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.Dd December 15, 1993 .Dt ADJKERNTZ 8 .Os FreeBSD .Sh NAME .Nm adjkerntz .Nd "adjusts the kernel time if the machine runs wall CMOS clock" .Sh SYNOPSIS .Nm adjkerntz .Sh DESCRIPTION .Nm Adjkerntz daemon fixes kernel time (makes it UTC) using the current wall CMOS clock value, the current time zone rule and the kernel timezone value. The adjustment is enabled only if the file
a /etc/wall_cmos_clock exists, in other cases it is assumed that the machine runs UTC CMOS clock and .Nm adjkerntz does nothing and exits immediately.
p The adjustment is usually needed at boot stage and when a time zone change occurs. .Nm Adjkerntz started in
a /etc/rc (before any daemons are started). .Nm Adjkerntz makes the first adjustment and the initial time zone offset is stored into
a adjkerntz kernel variable for following subsequent .Nm adjkerntz time zone change spying. When time zone changes occur, .Nm Adjkerntz uses the previously stored time zone offset and the changed time zone rule to produce the new time zone offset, fix RTC clock and store the new offset into
a adjkerntz kernel variable too.
p .Nm Adjkerntz clears the kernel timezone structure and makes kernel always run at UTC time zone. Super-user privilege is required for all operations. .Sh ENVIRONMENT l -tag -width Fl t Ev TZ Time zone change rule, see .Xr tzset 3 ; not needed when .Xr /usr/sbin/tzsetup or .Xr zic 8 is used. .Sh FILES l -tag -width /etc/wall_cmos_clock -compact t Pa /etc/localtime current zoneinfo file, see .Xr /usr/sbin/tzsetup and .Xr zic 8 . t Pa /etc/wall_cmos_clock Empty file. Presence of it indicates that the machine runs wall CMOS clock, absence indicates UTC CMOS clock. .Sh SEE ALSO .Xr tzset 3 , .Xr zic 8 , .Xr rc 8 , .Xr sysctl 8 , .Xr /usr/sbin/tzsetup .Sh DIAGNOSTICS No diagnostics. If any error occurs, an error message printed via .Xr syslog 3 and .Nm adjkerntz exits with return code greater than zero. .Sh AUTHOR Andrew A. Chernov <ache@astral.msk.su> .Sh HISTORY The .Nm adjkerntz command appeared in FreeBSD 1.0.1