sysread

Reads maxlen bytes from ios using a low-level read and returns them as a string. Do not mix with other methods that read from ios or you may get unpredictable results. If the optional outbuf argument is present, it must reference a String, which will receive the data. The outbuf will contain only the received data after the method call even if it is not empty at the beginning. Raises SystemCallError on error and EOFError at end of file.

f = File.new("testfile")
f.sysread(16)   #=> "This is line one"