Name

tail [OPTION]... [FILE]... 

-c, --bytes=N
      output the last N bytes
-f, --follow[={name|descriptor}]
      output appended data as the file grows; -f, 
      --follow, and --follow=descriptor are
      equivalent
-n, --lines=N
      output the last N lines, instead of the last 10 

for f in $( ls /var/ ); do echo $f; done | nl > file1 

By default a tail command displays last 10 lines of given file.

tail 

To display just last 3 lines from this file we use -n option:

tail -n 3 file1 

Moreover the same output can be produced by command:

tail -3 file1 

To use tail command on byte level we can use -c option. This option will make tail command to display last 4 bytes (4 characters) if a given file:

tail -c 4 file1 

If you wonder why we can see only 3 characters, use od command to see where the 4th byte is:

tail -c 4 file1 | od -a 

Another very useful option for tail command is -f. This option will continuously display a file as it is dynamically edited by another process. This option is very useful for watching log files.

tail -f /var/log/syslog