code>end</code> of the file, with the
byte at position <code>end</code> not included. If no arguments are
specified, the full file is locked, If only <code>start</code> is specified
the file is locked from byte position <code>start</code> to the end of the
file, no matter how large it grows. It is possible to specify an
explicit value of <code>end</code> which is past the current length of the file.</p>
<p>To obtain an exclusive lock on a file it must be opened for writing.</p>
<p>If <code>mode</code> is <a