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How to create a cronjob that will execute some code from 8:30AM to 8:14PM.

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Do you want to run a script repeatedly between 8:30AM and 8:14PM, or do you want a script to run once at 8:30AM, keep running, and then STOP running at 8:14PM? – Jim Salter Nov 22 '12 at 17:53

This link has some good info. Crontabs support ranges in a very straight forward way.

14-30 8 * * * /code/to/execute

This will run once a minuet from 8:14 to 8:30

Check the Man page with man crontab next time it has some very good examples, including this one.

Cron is only used to start programs though, so make sure you don't overlap running instances of your program.

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What if I want to execute the a code continuously from 8:30AM to 12:14PM. – droidlabour Nov 22 '12 at 7:26
This is not what cron is for, you can "hack" it by running a start cron at 30 8 * * * and a kill command 14 12 * * * – coteyr Nov 22 '12 at 7:28
I didn't understand. – droidlabour Nov 22 '12 at 7:32
30 8 * * * prog-to-run 14 12 * * * killall prog-to-run – coteyr Nov 22 '12 at 7:47

As a coder I would suggest the following method:

1 line inside your cron to start the script

30 8 * * * /code/to/execute1

execute1 starts your script. You script has a while that ends when time passes 20:14 so it keeps running until 20:14 is reached (something like while current_time < 20:14).

Killing a script could have side effects: just maybe the script is currently doing something important. Killing it will without any mercy end it. Gracefully exiting a program is always better.

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Ubuntu documentation CronHowto


Webmin has a gui for cron jobs (System --> Scheduled Cron Jobs)

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