Vim misses a few files when opening multiple files

Question

I use vim -o a* to open 25 files (filenames starting with 'a') together and search & replace (:windo %s/old/new/gcI) some common word in these files. Later I found that not all of them have been modified and it seems to be due to that vim -o opens only 23 of them. However, vim -O a* can open all 25 files.

So is there any safe way to make sure every file is opened (and thus modified), hopefully not by counting windows by eyes.

Answer 1

In a slightly different take, vim also preserves the files given it on the command-line in an argument list (colloquially: :args). When you use :next/:prev, you traverse that list. You can change, add to, and operate further on that list with many functions/commands (see the help).

Of particular note is :argdo which, alongside its cousins :bufdo, :windo, :tabdo, :cdo, and :ldo, traverses the list and runs a command.

So in your case, I would do

$ vim a*
:argdo %substitute/old/new/g

Alternately:

$ vim a*
:vimgrep /old/ ##
:cdo substitute//new/g

Where this version first searches for the word to change in the arglist (##) and then applies the change. The advantage here is the quickfix list gives you a preview of all the occurrences about to be changed. If you don’t like it, you can try a different search pattern or use the :Cfilter command from a built-in package.

Answer 2

When opening multiple files, Vim will only create as many windows as it can display, and load the rest without displaying them, in what we call buffers.

The help states:

Summary:
   A buffer is the in-memory text of a file.
   A window is a viewport on a buffer.
   A tab page is a collection of windows.

You can display a list of currently open buffers with :ls. You could also use Fzf and the :Buffers command it provides.

You can access any buffer with :buffer [name or number], and navigate with :bnext and :bNext, or :bn and :bp (next / previous).

You may want to take a look at :h windows, especially the sections covering "buffers".