How do I repeat the last substitute command preserving its flags?

Explanation

After running a :s/pattern/replacement/g command, you often need to repeat it on another line or range. The :& command repeats the last substitution, but it drops the original flags. Using :&& repeats it with the original flags intact, which is almost always what you want.

How it works

• :& — repeat the last :s command on the current line, but without any flags (no g, c, i, etc.)
• :&& — repeat the last :s command on the current line with the original flags preserved
• :%&& — repeat the last :s with original flags across the entire file
• :'<,'>& — repeat on a visual selection (add & for flags)

Example

Suppose you run this substitution:

:s/foo/bar/gi

Then move to another line:

:&   " runs :s/foo/bar/  (flags dropped — only replaces first match, case-sensitive)
:&&  " runs :s/foo/bar/gi (flags preserved — replaces all, case-insensitive)

Tips

• In normal mode, & is equivalent to :s (repeats without flags) — use :&& explicitly when flags matter
• Combine with a range to apply across multiple lines: :5,20&&
• The g& normal-mode shortcut runs :%s//~/& which repeats the last substitute across the whole file with flags