Nastavení datumu a času

To display the current date and time along with detailed information about the configuration of the system and hardware clock, run the timedatectl command with no additional command line options:

This displays the local and universal time, the currently used time zone, the status of the Network Time Protocol (NTP) configuration, and additional information related to DST.

To change the current time, type the following at a shell prompt as root:

Replace HH with an hour, MM with a minute, and SS with a second, all typed in two-digit form.

This command updates both the system time and the hardware clock. The result it is similar to using both the date --set and hwclock --systohc commands.

The command will fail if an NTP service is enabled. See Synchronizing the System Clock with a Remote Server to temporally disable the service.

By default, the system is configured to use UTC. To configure your system to maintain the clock in the local time, run the timedatectl command with the set-local-rtc option as root:

To configure your system to maintain the clock in the local time, replace boolean with yes (or, alternatively, y, true, t, or 1). To configure the system to use UTC, replace boolean with no (or, alternatively, n, false, f, or 0). The default option is no.

To change the current date, type the following at a shell prompt as root:

Replace YYYY with a four-digit year, MM with a two-digit month, and DD with a two-digit day of the month.

Note that changing the date without specifying the current time results in setting the time to 00:00:00.

To list all available time zones, type the following at a shell prompt:

To change the currently used time zone, type as root:

Replace time_zone with any of the values listed by the timedatectl list-timezones command.

As opposed to the manual adjustments described in the previous sections, the timedatectl command also allows you to enable automatic synchronization of your system clock with a group of remote servers using the NTP protocol. Enabling NTP enables the chronyd or ntpd service, depending on which of them is installed.

The NTP service can be enabled and disabled using a command as follows:

To enable your system to synchronize the system clock with a remote NTP server, replace boolean with yes (the default option). To disable this feature, replace boolean with no.

To display the current date and time, run the date command with no additional command line options:

This displays the day of the week followed by the current date, local time, abbreviated time zone, and year.

By default, the date command displays the local time. To display the time in UTC, run the command with the --utc or -u command line option:

You can also customize the format of the displayed information by providing the +"format" option on the command line:

Replace format with one or more supported control sequences as illustrated in Displaying the Current Date and Time. See Commonly Used Control Sequences for a list of the most frequently used formatting options, or the date(1) manual page for a complete list of these options.

To change the current time, run the date command with the --set or -s option as root:

Replace HH with an hour, MM with a minute, and SS with a second, all typed in two-digit form.

By default, the date command sets the system clock to the local time. To set the system clock in UTC, run the command with the --utc or -u command line option:

To change the current date, run the date command with the --set or -s option as root:

Replace YYYY with a four-digit year, MM with a two-digit month, and DD with a two-digit day of the month.

Note that changing the date without specifying the current time results in setting the time to 00:00:00.

Running hwclock with no command line options as the root user returns the date and time in local time to standard output.

Note that using the --utc or --localtime options with the hwclock command does not mean you are displaying the hardware clock time in UTC or local time. These options are used for setting the hardware clock to keep time in either of them. The time is always displayed in local time. Additionally, using the hwclock --utc or hwclock --local commands does not change the record in the /etc/adjtime file. This command can be useful when you know that the setting saved in /etc/adjtime is incorrect but you do not want to change the setting. On the other hand, you may receive misleading information if you use the command an incorrect way. See the hwclock(8) manual page for more details.

For information on how to change the time zone, see Changing the Time Zone.

Besides displaying the date and time, you can manually set the hardware clock to a specific time.

When you need to change the hardware clock date and time, you can do so by appending the --set and --date options along with your specification:

Replace dd with a day (a two-digit number), mmm with a month (a three-letter abbreviation), yyyy with a year (a four-digit number), HH with an hour (a two-digit number), MM with a minute (a two-digit number).

At the same time, you can also set the hardware clock to keep the time in either UTC or local time by adding the --utc or --localtime options, respectively. In this case, UTC or LOCAL is recorded in the /etc/adjtime file.

You can synchronize the hardware clock and the current system time in both directions.

When you synchronize the hardware clock and the system time, you can also specify whether you want to keep the hardware clock in local time or UTC by adding the --utc or --localtime option. Similarly to using --set, UTC or LOCAL is recorded in the /etc/adjtime file.

The hwclock --systohc --utc command is functionally similar to timedatectl set-local-rtc false and the hwclock --systohc --local command is an alternative to timedatectl set-local-rtc true.