f:read

v1, v2 ... = f:read (format1, format2, ...)

Reads the file f according to the given formats. Each format returns a string, a number, or nil and an error code if it fails (see below). The formats are:

• *n - reads a number and returns it
• *a - reads the entire file from the current position
• *l - (default) - reads the next line, returns nil on EOF
• number - returns a string with up that many characters in it, or nil on EOF

f = io.input ("test.txt")
repeat
  s = f:read ("*l") -- read one line
  if s then  -- if not end of file (EOF)
   print (s) -- print that line
  end
until not s  -- until end of file

f:close ()  -- close that file now

If the file cannot be read the function returns 3 things:

• nil
• An error message (string)
• An error code (number)