Tac - A command to print files in reverse

Probably one of the very first commands we come across while learning Linux/Unix is “cat”. It is used to concatenate multiple files and throw them all on the standard output i.e. print them on a terminal. Not many know this, but there exists a twin of cat, named “tac”, which is similar to it but does everything in reverse - kind of an “evil twin” ;).

Here is a simple example. Lets say we have a file with the following contents(this is usually what we use cat for).

[shredder12]$ cat file

line 1
line 2

now tac will do exactly the reverse

[shredder12]$ tac file

line 2
line 1