sed remove match and next lines

Question

Not sure why my RedGex expression not working, I'm trying to ommit match and next lines

[example.com]
10.0.0.1 
10.0.0.2
[example.net]
10.0.0.10
10.0.0.20

Desired output

[example.net]
10.0.0.10
10.0.0.20

Here is what I have tried so far, but it matches more lines than desired

   sed -e '/(\[example.com\])(.*\n)+/d'

is the number of lines to delete after matching `[example.com]` fixed or variable? — Sundeep, Nov 13 '16 at 12:00
so, you want to delete from line matching `[example.com]` upto but not including next line matching `[example.*]`? — Sundeep, Nov 13 '16 at 12:24
You are correct, [example.com] and following lines should be deleted, however [example.net] should remain — Deano, Nov 13 '16 at 12:26

score 2 · Answer 1 · edited May 23 '17 at 12:01

I think awk is more suited for this task

$ awk '/\[example.com\]/{f=1; next} /\[example.*\]/{f=0} !f' ip.txt 
[example.net]
10.0.0.10
10.0.0.20

/\[example.com\]/{f=1; next} if line matches [example.com] set a flag f and move on to next line
/\[example.*\]/{f=0} if line matches \[example.*\], unset the flag
!f print lines if flag is not set

With sed, the best I could do is using this answer

$ sed '/\[example.com\]/,/\[example.*\]/ { /\[example.com\]/d; /\[example.*\]/!d }' ip.txt 
[example.net]
10.0.0.10
10.0.0.20

score 1 · Answer 2 · answered Nov 13 '16 at 15:23

This might work for you (GNU sed):

sed -n '/^\[[^]*\]/h;G;/\n\[example.com\]/!P;d' file

On encountering a line(s) you don't want to match, store said line in the hold space (HS), append it to the pattern space (PS) and only print current line if the second part does not contain the required string.

score 1 · Accepted Answer · answered Nov 13 '16 at 20:44

sed is for simple subsitutions on individual lines, that is all. For anything else you should be using awk for every desirable attribute of software (efficiency, clarity, robustness, portability, maintainability, etc., etc.):

$ awk '/^\[/{f=/\[example\.com\]/} f' file
[example.com]
10.0.0.1
10.0.0.2

$ awk '/^\[/{f=/\[example\.com\]/} !f' file
[example.net]
10.0.0.10
10.0.0.20

sed remove match and next lines

3 Answers3