Re: sed N command with relative addressing

[Paolo Bonzini]

Il 16/05/2014 07:03, Hiroto Kagotani ha scritto:
> $ seq 1 10 | gsed '3,+3N; s/\n/-/'
> 1
> 2
> 3-4
> 5-6
> 7-8
> 9
> 10
> $ seq 1 10 | gsed '3,6N; s/\n/-/'
> 1
> 2
> 3-4
> 5-6
> 7
> 8
> 9
> 10
>
> `3,+3N' seems to be treated as `3,7N'.
> Is there any reason for the 2nd relative address to be relative to the
> next line of the 1st address only for N command?

Interesting.  This is because "+3" is treated as "3 evaluations of the 
address", for example:

$ seq 1 10 | sed -n '/[24680]/ {; 1,+3 p; }'
2
4
6

$ seq 1 10 | sed -n '/[24680]/ {; 5,+3 p; }'
6
8
10

$ seq 3 10 | sed -n '/[24680]/ {; /4/,+3 p; }'
4
6
8

I suspect this bug has been there forever, though I wouldn't be opposed 
to fixing it.

Paolo