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21.1.2 Setting the time

You must have appropriate privileges to set the system clock. For changes to persist across a reboot, the hardware clock may need to be updated from the system clock, which might not happen automatically on your system.

To set the clock, you can use the --set (-s) option (see Options for date). To set the clock without using GNU extensions, you can give date an argument of the form ‘MMDDhhmm[[CC]YY][.ss]’ where each two-letter component stands for two digits with the following meanings:

MM

month

DD

day within month

hh

hour

mm

minute

CC

first two digits of year (optional)

YY

last two digits of year (optional)

ss

second (optional)

The --date and --set options may not be used with an argument in the above format. The --universal option may be used with such an argument to indicate that the specified date and time are relative to Universal Time rather than to the local time zone.