Hi. Thanks for the info! -- A message from the system administrator: "I've upped my priority, now up yours!" On Sat, 14 Jun 2003, Adam Myrow wrote: > The syntax of the crontab file is downright odd, but it's been this way in > just about every Unix system or Linux system I've encountered. > > The first entry is the minute or minutes on which you want your cron job > to run. For every 15 minutes, you would use "0,15,30,45, in the first > field. The second field is the hour. It is expressed in 24-hour notation > from 0 to 23. The third field is the day of the month you want to run the > cron job. The fourth field is the month or months of the year to run the > cron job. The fifth field is the day of the week from 0 for Sunday to 6 > for Saturday. All of these fields can take a single value, a > comma-separated list of values, a range, or an asterisk which means any. > For example, if you wanted the time announced every 15 minutes, and you > had a command called "saytime," you would put something like this in your > crontab file. > > 0,15,30,45 * * * * /usr/local/bin/saytime >/dev/null 2>&1 > > It is generally a good idea to include the full path to commands since the > path can be set up oddly when running a cron script. You also generally > want to redirect both standard out and standard error somewhere. > Otherwise, any output gets mailed to the user who has the cron job. This > is a good thing in some cases, but not so good in a lot of others. > Instead of /dev/null, you could use the ">> /var/log/saytime.log" to > append output to that file. In the case of "saytime" it seldom produces > output other than an error saying that the device is busy, so we don't > really need to log it. Check out the default crontab file. It has some > cron entries already set up. As I said, this applies to just about any > Unix system you can think of. Some crontab programs will have special > features like being able to understand symbolic names like MON instead of > the numbers, but I stick with the most portable format. > > Here is another example. suppose you leave your computer on 24 hours a > day. That Saytime program is keeping you up all night! How to shut it up > while letting it run in the daytime? Try this. > > 0,15,30,45 8-20 * * * /usr/local/bin/saytime >/dev/null 2>&1 > > Now, the cron entry will only run from 8 A.M. to 8 P.M. I think you get > the idea. These are just examples I made up off the top of my head. > > Lastly, always use "crontab -e" to edit cron files. If you don't like the > editor it starts with, set the environment variable "EDITOR" to point to > your favorite editor. For example "export EDITOR='pico -t'" or "export > EDITOR=emacs." Since some programs use VISUAL instead of EDITOR, I have > my .profile export both variables and give them the same value. This > effects most news readers, and most other email readers besides Pine which > has its own option for setting an editor. I hope this was helpful. > > > _______________________________________________ > Speakup mailing list > Speakup at braille.uwo.ca > http://speech.braille.uwo.ca/mailman/listinfo/speakup >
