storing variable value
d.dalton at iinet.net.au
Tue Apr 14 05:34:39 CEST 2009
Yes. I used a file, thanks.
On Sat, Apr 11, 2009 at 09:30:40AM -0400, Dave Angel wrote:
> Daniel Dalton wrote:
>> I'm writing a program to provide me with battery warnings when my
>> battery hits certain levels. It just checks the current level and does
>> something. I plan to call it from a a cron job. But If the cron runs
>> every minute, warnings every minute would be rather annoying. so is
>> there a way to make the script check if it has already ran before?
>> eg. can I write to a variable on one run of the program, and on the next
>> read that value that was written?
> To put it simply, you want to store a value from one run of the script,
> that persists till the next run of the same script.
> The most portable way to to that is to write a file. And since all you
> care about is the time of writing, the file can be zero length. So
> simply check for the file, determine it's creation time, and decide if
> it's too recent to want to run again. If the file doesn't exist, or is
> "old", then write the file and notify the user.
> It's still messy to leave this bogus file around, so think carefully
> about where to put it. If the source directory is writable, it's
> reasonble to me to simply put it there. That way, if the program gets
> deleted, it'll probably get deleted at the same time. Failing that, you
> could put it in a TEMP directory. And perhaps the sneakiest place to
> put it, if you're on Windows, is in the "run once on startup" directory.
> Make it a do-nothing batch file, and Windows will remove it next time the
> user restarts the system.
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