chronyd

chronyd is chrony's daemon, the program that keeps a clock right with NTP. Given config lines on the command line it reads no config file, so chronyd -Q 'server SERVER iburst' asks that one server a few quick questions, prints System clock wrong by X seconds (ignored) and exits: the offset, measured and not applied. It is the modern ntpdate -q, and it runs beside a chronyd that is already keeping the clock.

chronyd command usage

chronyd -Q 'server SERVER iburst'
chronyd -q 'server SERVER iburst'
chronyd [-d] [-x] [-f CONFIG]

Options

-Q

ask once, print the offset, set nothing, exit

-q

ask once, set the clock, exit

'server SERVER iburst'

a config line on the command line: the server to ask, with a quick first burst

-x

never touch the system clock

-d

stay in the foreground and log to the terminal

chronyd examples

chronyd -Q 'server timeServer.lab iburst'

Asks timeServer how far off this clock is, and changes nothing.

System clock wrong by 0.000026 seconds (ignored)

chronyd -Q 'pool pool.ntp.org iburst'

Asks several servers of a public pool at once and prints the combined offset.

chronyd -q 'server timeServer.lab iburst'

Steps the clock to timeServer's time once, then exits.

Pitfalls

• A negative offset means this clock is ahead of the server's.
• -q sets the clock; inside a container that shares the host's clock it fails, or worse, moves the host's.

Run it on real machines