|
Running Jobs Once We've talked at length about crond
and its ability to run many scheduled jobs over a 24-hour period. Suppose,
though, that you have a job you'd like to run unattended, but only once. Surely
you don't have modify the crontab file for a single execution then remove the
entry. Indeed not. Linux distributions contain the right tool for just such a
situation - the at require
very few parameters. First, you'll need to enter the time at which you'd like
the job to be executed. Then, you'll need to enter all the commands to be
executed by the job. Finally, Ctrl-D submits the job, returning a job number,
date and time. At this point, an example is useful. You're an avid Mozilla user. You
know that Mozilla releases "daily builds" on the mozilla.org site
each night, and you'd like to see what's up with your favorite browser.
However, you'd like to schedule the download at an off-peak time and have the
unzipped and untarred file waiting in the morning. Here's how you would use at to complete the task: at ncftpget, by the
way, is a program to download files via ftp without actually sitting at your
computer. In our example, Ctrl-D schedules the job as entered and escapes,
printing something like the following: job 1 at
2002-02-08 If you're like me, you're likely
to enter a few jobs, then forget what they were. You can always review
outstanding at jobs with the atq
command. This command returns a list of the scheduled jobs by job number. Now the real fun - put the at command to good use on your own system,
completing one-time jobs unattended and behind your back. |
