vi 에서 탭 문자 찾기

>Is there a handy command to display all the TAB characters in a file?
>And for a large file, is there a way I can search it in VIM?

One easy way is ":set list".  It also shows other control characters, but
it may be exactly what you need.  Turn it off with ":set nolist".
If that doesn't do it, you can do / C-V C-I (slash control-V control-I) to
search for a tab character.  If you have highlighting turned on, that will
highlight the blank spaces that contain a tab.