s6-portable-utils
Software
skarnet.org
s6-clock gets or sets the system clock.
s6-clock [ label ]
When called without an argument, s6-clock writes the current system time, as a TAI64N timestamp, to stdout.
When given an argument label, which must be a TAI64N timestamp, s6-clock sets the system time to this value.
s6-clock only prints or accepts TAI time, no matter what the system clock is set to (TAI-10 or UTC); it will automatically make the right conversions for your system clock. Make sure your skalibs has been built with the right settings.