Re: Rewriting file from bash

[Davide Brini]

On Sun, 3 Oct 2021 17:16:04 +0200, Julius Hamilton
<juliushamilton100@gmail.com> wrote:

> Hey,
> 
> How could I print the nth region of text of a file that is between blank
> newline regions, at the command line? So for example:
> 
> file.txt:
> 
> line1
> 
> line2
> line3
> 
> line4
> 
> 
> 
> $ region[2]
> 
> would return
> 
> line2
> line3
> 
> I presume this would be with grep, sed and/or awk.
> 
> How could I then write a replacement for that region, from the command
> line (i.e. not using Vim or something)? Something like:
> 
> $ region [2] “this is the replacement line”

Not really a bash question, but here's a way with awk:

awk -v RS= -v repl="replacement\nlines" -v n=2 '
NR == n { $0 = repl }
{ print sep $0; sep = "\n"}
' file.txt

where the meaning of the "repl" and "n" varuables should be apparent.

-- 
D.