Remove everything except regex match in Vim -

my specific case text document contains lots of text , ipv4 addresses. want remove except ip addresses.

i can use :vglobal search ([0-9]{1,3}\.){3}[0-9]{1,3} , remove lines without ip addresses, after know how search whole line , select matching text. there easier way.

in short, i'm looking way following without using external program (like grep):

grep --extended-regexp --only-matching --regexp="([0-9]{1,3}\.){3}[0-9]{1,3}" 

calling grep vim may require adapting regex (ex: removing \v). using vim's incremental search shows me i've got pattern right, , don't want verify regex in grep too.

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edit: peter, here's function use. (c register clobber in functions.)

"" remove text except matches current search result "" opposite of :%s///g (which clears instances of current search). function! clearallbutmatches()     let old = @c     let @c=""     %s//\=setreg('c', submatch(0), 'l')/g     %d _     put c     0d _     let @c = old endfunction 

edit2: made command accepts ranges (but defaults whole file).

"" remove text except matches current search result. put each "" match on own line. opposite of :%s///g (which clears "" instances of current search). function! s:clearallbutmatches() range     let is_whole_file = a:firstline == 1 && a:lastline == line('$')      let old_c = @c      let @c=""     exec a:firstline .','. a:lastline .'sub//\=setreg("c", submatch(0), "l")/g'     exec a:firstline .','. a:lastline .'delete _'     put! c      "" want above replace whole selection c, i'll     "" settle removing blank line that's left when deleting file     "" contents.     if is_whole_file         $delete _     endif      let @c = old_c endfunction command! -range=% clearallbutmatches <line1>,<line2>call s:clearallbutmatches() 

this effect can accomplished using sub-replace-special substitution , setreg() linewise

:let @a="" :%s//\=setreg('a', submatch(0), 'l')/g :%d _ :pu :0d _ 

or in 1 line such:

:let @a=""|%s//\=setreg('a', submatch(0), 'l')/g|%d _|pu a|0d _ 

overview: using substitution append each match register "a" linewise replace entire buffer contents of register "a"

explanation:

1. let @a="" empty "a" register appending into
2. %s//\=setreg('a', submatch(0), 'l')/g substitute globally using last pattern
3. the \=expr replace pattern contents of expression
4. submatch(0) entire string of matched
5. setreg('a', submatch(0), 'l') append (note: capital "a") @a matched string, linewise
6. %d _ delete every line black hole register (aka @_)
7. pu a put contents of @a buffer
8. 0d _ delete first line

concerns:

• this trash 1 of registers. example trashed @a
• uses last search pattern. although can modify substitute command whatever pattern want: %s/<pattern>/\=setreg('a', submatch(0), 'l')/g

for more help

:h :s\= :h :let-@ :h submatch() :h setreg() :h :d :h :p