What does tac command do?

The tac command in Unix-like operating systems is used to concatenate and display the contents of files in reverse order. It reads the input file(s) line by line and outputs them starting from the last line to the first.

Usage:

tac filename.txt

Example:

If filename.txt contains:

Line 1
Line 2
Line 3

Running tac filename.txt will output:

Line 3
Line 2
Line 1

This command is useful when you want to view the last lines of a file first. If you have any more questions, feel free to ask!