tac — Concatenate and Print files in reverse order.
tac copies each file to standard output, reversing the records (lines by default) in each separately. It is doing the reverse function of the CAT command (TAC).
$ tac myfile — Print the file (Line by Line) in reverse order.
$ tac -r -s ‘[^a-zA-z0-9-]’ myfile — Print the file (Word by Word) in reverse order, by passing the Regular expression.
$ tac -r -s ‘.|’ myfile — Print the file (Char by Char) in reverse order.
Read: man tac
tac, cat, odoc, linux, gnu/linux