That could work, but there are a few potential issues.  'tail' does slightly different stuff on different platforms.  Maybe you're on Windows and it isn't available.  Maybe it mangles your output (I know that some coreutils tools try to be encoding-aware, I don't know if 'tail' is one).  Maybe you want to get blocks of bytes off the end rather than lines, etc.  Then you also need to worry about housekeeping for a subprocess, which always turns out to be a little trickier than you first expect.