keeping something in memory after the end of script

swissknife has asked for the wisdom of the Perl Monks concerning the following question:

Dear Experts,

I am writing a script to monitor the change in checksum of a file. idea is to get the checksum id and store it somewhere and then in next run compare it with previously stored value and if difference alert it to Admin.

A simple solution is using file handling but what if someone change the content of this file once the new checksum is created.

So i was wondering is there a way to store this value directly in memory or somewhere more secure and then read it for comparison.

Thank You.

Comment on keeping something in memory after the end of script

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Re: keeping something in memory after the end of script by Corion (Patriarch) on Apr 15, 2016 at 10:41 UTC
There is no way to keep data "in memory" without also having a process attached to it. You will either have to stick the data into a file or into some kind of database. If you want to be notified of file changes, keep a process running and look at the inotify modules.	[reply]
Re: keeping something in memory after the end of script by BrowserUk (Patriarch) on Apr 15, 2016 at 11:30 UTC
On Windows you might consider the registry (via Win32::Registry). With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday' Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". I knew I was on the right track :) In the absence of evidence, opinion is indistinguishable from prejudice.	[reply]
Re: keeping something in memory after the end of script by clueless newbie (Curate) on Apr 15, 2016 at 10:58 UTC
You could send it to and retrieve it from a clipboard.	[reply]
Re: keeping something in memory after the end of script by NetWallah (Canon) on Apr 15, 2016 at 17:46 UTC
If the "Next run" is started from the same shell, or a child of that shell, you could use "export"ed environment variables to persist data, as suggested here. This is not an optical illusion, it just looks like one.	[reply]
Re^2: keeping something in memory after the end of script by fullermd (Vicar) on Apr 15, 2016 at 18:38 UTC
Not really (at least, not without some sort of nutso magic trick). The shell would be the parent process of your script; you can't mess with your parent's environment.	[reply]
Re^3: keeping something in memory after the end of script by NetWallah (Canon) on Apr 16, 2016 at 00:32 UTC
Point taken (++), but the magic is not too achene: `~$ chksum=$(perl -e'print qq\|Set by perl\|'); echo BASH says chksum is +$chksum BASH says chksum is Set by perl` [download] This is not an optical illusion, it just looks like one.	[reply] [d/l]