Flip a YAML file content so that the newest lines are top

Question

I have a YAML file with thousands of lines of text in it, and I want the most recent lines added to appear on the very top of the file and the oldest contents to be at the very bottom of the file, so that when I open the file I don't have to scroll down for 5 minutes to get to the bottom to be able to read the new content.

#current structure        #desired structure
1: oldest line            4: newest line
2: old line               3: new line 
3: new line               2: old line
4: newest line            1: oldest line

You can use the `tac` command in `bash` to print the lines in reverse order — Saswat Padhi, Sep 12 '19 at 14:00

Gilles Quénot · Answer 1 · 2019-09-12T14:31:11.773

-1

One solution, taking care of comments :

Command

head -1 file; awk 'NR>1' file | sort -nr

Output

#current structure
4: newest line
3: new line       
2: old line       
1: oldest line

Finally to overwrite file

head -1 file; awk 'NR>1' file | sort -nr | tee file

(works for small files.)

For big files :

 head -1 file; awk 'NR>1' file | sort -nr > temp$$
 mv temp$$ file

edited Sep 12 '19 at 14:31

answered Sep 12 '19 at 14:04

Gilles Quénot

173,512
41
224
223

This doesn't rewrite the file, it just outputs the content of the file upsidedown in the terminal. – Saber Sep 12 '19 at 14:17
So, do you know Unix redirections ? I will add it – Gilles Quénot Sep 12 '19 at 14:28
running this command it only re adjust the content once. But when i run it again i was expecting that the file gets re adjusted back to its original state. however it doesn't. – Saber Sep 12 '19 at 15:51
I have very less UNIX experience – Saber Sep 12 '19 at 15:52
Always use backups. My snippet do exactly what you asked. I would like the one that voted down to know the reason – Gilles Quénot Sep 13 '19 at 10:59

Flip a YAML file content so that the newest lines are top

1 Answers1

Command

Output

Finally to overwrite file