answer:At the UNIX prompt, type man crontab and help documentation will appear. — Crontab is the interface you use to schedule jobs in cron. It launches a basic text editor – usually vi but anything you want – and you enter in one line per scheduled job in the cron file. A line there might look something like: 56 4 23 1 * /path/to/shell_script_to_run_ROR.sh Which means: at 04:56 on January 23, regardless if it’s M-F, execute the program at /path/to/shell_script_to_run_ROR.sh. If you wanted something to run every Monday at 12 midnight: 00 00 * * 1 /path/to/run_something.sh Where the 1=Monday. For the other days of the week 0=Sunday and 6=Saturday. Again, see the man page for more details, options, and examples. One more thing, a cron file cannot have any blank lines in it. Also, if anything is wrongly formatted, then none of the scheduled jobs may be able to run. You can start a line with the pound sign, #, for comments, like so: # This is my crontab #————————————————————- # # Run some maintenance every Wednesday night at 9:30pm. 30 21 * * 3 /path/to/maintenance.sh # #————————————————————-