You might wonder 'how do I get the last lines of a log file' or 'how do I get new lines written to a file in linux'. Well tail is what you need!
Tail is a program which Outputs a number of lines from a file depending on what arguments you call it with. There are quite a few arguments you can add but the core what is useful is below.
You can invoke tail but where it really shines is in a pipe operation.
./someFile.txt | tail -n 5
./someFile.txt | tail -f
|-f||follow||output new lines on the end|
|-F||follow and retry||follow and retry if the file is inaccessible|
|-n #||number||number of lines to output when the command is run|
|+ #||number of lines to output at the start of the file|
|- #||number of lines to output at the end of the file|