Executing a command on delimited lines

Question

How can I run a command on all lines delimited, say by \begin{otherlanguage} and \end{otherlanguage}?

For example,

1 This line should not be affected,
2 \begin{otherlanguage}
3 but this should;
4 \end{otherlanguage}
5 this should not.

(The cmd could be norm A test.)

Answer 1

You can use pattern delimiter for this:

:/first/,/second/norm dd

You can use any search pattern around the ,.

If you want to use only the inside of the matched patterns, use + and - like so:

:/first/+1,/second/-1 norm dd

Answer 2

A more specific answer (since you seem to be editing a TeX file): if you use the vimtex plugin (although LaTeX-Box also has this IIRC), you can easily select the whole environment (without the \begin and \end marker lines) using the inside environment text object (ie). So, assuming the cursor is somewhere inside the otherlanguage environment, your example can be "solved" with something like:

vie:norm A test

For more vimtex mappings, see :h vimtex-default-mappings.