Reversing the contents of a file

The command cat is used to view the contents of a file with out opening it, the contents are displayes from top to bottom in the usual way. In case you want to view the contents in the reverse that is from last line to first here are a few ways to do it.

Let us say we have a file named test with the following contents

test :

The best way to make your dreams come true is to wake up Modest doubt is called the beacon of the wise We're all just walking each other home Make no judgements where you have no compassion You must be the change you wish to see in the world Love is the way messengers from the mystery tell us things In order to learn the art of dying , one must know completely the art of living A poem should not mean. But be Love all, serve all, feed all If you want to be a rebel, be kind

1. tac

The command tac takes a filename as input and displays the contetns in the bottom up fashion.

$ tac test If you want to be a rebel, be kind Love all, serve all, feed all A poem should not mean. But be In order to learn the art of dying , one must know completely the art of living Love is the way messengers from the mystery tell us things You must be the change you wish to see in the world Make no judgements where you have no compassion We're all just walking each other home Modest doubt is called the beacon of the wise The best way to make your dreams come true is to wake up

2. Using awk :

The following awk script takes a file name as input and displays the same in the reverse order .

$ awk 'BEGIN{i=0} { lines[i++]=$0 } END{for(i=NR;i>=0;i--){ print lines[i]} }' test If you want to be a rebel, be kind Love all, serve all, feed all A poem should not mean. But be In order to learn the art of dying , one must know completely the art of living Love is the way messengers from the mystery tell us things You must be the change you wish to see in the world Make no judgments where you have no compassion We're all just walking each other home Modest doubt is called the beacon of the wise The best way to make your dreams come true is to wake up

3. Using sed :

The following sed script takes a file name as input and reveres the contents, displaying it from bottomt to top.

$ sed -ne '1!G' -e 'h' -e '$p' test If you want to be a rebel, be kind Love all, serve all, feed all A poem should not mean. But be In order to learn the art of dying , one must know completely the art of living Love is the way messengers from the mystery tell us things You must be the change you wish to see in the world Make no judgements where you have no compassion We're all just walking each other home Modest doubt is called the beacon of the wise The best way to make your dreams come true is to wake up