Problem with sed to insert a new line

[Andrew Pantyukhin]

On 6/28/07, Olivier Regnier <oregnier at oregnier.net> wrote:
> Hi everyone,
>
> I have a file called "test" with the following lines:
> ###
> a
> b
>
> d
> e
> f
> ###
>
> With sed, i want to insert the "c" letter after "b" letter. Logically
> simple, but not for me.
>
> Here is my command : # sed -i.old -e "4i\c"
>
> I have this message : sed: 1: "4i\c": extra characters after \ at the
> end of i command

AFAIK, with our sed you can only do that with multiline
command:
% sed -i.old -e "4i\\<press enter>
c" test

The backslash is doubled, because shells interpret
backslash-newline as a space. With GNU sed it's
much easier.