Crontab Format

* * * * * *
| | | | | | 
| | | | | +-- Year              (range: 1900-3000)
| | | | +---- Day of the Week   (range: 1-7, 1 standing for Monday)
| | | +------ Month of the Year (range: 1-12)
| | +-------- Day of the Month  (range: 1-31)
| +---------- Hour              (range: 0-23)
+------------ Minute            (range: 0-59)

Examples:

* * * * * *                         Each minute


59 23 31 12 5 *                     One minute  before the end of year if the last day of the year is Friday
									
59 23 31 DEC Fri *                  Same as above (different notation)


45 17 7 6 * *                       Every  year, on June 7th at 17:45


45 17 7 6 * 2001,2002               Once a   year, on June 7th at 17:45, if the year is 2001 or  2002


0,15,30,45 0,6,12,18 1,15,31 * 1-5 *  At 00:00, 00:15, 00:30, 00:45, 06:00, 06:15, 06:30,
                                    06:45, 12:00, 12:15, 12:30, 12:45, 18:00, 18:15,
                                    18:30, 18:45, on 1st, 15th or  31st of each  month, but not on weekends


*/15 */6 1,15,31 * 1-5 *            Same as above (different notation)


0 12 * * 1-5 * (0 12 * * Mon-Fri *) At midday on weekdays


* * * 1,3,5,7,9,11 * *              Each minute in January,  March,  May, July, September, and November


1,2,3,5,20-25,30-35,59 23 31 12 * * On the  last day of year, at 23:01, 23:02, 23:03, 23:05,
                                    23:20, 23:21, 23:22, 23:23, 23:24, 23:25, 23:30,
                                    23:31, 23:32, 23:33, 23:34, 23:35, 23:59


0 9 1-7 * 1 *                       First Monday of each month, at 9 a.m.


0 0 1 * * *                         At midnight, on the first day of each month


* 0-11 * * *                        Each minute before midday


* * * 1,2,3 * *                     Each minute in January, February or March


* * * Jan,Feb,Mar * *               Same as above (different notation)


0 0 * * * *                         Daily at midnight


0 0 * * 3 *                         Each Wednesday at midnight

In extended mode, crontab notation may be abridged by omitting the rightmost asterisks.

Examples: (only for extended mode)

Full notation                         Abridged notation

* * * * * * 

59 23 31 12 5 2003                    59 23 31 12 5 2003

59 23 31 12 5 *                       59 23 31 12 5

45 17 7 6 * *                         45 17 7 6

0,15,30,45 0,6,12,18 1,15,31 * * *    0,15,30,45 0,6,12,18 1,15,31

0 12 * * 1-5 *                        0 12 * * 1-5

* * * 1,3,5,7,9,11 * *                * * * 1,3,5,7,9,11

1,2,3,5,20-25,30-35,59 23 31 12 * *   1,2,3,5,20-25,30-35,59 23 31 12

0 9 1-7 * 1 *                         0 9 1-7 * 1

0 0 1 * * *                           0 0 1

* 0-11 * * * *                        * 0-11

* * * 1,2,3 * *                       * * * 1,2,3

0 0 * * * *                           0 0

0 0 * * 3 *                           0 0 * * 3

Both in classic and extended modes, nnCron users can use a «nonstandard» character «?» in the first four fields of cron format. It stands for time of nnCron startup, i. e. when a field is processed, startup time will be substituted for the question mark: minutes for Minute field, hour for Hour field, day of the month for Day of month field and month for Month field.

For example, if you write the following:

Time: ? ? * * * *

the task will be executed on nnCron startup and then will be executed daily at the same time (unless the user doesn’t restart nnCron, of course): question marks will be «replaced» by nnCron startup time. For example, if nnCron was started at 8:25, question marks will be substituted this way:

Time: 25 8 * * * *

Some more examples:

\ task will be executed only on nnCron startup 
\ (this has the sane effect  as "Time: START-TIME")
Time: ? ? ? ? * *

\ task will be executed on nnCron startup (e.g. at 10:15) 
\ and then will be executed again each hour: 
\ at 11:15, 12:15, 13:15 etc.
Time: ? * * * * *

\ task will be started each minute after nnCron startup until the next hour starts. 
\ The next day, if nnCron has not been restarted in the meanwhile,  
\it will be executed again each minute during the same hour.
Time: * ? * * * * 

\ task will be executed daily,  every five minutes,
\ during the hour when nnCron was started.
Time: */5 ? * * * *