I want to do so because I want to copy content from one file to another in vi.
From here.
You can open two files in one bash window using VIM’s “:split” command:
Open a file with “$ vim file1”, open a second file within VIM using “:split file2” command.
Or, use $ vim -o file1 file2 from bash.
Switch between files(toggle active file) in VIM with “ctrl-w”.
An example operation is copy (or yank) in file1 “y”, switch(“ctrl-w”), then paste (or put) “p” content into file2.
Everything else is normal when either window is active, thus “:q” quits and “:q!” force quits.