Chapter 7 547
Command Definitions S-SO
SETCLOCK
SETCLOCK
Alters the system time or system time zone.
SYNTAX
SETCLOCK{DATE=date spec; TIME=time spec [ ;GRADUAL | ;NOW]}
{CORRECTION= correction spec}
{TIMEZONE= time zone spec}
{ ;CANCEL}
Parameters
date spec A specification of local date in the form mm/dd/yy[yy]. The year may be
expressed in two or four digits. If a date is provided, a time must also be
provided.
time spec A specification of local time in the form hh:mm[:ss] where seconds are
optional. This specification uses a 24-hour clock; it is not permissible to
specify the time using A.M. or P.M. If a time is provided, a date must also
be provided.
The operating system will experience problems if the system date and time
are too close to the base time of midnight, January 1, 1970. Therefore, for
proper system operation this command requires the date and time to be
later than ten minutes past midnight on January 1, 1970.
correction spec An integer specifying the desired change in the system time. The units are
seconds. Thus a positive correction will cause the system clock to advance
by the specified number of seconds, while a negative correction will cause
the system clock to slow by the specified number of seconds.
time zone spec A specification of the time zone in the form hh:mm, preceded by a required
"W" or "E" to specify the Western or Eastern Hemisphere. Thus a
specification of W7:00 represents a seven-hour displacement from
Universal Time (GMT) with the time zone being in the Western
Hemisphere.
Providing a time zone spec is the only way to change the system time and
maintain both local and Universal Time (GMT) accurately. See the
Operation Notes section for details.
GRADUAL This option is meaningful only when the date and time specifications are
provided. GRADUAL causes the system clock to speed up or slow down until
the time change is completed, at which time the system clock will resume
its normal pace. GRADUAL is the default for the Date-Time form of the
command.
