Time Calculations

Nysif Steve · #1 (**permalink**) 09-13-2007

I'm trying to have a loop print out statistics every X number of seconds. How can I add a specific number of seconds to a time variable and make a comparison? Thanks ahead of time.

For example:

Code:


startTime = `date +%H%M%S`
currentTime = $startTime
executeTime = startTime + X   # X is equal to the number of seconds
until(( $currentTime >= $endTime))
do
     if (($currentTime = $executeTime))
     then
          .
          .
          .
          ((executeTime = $currentTime + X ))  # X is equal to the number of 
     fi

     currentTime = `date +%H%M%S`
done

jim mcnamara · #2 (**permalink**) 09-13-2007

In general, when working with time like this, you convert current time(s) to the epoch time in seconds - ie. number of seconds since Jan 1 1970.
On linux (or if you have gnu date)

Code:

epoch_seconds=$(date +%s)

otherwise try perl

Code:

epoch_seconds=$(perl -e 'print time;')

epoch_seconds is now a number like 1189706758 that you can add seconds to.

Nysif Steve · #3 (**permalink**) 09-13-2007

date +%s prints %s to the screen

Nysif Steve · #4 (**permalink**) 09-13-2007

I ran the man command on the date function. It doesn't seem to have an option for epoch time. What you suggested sounds like it'd fit what I am trying to do perfectly. How do I check the version on the date function currently in place? Could it possibly be a different flag besides %s?

Perderabo · #5 (**permalink**) 09-13-2007

As Jim mentioned, %s is an extention only available on gnu sed. He also mentioned perl which may be a better option. Please tell us what OS you have so we don't have to guess which tools you have.

Nysif Steve · #6 (**permalink**) 09-14-2007

The perl -e command is working. Thank you for your help.

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