NAME

       fake-hwclock - Control fake hardware clock

SYNOPSIS

       fake-hwclock [ command ] [ force ]

BACKGROUND

       Many  embedded  Linux  systems  do  not have a functional hardware clock. Either they simply don't have a
       hardware clock at all or they have a hardware clock but it is not usable (e.g. because Linux doesn't know
       how to use it or because no battery is present).

       This  can  lead  to time moving backwards to some default value (often 1970) when the system is rebooted.
       Since lots of software assumes that time only moves forward this is a bad  thing.  NTP  can  (and  should
       where  practical)  be  used to sync with an external timeserver but it is not available early in the boot
       process and may be unavailable for other reasons.

       The design expectation of fake-hwclock is that it will be run very late at shutdown  and  very  early  at
       boot.  This  will  ensure that fsck has a vaguely sensible idea of system time at boot and won't complain
       that the last-modified time in the filesystem is not hugely in the past or future.  Some  users  may  not
       worry  about  this  too use case, in which case it is possible to modify the init system configuration to
       move things earlier/later as appropriate.

DESCRIPTION

       fake-hwclock sets and queries a fake "hardware clock" which stores the time in a file. This  program  may
       be run by the system administrator directly but is typically run by init (to load the time on startup and
       save it on shutdown) and cron (to save the time hourly).

       If no command is given then fake-hwclock acts as if the save command was used.

COMMANDS

       save   Save the time to the file. As a sanity check, fake-hwclock will not move the saved clock backwards
              to a time/date earlier than its own release date. Use "force" to over-ride this check.

       load   Load  the  time  from  the  file.  If  force  is specified fake-hwclock will move the clock either
              backwards or forwards. Otherwise it will only move it forwards.

FILES

       /etc/fake-hwclock.data
              The file used to store the time

       /etc/init.d/fake-hwclock
              The init script used to run fake-hwclock on startup and shutdown

       /lib/systemd/system/fake-hwclock.service
              systemd service used to run fake-hwclock on startup and shutdown

       /etc/default/fake-hwclock
              Settings file for the init script.

       /etc/cron.hourly/fake-hwclock
              Cron job used to save the time hourly

ENVIRONMENT VARIABLES

       FILE   set the file used by fake-hwclock

RETURN VALUES

       1 is returned for invalid commands. 0 is returned in all other cases.

BUGS

       This approach can only provide a crude approximation of what a real hardware clock provides. Use  of  NTP
       or another method to keep the time in sync is strongly advised.