unix redirect tail to file
I am waiting for your confirmation to my previous comment. But in the meantime, I am going to assume the affirmative and give you a suggested solution.
Placing a ! at the end of the > or >> redirects will turn off the default "noclobber" switch that prevents overwriting an existing file:
tail -f -n1 amroutput >! amr_lastoutputIf this does not work for you, let me know and we can try something else.