in reply to Re^5: scripting tar
in thread scripting tar

Well as far as modifying permissions and basic sys admin tasks, yes, shell is easy. I would tend to agree, it does have its limitations though. I was just hoping for an example of one of those limitations being done better in Perl.

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Re^7: scripting tar
by zentara (Cardinal) on Feb 01, 2009 at 14:58 UTC
    Well as I was dreaming last night, I felt bad about not answering better. So I thought up a typical real world problem that one might face.

    The problem:

    You must search thru a list of subdirs, defined by a specific alpha-numeric pattern. In each of those subdirs, you must locate a specific file (defined by another alpha-numeric pattern), and search thru that file for a specific name(s), given on the commandline as options. You must include logic to account for abbreviation of the middle initial/name. When you find those names, extract an account number, and save them. Next, go to another list of subdirs( as defined by another alpha-numeric pattern) and search all files for that account number. If that account number(s) is found, add the file to a backup tarball, then delete the account number from the file, and save the resulting file to another tarball, in a directory named based on the account number. The tarballs cannot exceed 500 megs, and must named sequentially. When done with 1 in a sequence, transfer it thru SFTP to another computer, and email the account manager.

    :-)

    Now, I'm sure that this can be done with a multi-line shell script full of pipes , sed, % signs, echo, and grep; but you would need one heck of alot of shell expertise, and most people would not be able to follow it's logic, with all the pipes.

    In Perl however, a clear script could be written, with intermediate arrays available for debugging printouts, etc.

    I will concede that shell can be faster and simpler for some simple operations, BUT in general, it is hard to follow, and full of hard_to_decipher option lists and pipes, for most real world tasks. Sure, just recursively tarring up a directory is simple with the shell, but it's the other things that are usually needed, that cast shadows over shell and make Perl shine.


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