MPE/iX Commands Reference Manual (32650-90877)

Chapter 12 473
Command List X
Commands SAVE thru SHUTQ
• Some compilation tools like MAKE rely on the relative modification dates of the files in
the compilation unit. Setting the system time backward and then modifying the main
file in the compilation unit may force an unnecessary full compilation, since the main
file may have an earlier modification time than the files it depends on. Setting the
system time backward and then changing a file needed by the main file will cause
MAKE to think that the changed file's modification time precedes that of the main file.
Thus, the changed file will not be included in the recompilation.
This list is only meant to include a few of the dangers associated with an immediate time
change; this list does not represent all of the problems likely to be encountered.
Therefore, if the ;NOW option must be used, it should be used only with a full
knowledge of its effects on the system's workload.
Use
This command may be issued from a session, job, program, or in BREAK. Pressing
Break
has no effect on this command.
Diagnostician (DI) and either Operator (OP) or System Manager (SM) capabilities are
required to issue this command. Additionally, System Manager (SM) capabiltiy is required
to use the ;NOW parameter.
Examples of Date-Time and Correction Forms:
The following example illustrates setting the system time by providing a date and time:
:SETCLOCK DATE=07/04/1993;TIME=15:00
The following example illustrates providing a time correction to advance the system time
by one hour.
:SETCLOCK CORRECTION= +3600
or
:SETCLOCK CORRECTION= 3600
Both of the above examples cause Universal Time (GMT) to change as well as local time,
and therefore while they are useful in correcting the system time for drift (time gain or
loss), they are not accurate ways to change time zones.
The following example illustrates setting a time correction, executing a SHOWCLOCK
command, cancelling the correction, then again executing a SHOWCLOCK command. Note
that by the time of the first SHOWCLOCK the correction has already begun to be consumed.
:SETCLOCK CORRECTION= -3600
:SHOWCLOCK
SYSTEM TIME: FRI, JUL 24, 1987, 8:47:35 AM
CURRENT TIME CORRECTION: -3568 SECONDS
TIME ZONE: 7 HOURS 0 MINUTES WESTERN HEMISPHERE
:SETCLOCK; CANCEL
CORRECTION OF -3550 SECONDS HAS BEEN CANCELLED