Is there anything in unix crontab to determine this should be executed in PST/CST standard time?

Question

There is this thing in QuartzScheduler where we can say execute this in CST/BST/ or whatever timezone. This is also good when you want to execute some jobs in certain timezones and certain jobs in some other timezones.

Is there something like that in crontab where we can specify the timezone, because I have been seeing people going crazy numerous times when there is a timezone change and they have to go through the list of jobs in crontab where they have to change timings.

I am looking for something where we can execute certain jobs in certain timezones and certain other jobs in some other timezones.

Answer 1

This depends on your distribution: some versions of Cron support this, others don't. For example, on Debian:

LIMITATIONS
The cron daemon runs with a defined timezone. It currently does not support per-user timezones. All the tasks: system's and user's will be run based on the configured timezone. Even if a user specifies the TZ environment variable in his crontab this will affect only the commands executed in the crontab, not the execution of the crontab tasks themselves.

Whereas on Fedora:

The CRON_TZ specifies the time zone specific for the cron table. User type into the chosen table times in the time of the specified time zone. The time into log is taken from local time zone, where is the daemon running.

So check the crontab man page (man 5 crontab) on your system. (Both passages above are from that man page on the respective systems.)

Answer 2

It appears that there's no universal way to tell cron to schedule jobs in a specified per-user (or per-job) time zone.

But it shouldn't be hard to work around it. For example, if you want to run a job every day at 10:30am PST, you could write a wrapper and invoke it at 30 minutes after each hour:

30 * * * *    wrapper ...

The wrapper could then set its own time zone internally and then execute the specified command only if the current time is (close to) 10:30am. It would have to allow for a little bit of skew, since it's not going to execute at exactly 30 minutes after the hour.

If it's sufficiently useful, I might write such a wrapper myself. I'm thinking of a syntax like:

cron-wrapper -tz [zone] -time [time] command args...

Or, more simply, it might just specify the time as UTC and omit the timezone specification (which avoids having to decide on a syntax for specifying time zones).

To be clear, is your requirement, for example, to run a job at a specified CST (US Central Standard Time) time even if you're currently on CDT (Central Daylight Time), so that the job is always executed every 24 hours? So you want it to run at, say, 10:30am half the year and 11:30am the other half of the year? (Most people would want a job to run at a consistent wall clock time every day -- which is not to suggest that you should, but that's the usage that cron supports.)