why graphviz dot can not open a dot file?
<p>I am compiling a dot file to a jpg using dot program about graphviz.This is my command:</p>

<pre><code>dot a.dot -o 1.ps
</code></pre>

<p>The out put error is:</p>

<pre><code>Error: dot: can't open a.dot
</code></pre>

<p>This is my dot file(a.dot) content:</p>

<pre><code>digraph abc{
  a;
  b; 
  a -&gt; b; 
}
</code></pre>

<p>I have tried:</p>

<pre><code>dot -Tjpg -Gdpi=331 a.dot -o a.jpg
dot -Tps a.dot -o a.ps
</code></pre>

<p>Why would this happen? How to fix?</p>

<p>OS:Windows 7 X64</p>

<p>dot version: dot - graphviz version 2.38.0 (20140413.2041)</p>