Question

Basically, I have several devices I need to pull data from. I get multiple emails when the temperature measures are under or over the set limits. I would like to have a for loop to include all current devices states that are under or over limits into one email.

body = for device_name, 1 do 
  device_name++ -- I get error here because unexpected symbol near 'for'
  "Device Name: " ..device_name.. "\nDevice Location: " ..device_location.. 
  "\n--------------------------------------------------------------" .. 
  "\nCurrent Temperature: " ..temperature.." F".. "\nTemperature Limit: ("..
  t_under_limit.. "-" ..t_over_limit.. " F)" .."\n\nCurrent Humidity Level: " .. 
  humidity .. "%".. "\nHumidity Limit: (" .. h_under_limit.. "-" ..h_over_limit.. "%)" 
  .. "\n\n-------Time Recorded at: " ..os.date().. "-------"})
end, -- end for

Answer 1

As previously noted, there is no ++ operator in Lua. Also, the syntax for the for loop is different from what you wrote.

I would like to add that the big concatenation afterwards would be much more readable using string.format. Here is an enhanced version of your code, in the form a a function taking a table devices parameters in input, each element being a subtable:

local report_model = [[
Device Name: %s
Device Location: %s
--------------------------------------------------------------
Current Temperature: %d °F
Temperature Limit: (%d-%d °F)
Current Humidity Level: %d %%
Humidity Limit: (%d-%d %%)

-------Time Recorded at: %s-------]]

function temp_report(devices)
  local report = {}
  for i=1,#devices do 
    local d = devices[i]
    report[i] = report_model:format(d.name, d.location,
      d.temperature, d.t_under_limit, d.t_over_limit,
      d.humidity, d.h_under_limit, d.h_over_limit,
      os.date())
   end
   return table.concat(report)
end