in reply to Sorting and subsituting a data file, one pass

Go through your data file line by line, assembling your data -start <string> -end <string> as you go along. Once each item is assembled store it as the key of a hash (the value can be anything you like or left empty). Duplicate hash keys will disappear automatically and you can then sort the keys.

CountZero

A program should be light and agile, its subroutines connected like a string of pearls. The spirit and intent of the program should be retained throughout. There should be neither too little or too much, neither needless loops nor useless variables, neither lack of structure nor overwhelming rigidity." - The Tao of Programming, 4.1 - Geoffrey James

In Section Seekers of Perl Wisdom