nvim

TLDR

Open a file

$ nvim [path/to/file]

Enter text editing mode (insert mode)

$ <Esc>i

Copy ("yank") or cut ("delete") the current line (paste it with P)

$ <Esc>[yy|dd]

Enter normal mode and undo the last operation

$ <Esc>u

Search for a pattern in the file (press n/N to go to next/previous match)

$ <Esc>/[search_pattern]<Enter>

Perform a regular expression substitution in the whole file

$ <Esc>:%s/[regular_expression]/[replacement]/g<Enter>

Enter normal mode and save (write) the file, and quit

$ <Esc>:wq<Enter>

Quit without saving

$ <Esc>:q!<Enter>