&gt; Will do the same thing, and give an accurate % complete progress bar.<p>I&#x27;m not sure that&#x27;s true, last time I tried to do:<p><pre><code>  pv &lt; &#x2F;dev&#x2F;zero &gt; &#x2F;dev&#x2F;sda
</code></pre>
To zero a drive, it correctly printed out the total size of the output block device. Perhaps it also does this type of scanning on stdin, if possible.<p>That said, looking at the main page, it appears that this functionality is only available for the output end:<p>Note that if the input size cannot be calculated, and the output is a block device, then the size of the block device will be used and pv will automatically stop at that size as if -S had been given. (<a href="http:&#x2F;&#x2F;www.ivarch.com&#x2F;programs&#x2F;quickref&#x2F;pv.shtml" rel="nofollow">http:&#x2F;&#x2F;www.ivarch.com&#x2F;programs&#x2F;quickref&#x2F;pv.shtml</a>)