January 30, 1997
Instructor: Marty Pagel
It is always a good idea to choose a graphics format that is multi-Operating System supported if you want to transfer these files across platforms. to convert a file from one format to another, first make sure that the program you use supports both file formats. Then, open the file under that program. After that, save a copy of the file under a different file format (usually there is a command such as "Save as..."). Here are some suggestions on selecting the best graphics formats:
at and batch read commands from standard input to be executed at a later
time. at allows you to specify when the commands should be executed,
while jobs queued with batch will execute when system load level permits.
at may be used with the following options:
-r Removes jobs previously scheduled with at.
-l Reports all jobs scheduled for the invoking user.
-q Put job onto specified queue.
batch submits a batch job. It is almost equivalent to ``at now'', but not quite. For one, it goes into a different queue. For another, ``at now'' will respond with the error message too late.
at removes jobs previously scheduled by at or batch. The job number is the number given to you previously by the at or batch command. You can also get job numbers by typing at -l. You can only remove your own jobs unless you are the super-user.
This sequence, which demonstrates redirecting standard error to a pipe,
is useful in a shell procedure (the sequence of output redirection
specifications is significant):
batch <<!
sort filename 2>&1 >outfile | mail loginid
!
To have a job reschedule itself, invoke at from within the shell
procedure, by including code similar to the following within the shell
file:
echo "sh shellfile" | at 1900 thursday next week
or, from a terminal
at 1900 thursday next week
sh shellfile
<control-D> (hold down 'control' and depress 'D')