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Re^3: Use a Variable in a Separate Perl Script

by rovf (Priest)
on Jun 08, 2012 at 09:37 UTC ( #975126=note: print w/ replies, xml ) Need Help??


in reply to Re^2: Use a Variable in a Separate Perl Script
in thread Use a Variable in a Separate Perl Script

$final is defined by user input, so it is always dynamic.
Well, variables are always dynamic, that's why they are called variables.

Some of the confusion in the replies to your question seem to be caused by the term "script", which you are using. My understanding is, that script1 and script2 MUST be separate process, in the sense of independent commands, and you need to pass information from one script to the other. Is this correct?

Some replies to your question imply that there is a closer coupling of the script possible (so that you can run the whole code within a single process). Both approaches make sense, but maybe you should explain more in detail what your requirements are. Only then can we propose a better solution. Also it helps if you explain, what kind of value $final is supposed to have. Proposed solutions might be slightly different, dependent on whether this value, for instance, is supposed to be a one-digit number, or the content of a whole Word document...
-- 
Ronald Fischer <ynnor@mm.st>


Comment on Re^3: Use a Variable in a Separate Perl Script
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Re^4: Use a Variable in a Separate Perl Script
by NinjaOne (Initiate) on Jun 08, 2012 at 12:22 UTC
    Good point. You are correct, Script1 and Script2 are separate processes. At the completion of Script1, I have a mini Bash script (cd <into directory>, ./script2.pl) which executes Perl Script2. I need Script2 to recognize the $final variable defined from Script1. Is this possible? $final will be given a name, such as "Basketball". So I need Script1 to attain the variable (from user input). Then once Script2 is executed, which is completely separate from Script1, it will be able to use the given variable of "Basketball" and continue with the actions of Script2.
      OK, so let's clarify: Since you have two completely unrelated processes (unrelated from the Perl- OS-viewpoint), it doesn't make sense to talk about "one script refering to a variable in another script". However, it makes sense to pass a value to the other script. Now, your case is a bit more complicated because you don't execute the other script directly, but have a bash process in between.

      Of course, this bash process is unnecessary, if all it does is to do a chdir. You can do the chdir in Perl as well (see chdir). However, if you expect that this intermediate bash script later will do additional stuff, which you, for whatever reason, would prefer implementing in bash, it would make sense to stick with that.

      As for passing the value of your variable to the other script, you have several options. Since in your case, the value is only a fairly short string, I would consider two possibilities: Pass them as a parameter to your bash script, which then hands it over as a parameter to your Perl script; or use an environment variable to pass the information.

      The latter solution is faster (simpler) to implement, but the former one is, IMO, cleaner.
      -- 
      Ronald Fischer <ynnor@mm.st>

        Again, sorry for not being more clear in my description. You all make very valid points.

        The reason I have two Perl scripts, is because they will executed at different times. Some background information through an example:

        User executes PerlScript1. This creates a directory with contains a Checklist and a small bash script. The reason the bash script isn't executed yet is because it will execute PerlScript2, which produces a timestamped file that contains updates (only as recent as the timestamp, which is why I delay PerlScript2 by means of the bash script. This way the user can complete and add to the Checklist document and they don't have to worry about executing the second Perl script until they are absoultey ready, so as to ensure they have the most current updates.) When the user is finally ready for the timestamped folder, they can execute the bash script, which will call upon PerlScript2 and execute it, thus creating an updated timestamped folder. PerlScript2 sends out an email notification when it is executed and ultimately needs to use the $final variable from PerlScript1 to populate the email with the correct filename given in PerlScript1.

        Hope this helps fill in some of the gaps.

        Thanks.

      This depends on whether the bash script is being executed by script1.pl, or by some other parent process which runs script1.pl, waits for it to complete, then runs the bash script. In the first case, simply pass the value in the command line like I did in my example, and then do the same from within your bash script. In the latter case, script1.pl would need to return the value to its parent process, which would then pass the value to the bash script.

      I think it's very likely that the best solution would be to redo the whole thing as a single Perl script. However, if you already have two Perl scripts and you're just hoping to pass a value from one to the next without making any other changes, use my example, except stick chdir "directory"; at the beginning of script2.pl. That will eliminate the need for a bash script sitting between the two.

      Aaron B.
      Available for small or large Perl jobs; see my home node.

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