title: list the uniq lines based on ":" delimiter
body: <p>I am trying to write a script which will find the unique lines(first occurance) based on columns/delimiters. In this case to my understanding delimiter is ":".  </p>
  
  <h1>for example:</h1>
  
  <pre><code>May 14 00:00:01  SERVER1 ntp[1006]:  ntpd[Info]: 1430748797.780852: ndtpq.c(20544): this is the log  
  May 14 00:00:01  SERVER1 ntp[1006]:  ntpd[Info]: 1430748797.780853: ndtpq.c(20544): this is another log  
  May 14 00:00:02  SERVER1 ntp[1006]:  ntpd[Info]: 1430748798.780852: ndtpq.c(20544): this is another log  
  May 14 00:00:03  SERVER1 ntp[1006]:  ntpd[Info]: 1430748799.780852: ndtpq.c(20544): this is the log  
  May 14 00:00:04  SERVER1 ntp[1006]:  ntpd[Info]: 1430748800.780852: ndtpq.c(20544): this is the log  
  May 14 00:00:04  SERVER1 ntp[1006]:  ntpd[Info]: 1430748800.790852: ndtpq.c(20544): this is the log  
  May 14 00:00:05  SERVER1 ntp[1006]:  ntpd[Info]: 1430748801.790852: ndtpq.c(20544): thisis really different log  
  </code></pre>
  
  <h1>desired output:</h1>
  
  <pre><code>May 14 00:00:01  SERVER1 ntp[1006]:  ntpd[Info]: 1430748797.780852: ndtpq.c(20544): this is the log  
  May 14 00:00:01  SERVER1 ntp[1006]:  ntpd[Info]: 1430748797.780853: ndtpq.c(20544): this is another log  
  May 14 00:00:05  SERVER1 ntp[1006]:  ntpd[Info]: 1430748801.790852: ndtpq.c(20544): thisis really different log  
  </code></pre>
  
  <p>I am able to find the uniq log using the following command but ,I am loosing the timestamp by using this way. </p>
  
  <pre><code>cat fileName |awk -F: '{print $7}'
  </code></pre>