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Log file analysis
Input / Output example from a Well House Consultants training course
More on Input / Output [link]
Source code: loganal Module: U110
--[[
Reads a web access log file ... breaking each line down into a series of space separated fields in a table. In this example, all that we have done with the data is then to identify and count the number of unique values in the first column; with the web server log file we used, this means that we counted the number of times each different client called up a page. ]] fh,err = io.open("../mx/data/access_log.xyz") if err ~= nil then print (err) return end lynes = 0 all = {} counters = {} while true do stuff = fh.read(fh) if stuff == nil then break end lynetab = {} for i in string.gmatch(stuff,"(%S+)") do lynetab[#lynetab+1] = i -- print (i) end all[#all+1] = lynetab host = lynetab[1] if counters[host] == nil then counters[host] = 0 end counters[host] = counters[host] + 1 -- print (stuff) lynes = lynes + 1 end print ("There are",lynes,"lines") -- Output a table of the visiting clients, and the hit count for each for k,v in pairs(counters) do print (string.format("%-10s %4d",k,v)) end -- Now output the same list again, but sorted. -- You need to make up an indexed table of the keys ktab = {} for k,_ in pairs(counters) do ktab[#ktab+1] = k end -- and define how the records are to be compared (unless -- you want a default sort of the keys) function myway(x,y) if counters[x] < counters[y] then return true end return false end table.sort(ktab,myway) for _,v in ipairs(ktab) do print (string.format("%-10s %4d",v,counters[v])) end --[[ Sample output ------------------------------------ [trainee@easterton nts]$ lua loganal There are 6912 lines dolphin 11 magnet 312 mussel 232 tuna 61 aviemore 318 plaice 61 lecht 26 whale 1044 localhost 1 whiting 2 whelk 1 manatee 1 dab 1 seaweed 4 Wed 1 dogfish 22 walrus 310 o_whelk 458 seal 313 trout 302 skate 1995 perch 391 clam 45 catfish 5 pilchard 1 sardine 348 flipper 322 sealion 324 localhost 1 manatee 1 whelk 1 Wed 1 dab 1 pilchard 1 whiting 2 seaweed 4 catfish 5 dolphin 11 dogfish 22 lecht 26 clam 45 tuna 61 plaice 61 mussel 232 trout 302 walrus 310 magnet 312 seal 313 aviemore 318 flipper 322 sealion 324 sardine 348 perch 391 o_whelk 458 whale 1044 skate 1995 [trainee@easterton nts]$ ]] 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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