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tail    display lines towards the bottom of the file
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tail is a useful utility, especially if you are keeping tabs on a 
process that is producing output.

$ tail -n 5 file1   #display last 5 lines of file1
$ tail -5   file1   #further simplified
$ tail      fiele1  #default last 10 files (default value)

$ tail -f    /var/log/messages #monitor "messages" file
$ tail -f /tmp/debug.log --pid=2575  #stop monitoring when program ID 2572 finishes

$ tail -n +2 file1  #display lines in file1 starting at 2
                    #useful for skipping header
$ tail -r file1     #display files in reverse order (first line last etc)