	The value is Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, or Dec.
start-date1	Specifies the DST start date.	The start date is in the format MM-DD. MM specifies the month, which is an integer ranging from 1 to 12, and DD specifies the day, which is an integer ranging from 1 to 31.
end-date1	Specifies the DST end date.	The end date is in the format MM-DD. MM specifies the month, which is an integer ranging from 1 to 12, and DD specifies the day, which is an integer ranging from 1 to 31.
offset	Specifies the DST offset.	The offset is in 24-hour format HH:MM. HH specifies the hour, which is an integer ranging from 0 to 23. MM specifies the minute, which is an integer ranging from 0 to 59. If MM is not specified, the offset is the specified hours. You must enter at least one digit to specify HH.
start-year	Specifies the start year.	The start year is in the format YYYY and ranges from 2000 to 2099.
end-year	Specifies the end year.	The end year is in the format YYYY and ranges from 2000 to 2099.

Views

User view, system view

Default Level

3: Management level

Usage Guidelines

Usage Scenario

DST, also referred to as summer time, is a convention intended to save resources. In high latitude areas, sunrise time is earlier during summer than it is during winter. To reduce use of incandescent lighting in the evenings and save energy, clocks are adjusted forward one hour.

Users can customize the DST zone according to their countries' or regions' convention. In addition, users can set how far ahead clocks are adjusted forward, usually an hour. With DST enabled, when it is time to start DST, the system time is adjusted according to the user-specified DST. When it is time to end DST, the system time automatically returns to the original time.

Configuration Impact

To configure DST, note the following:

The time in logs and debugging information uses the local time adjusted based on the time zone and the configured DST.
The time in the output of the display commands uses the local time adjusted based on the time zone and the configured DST.

To remove configurations for DST, note the following:

If DST has already taken effect when you remove the configurations, the device will adjust its clock by subtracting the value of the offset parameter from the current time.
If DST has not taken effect, removing the configurations will not affect the system time.

Precautions

The DST is configured in the summer. The DST duration ranges from one day to one year.
You can configure the start time and end time for periodic DST in one of the following modes: date+date, week+week, date+week, and week+date.
When you run the clock daylight-saving-time command in either the user or system view, the configuration files are both generated in the system view. You are advised to run this command in the system view.

Example

# Set periodic DST.

<HUAWEI> system-view
[HUAWEI] clock daylight-saving-time bj repeating 0 first sun jan 0 first sun apr 2 2009 2009

# Set periodic DST by day.

<HUAWEI> system-view
[HUAWEI] clock daylight-saving-time bj repeating 12:11 1-1 1:0 3-4 1

# Set absolute DST.

<HUAWEI> system-view
[HUAWEI] clock daylight-saving-time bj one-year 12:11 2010-10-2 1:00 2010-11-4 1