tac — Concatenate and Print files in reverse order.
Summary:
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).
Example:
$ 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