How can I repeat last substitution and with the same flags

Question

& repeats the last :s

But it doesn't repeat with flags, e.g. a global sub:

:s/"/'/g

won't replace in the same way on consecutive lines with &, running :s/"/'/g on the first line here and then & on the second

["first", "second"]
["third", "fourth"]

produces

['first', 'second']
['third", "fourth"]

the global option has been forgotten about when using & on the second line

How can I quickly repeat last substitute command with flags?

(not @: because I may have other commands run after :s)

Answer 1

This is exactly what :&& does:

                            *:&&*
[&] Must be the first one: Keep the flags from the previous substitute
    command.  Examples: >
        :&&
        :s/this/that/&
<   Note that `:s` and `:&` don't keep the flags.

There are also the & and g& commands:

                                *&*
&           Synonym for `:s` (repeat last substitute).  Note
            that the flags are not remembered, thus it might
            actually work differently.  You can use `:&&` to keep
            the flags.

                                *g&*
g&          Synonym for `:%s//~/&` (repeat last substitute with
            last search pattern on all lines with the same flags).
            For example, when you first do a substitution with
            `:s/pattern/repl/flags` and then `/search` for
            something else, `g&` will do `:%s/search/repl/flags`.
            Mnemonic: global substitute.

And you could map & to be more like :&&:

nnoremap & :&&<CR>
xnoremap & :&&<CR>

Answer 2

I usually use a range operation for substitutions. From the example:

["first", "second"]
["third", "fourth"]

Replacing " with ', while cursor is on first line:

:.,+1s/"/'/g

Or from start of file to end of file:

:1,$s/"/'/g

. = current line of file, $ = last line of file, +x = delta line (positive offset), -x = delta line (negative offset), g = globally (all occurrences on line)