Tailf:
tailf will print out the last 10 lines of a file and then wait for the file to grow. It is similar to tail -f but does not access the file when it is not grow-ing. This has the side effect of not updating the access time for the file, so a filesystem flush does not occur periodically when no log activity is happening.
tailf is extremely useful for monitoring log files on a laptop when logging is infrequent and the user desires that the hard disk spin down to conserve battery life.
Example: # tailf /var/log/squid/access.log
Similarly you can watch the same log file using -f argument
Example: # tail -f /var/log/squid/access.log
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source:http://linuxpoison.blogspot.com/2009/11/135781757116461.html