how to generate cron expression through millisecond..?

Question

I need to generate the cron expression based on milliseconds. For example: what will be the cron expression for 86400(milliseconds) and how to get the expression..? Please help..

Thanks...

Answer 1

cron is not intended for high-accuracy timing ! Forget about seconds or even milliseconds precision here. The best you can get is minutes.

cron CAN be and is frequently off by several seconds (due to process start-up, ...).

If you really require that kind of precision, you should build your own daemon (unless I got your question wrong).

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If your intend is "just" to convert second/millisecond time to crontab expression. Then:

• I assume these jobs are daily jobs, that is <second_number> < 84600
• 1st arg = minutes of the hour = int( (<second_number> % 3600) / 60)
• 2nd arg = hours of the day = int( (<second_number> / 3600) )
• 3rd arg = every day of the month = *
• 4th arg = every month of the year = *
• 5th arg = every day of the week = *

For more have look at the crontab man page.