Re: mapfile -C issue

[Greg Wooledge]

On Sun, Jun 18, 2023 at 02:52:48AM +0200, alex xmb ratchev wrote:
> i expected
> 1 11
> 2 22
> 3 33
> 1 44
> 2 55
> 3 66
> 
> or the same with 0 as beginning instead of 1

Then you want the callback function to be called every time, instead
of every 3rd time.

unicorn:~$ C() { printf '%d %d\n' "$(($1%3))" "$2"; }
unicorn:~$ mapfile -t -C C -c 1 foo < <(printf %s\\n 11 22 33 44 55 66)
0 11
1 22
2 33
0 44
1 55
2 66

You could use $(($1%3 + 1)) to get 1 2 3 1 2 3.  In any case, it's the %3
in the callback function, and the use of -c 1, that are important here.