Running external un-zip executable with io.popen() call

Sometimes we have to execute external executable from within Lua script.

For example, you received zip file zipped in 7-Zip and you wish to unzip using very same program 7-Zip.

In order to unzip it, there is need to use external executable 7-Zip from ‘7-Zip Command Line Version’ .

Below is quick simple code demonstrating how to do it:

function main ()
 local e = '\"C:/7za920/7za.exe\" \" e -y -oC:/temp/7zipOut C:/7za920/a.zip\"'
 local E = io.popen(e)
 local out = E:read('*a')
 io.close(E)
end

Paths:

– 7zip is installed in c:\7za920 (it is ‘7-Zip Command Line Version’ for Windows downloaded from http://www.7-zip.org/download.html)

– Files from zip extracted into output folder c:\temp\7zipOut

– Archive a.zip is located in C:\7za920 folder

This creates a bunch of files in output folder.

Then we can use io.popen() to list extracted files into List of Files and process them one by one in a loop.

require('files')
 
function main ()
 
   local e = '\"C:/7za920/7za.exe\" \" e -y -oC:/temp/7zipOut C:/7za920/a.zip\"'
   local E=io.popen(e)
   local out=E:read('*a')
   io.close(E)
 
   local P = io.popen('dir /b c:\\temp\\7zipOut\\*.txt')
   local List = P:read('*a')
 
   for k, v in pairs (List:split('\n')) do 
      local f=io.open('c:\\temp\\7zipOut\\'..v,'r') 
 
      if (f) then  
         local s=f:read("*all")  
         queue.push{data=s}
         io.close(f) 
      end 
   end
end

Note: we call function string.split() defined elsewhere, e.g. http://wiki.interfaceware.com/534.html