), <code>fcntl()</code> will wait (block) until the lock has cleared, then will set it itself. This is a very useful command. I use it all the time.| |<code>F_SETLK</code>|This function is almost identical to <code>F_SETLKW</code>. The only difference is that this one will not wait if it cannot obtain a lock. It will return immediately with <code>-1</code>. This function can be used to clear a lock by setting the <code>l_type</code> field in the <code>struct flock</code> to <code>F_UNLCK</code>.| |<code>F_G