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Finding the latest log file and analysing it (popen, ls)
Input / Output example from a Well House Consultants training course
More on Input / Output [link]
Source code: filescan Module: U110
--[[
This example looks though all the files in our log file directory and finds the most recent log files (our log files are automatically named ac_ followed by the date on which they were created ]] -- Use the operating system's commands to parse a directory stream = io.popen("ls ../data","r") while true do line = stream:read() if not line then break end year, month, day = string.match(line,"ac_(%d%d%d%d)(%d%d)(%d%d)") if year then -- print (day .. "/" .. month .."/" .. year .."\n") lastest = line end end -- Parse the last data file that matched fh = io.open("../data/" .. lastest) problem = {} while true do line = fh:read() if not line then break end -- here is a sample data line (some line breaks added for clarity) -- 71.205.187.35 - - [27/Jul/2009:03:30:27 +0100] -- "GET /resources/ex.php4?item=http://owned-nets.blogspot.com/ -- 2009/05/pro0f3th1sddbluelinebe.html? HTTP/1.1" 200 12555 "-" -- "Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.0.9) -- Gecko/2009040821 Firefox/3.0.9" -- Extract the needed fields from the access log line. -- note the use of the ".-" count in pattern matching - the -- equivalent of ".*?" in regular expressions, meaning that -- we are matching as few characters as possible, rather than -- as many as possible. So we are moving up to the NEXT double -- quote character, and not to the LAST double quote, in this next line ip, request, status, size = string.match(line, "^(%S+).-\"(.-)\"%s+(%S+)%s+(%S+)") statuscode = tonumber(status) -- trap non-numeric value in status code first -- the lazy and operator allows this to be done as a single -- test, with no worry that the program will crash if the -- status code wasn't a number if statuscode and statuscode >= 400 then print (ip, status, size) problem[#problem+1] = {ip, status, size} end end Learn about this subject
This module and example are covered on the following public courses:
* Learning to program in Lua * Lua Programming * Lua Programming Also available on on site courses for larger groups Books covering this topic
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Other Examples
This example comes from our "Input / Output" training module. You'll find a description of the topic and some
other closely related examples on the "Input / Output" module index page.
Full description of the source code
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