The biggest problem in your parsing is recognizing the end of one run, because in your specification, a line with stars may either be the end of the current session, or perhaps the beginning of the next one because the current session was not ended properly. So any algorithm that doesn't reinterpret the meaning of a star-line in the context of the following line is doomed to fail.

This smells like a perfect job for Parse::RecDescent. The grammar will look something like (warning: UNTESTED): 

file: report(s?) /\Z/ { return $item[1] }
report: complete_report | incomplete_report
complete_report: star_line server_started data_line(s?) server_closed 
+star_line
  { return ["complete:", @item[2,3,4]] }
incomplete_report:  star_line server_started data_line(s?) server_clos
+ed(?)
  { return ["incomplete:", @item[2,3]] }
star_line: "*****\n"
server_started: "Server Started" /.*\n/ { "@item[1, 2]" }
server_closed: "Server Closed" /.*\n/ { "@[item[1, 2]" }
data_line: ...!(star_line | server_started | server_closed) /.*\n/

[download]
The result will be an array ref like: 
[
  ["complete:", "Server Started Monday", ["data1", "data2", "data3"], 
+"Server Closed Thursday"],
  ["complete:", "Server Started Tuesday", ["data1", "data2", "data3"],
+ "Server Closed Thursday"],
  ["complete:", "Server Started Wednesday", ["data1", "data2", "data3"
+], "Server Closed Thursday"],
  ["incomplete:", "Server Started Monday", ["data1", "data2", "data3"]
+],
  ["complete:", "Server Started Monday", ["data1", "data2", "data3"], 
+"Server Closed Thursday"],
]

[download]
Hopefully, you can read up enough on Parse::RecDescent to figure out how to use this grammar and invoke it. If I get time, I'll write this up completely and repost it. Actually, it looks like a nice potential future Linux Magazine article. Thanks for the idea! </code>

-- Randal L. Schwartz, Perl hacker

In reply to Re: Multiple session log extraction from a single file problem by merlyn
in thread Multiple session log extraction from a single file problem by dmtelf

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