Attempts to read
LENGTH bytes of data into variable
SCALAR from the specified
FILEHANDLE. Returns the number of bytes actually read, or undef if there was an error.
SCALAR will be grown or shrunk to the length actually read. An
OFFSET may be specified to place the read data at some other place than the beginning of the string. This call is actually implemented in terms of stdio's fread call. To get a true read system call, see sysread().