override the system date-timestamp on the Unix servers

DavidH · #1 (**permalink**) 09-26-2007

I am looking for a tool that allows us to override the system date-timestamp on the Unix servers so that we can perform regression tests using the same set of scripts and data. CDS is an example of a system where the logic is very date/time dependent. It would make regression testing much easier and more reliable if we could always start the tests at the same date/time. I recall back in the Y2K days there was a tool that allowed us to do that on the Unisys mainframe, but not sure about Unix.

porter · #2 (**permalink**) 09-26-2007

disable NTP

set time to what you want

DavidH · #3 (**permalink**) 09-26-2007

Yes, a great suggestion but that requires screwing with the servers and rebooting before each test. I don't want to do that. I want the server to maintain its time so files created are time stamped appropriately. I want the utility to fake out the system so that when the code calls for the current date/time it gets what I want it to be. I want to be able to run multiple iterations of tests using current and past dates. Do you have any other suggestions? Thanks again for the prompt response!

Perderabo · #4 (**permalink**) 09-26-2007

I doubt that you will find any option other that resetting the system's internal clock. But this does not require a reboot. Shut down cron, change the date, and restart cron.

porter · #5 (**permalink**) 09-26-2007

Quote:

Originally Posted by Perderabo

....But this does not require a reboot...

pthread_cond_timedwait() takes an absolute time, if you step back six months any threaded code waiting on one of these will wait six months.

Oh, and don't use NFS across time discontinuities.

jim mcnamara · #6 (**permalink**) 09-27-2007

The system time is kept in the kernel, and maintained by it. The only other solution other than what Porter and Perderabo mentioned is to have a small dedicated time-warped box that runs without ntpd. Or play with TZ.

If whatever you're using DOES NOT use UTC, but calls libc localtime, then you can create a custom timezone. POSIX compliant systems are required to have ways to set timezones with almost any offset from UTC. Start all of your regressions in the special timezone. How you set up your timezone is totally system dependent (POSIX allows for three methods), but you should be able to accomplish this with TZ variable alone.

example my ZZT timezone:

Code:

$> export TZ=ZZT6:30:22
$> date
Thu Sep 27 07:25:51 ZZT 2007
$> export TZ=CST6CDT
$> date
Thu Sep 27 08:56:34 CDT 2007

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