tail

End of file

Get the last 10 lines of a file.

$ tail file.txt

Get the last 100 lines of a file.

$ tail -n 100 file.txt

Follow

This command will watch continuously for output and not exit.

$ tail -f

Or

$ tail -f > /dev/null

Selection

Get lines 300 to 450 of a file.

$ head -n 450 file.txt | tail -n 150