Run a cron job every minute only on specific hours?

Question

How do you run a cron job every minute only on specific hours? Like so:

It will only check every minute from 11AM to 12AM, 4PM to 5PM and 9PM to 10PM<

Answer 1

As per the cron format

<Minute> <Hour> <Day_of_the_Month> <Month_of_the_Year> <Day_of_the_Week> <Year>

* * * * * *
| | | | | | 
| | | | | +-- 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)

the solution should be

* 11,16,21 * * * *

Answer 2

Right solution:

* 11,16,21 * * *

Because if you use previous solution:

0-59 11-12,16-17,21-22 * * * *

Job will start at 12:40 or 17:59. It is not in range from 11AM to 12AM, 4PM to 5PM and 9PM to 10PM.

UPDATE:

Traditional (inherited from Unix) cron format consists of five fields separated by white spaces:

*    *    *    *    *  command to be executed
┬    ┬    ┬    ┬    ┬
│    │    │    │    │
│    │    │    │    │
│    │    │    │    └───── day of week (0 - 6) (0 is Sunday, or use names)
│    │    │    └────────── month (1 - 12)
│    │    └─────────────── day of month (1 - 31)
│    └──────────────────── hour (0 - 23)
└───────────────────────── min (0 - 59)

nnCron can use both traditional and "enhanced" version of cron format, which has an additional (6th) field: Year.