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**** The Hebrew University of Jerusalem ****
**** Computation Center ****
News Bulletin #22
4-August-1991
Today's topics:
- Disk space.
- Mail files - how to clean them?
- Exiting mail and other programs correctly.
- Batch restarts.
o Disk space - Our disks are filling over the maximum recommended
capacity. All users are requested to delete files they do not need
and purge old versions of files. Please clean also old mail files
which you don't need, as they account for a noticeable portion of
the occiupied disk space.
o Mail files - how to clean them: A lot of users think that they
delete old messages while in practice this is not done. This is
caused by a feature of VMS/MAIL. When you delete messages in
VMS/MAIL they are not deleted immediately (not true for BMAIL).
They are moved to a folder named WASTEBASKET so you can still
retreive them from there. If you leave MAIL with ^C or QUIT command
they are left there (although you think they are gone). The
"correct" way to exit MAIL (unless you have a good reason not to) is
to use EXIT command or ^Z. These commands will clear WASTEBASKET
folder. You may also use the command PURGE inside MAIL to do the
real deletion of the deleted messages and clear the WASTEBASKET
folder.
o Exiting programs correctly - This is somewhat a generalization of
the previous paragraph. MAIL is just one in a set of programs that
follow the conventions of EXIT and QUIT commands: EXIT command
keeps all the changes you have done and updates whatever is needed
when you issue this command. QUIT ignores (where applicable) the
changes you did in the last session. The programs that adhere to
this convention are: MAIL, editors, ANUNEWS and others. BMAIL for
example is an exception - QUIT is treated as EXIT.
o Batch restarts - Thinking on the coming sunctions of the electricity
company workers we would like to remind you the batch restart
mechanism available on the VAX. Although it is quite primitive it
might give you usefull results.
When the system stops due to power failure nothing can be
remembered about the executing jobs. Batch jobs are an exceptions
as the batch controlling job saves in a file a list of executing
batch processes along with a setable value. When the system starts
after a power failure the batch manager can use this information to
rerun the batch job. In order for this to happen you must submit
your job with the qualifier /RESTART. This will cause your batch to
be resubmitted automatically after the power failure.
How do we know whether this is the first time or not? A simple
way is provided for it. The DCL symbol $RESTART is true if the job
was submitted for the second time (restarted) and false otherwise.
For example:
$ IF $RESTART THEN WRITE SYS$OUTPUT "RESTARTED" -
ELSE WRITE SYS$OUTPUT "FIRST TIME"
However, this is usually not enough. If your job consists of a few
steps, each one is a different DCL step and you can restart between
these steps you can save a value to tell you where your job was
checkpointed the last time. To do it:
$ SET RESTART_VALUE = something
and then, if your job was restarted ($RESTART is true) the value
given in the last SET RESTART_VALUE command is accessible in the DCL
symbol BATCH$RESTART.
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