title: Is there a Unix utility to prepend timestamps to stdin?
body: <p>I ended up writing a quick little script for this in Python, but I was wondering if there was a utility you could feed text into which would prepend each line with some text -- in my specific case, a timestamp.  Ideally, the use would be something like:</p>
  
  <pre><code>cat somefile.txt | prepend-timestamp
  </code></pre>
  
  <p>(Before you answer sed, I tried this:</p>
  
  <pre><code>cat somefile.txt | sed "s/^/`date`/"
  </code></pre>
  
  <p>But that only evaluates the date command once when sed is executed, so the same timestamp is incorrectly prepended to each line.)</p>