linux - output changes on terminal when file changes

Question

In a open terminal how could I see all the new content added to a file whenever a process writes data into it?

I've tried combinations with cat and tee but no success

Answer 1

Use tail with -f

tail -f filename

Taken from the man pages for tail:

   -f, --follow[={name|descriptor}]
          output appended data as the file grows;

          an absent option argument means 'descriptor'