linux grep command with file name that exist
<p>I am new to Linux. When I typed <code>grep filename</code> and pressed <kbd>enter</kbd>, it showed a blank line with cursor and I had to press <kbd>ctrl</kbd>+<kbd>z</kbd> or <kbd>ctrl</kbd>+<kbd>c</kbd> to exit. Shouldn't it be showing me some kind of error that command is not complete? In short, what is happening after I type <code>grep filename</code> and pressed <kbd>enter</kbd>.</p>

<p><a href="http://i.stack.imgur.com/ostGl.jpg" rel="nofollow">Here is my commands</a></p>