|Perl: the Markov chain saw|
changing a portion of a line leaving its formatting intactby bronto (Priest)
|on Dec 14, 2004 at 15:16 UTC||Need Help??|
bronto has asked for the wisdom of the Perl Monks concerning the following question:
I am building an application that should read and collect data from many NetApp filers and store them in a database for making periodical usage reports. To avoid bothering production filers during the early stage of development I created a file for each filer containing the output of the quota report command.
The output looks like:
To simulate the command output, I'd need to read the file line by line, print if it doesn't begin with tree, otherwise substitute the fifth field (say: $field with int rand $field). Since the dashed line on top of the report gave me an hint for creating a sprintf format, I found that this one-liner just does the job I need:perl -pe 'next unless /^tree/ ; @f=split ; $f = int rand $f ; $_ = sprintf "%-5s %8d %-8s %-8s %8d %8d %7d %7d %-15s\n",@f' filer.quota.report
But what if I hadn't any hint? How would you replace the fourth field leaving the line formatting in a sane state?
Thanks in advance for your suggestions
In theory, there is no difference between theory and practice. In practice, there is.