Title: Fun tip #3: Split a line using ed | |
Author: Solène | |
Date: 04 December 2018 | |
Tags: fun-tip unix openbsd | |
Description: | |
.Dd December 04, 2018 | |
.Dt "Splitting a line using ed" | |
In this new article I will explain how to programmaticaly | |
a line (with a newline) using ed. | |
We will use commands sent to ed in its stdin to do so. The logic is to | |
locate the part where to add the newline and if a character need to be | |
replaced. | |
.Bd -literal -offset indent | |
this is a file | |
with a too much line in it that should be split | |
but not this one. | |
.Ed | |
In order to do so, we will format using printf(1) the command list | |
using a small trick to insert the newline. The command list is the | |
following: | |
.Bd -literal -offset indent | |
/too much line | |
s/that /that\ | |
,p | |
.Ed | |
This search the first line matching "too much line" and then replaced | |
"that " by "that\n", the trick is to escape using a backslash so the | |
substitution command can accept the newline, and at the end we print | |
the file (replace ,n by w to write it). | |
The resulting command line is: | |
.Bd -literal -offset indent | |
$ printf '/too much line\ns/that /that\\\n\n,n\n' | ed file.txt | |
81 | |
> with a too much line in it that should be split | |
> should be split | |
> 1 this is a file | |
2 with a too much line in it that | |
3 should be split | |
4 but not this one. | |
> ? | |
.Ed |