Vim

ci"      change the text inside the quotes the cursor is in
da(      delete the parenthesised group including the parentheses
yip      yank the paragraph
>ap      indent the paragraph and its trailing blank line
gUiw     uppercase the word
d2w      delete two words; 2dw does the same
c3j      change this and the three lines below
dt,      delete up to but not including the next comma
=i{      re-indent the block inside braces

"ayy      yank the line into a
"Ayy      append the next line to a
"ap       paste a
"0p       paste the last yank even after several deletes
"+y       yank a visual selection to the system clipboard
:reg a0"  show these registers
:let @a=''  clear a

qa        start recording into a
0f=lct;"$HOME/bin"<Esc>j    the edit, ending with a move to the next line
q         stop
@a        replay once
5@a       replay five times
@@        repeat the last macro
:'<,'>normal @a    run on each line of a visual selection
:g/TODO/normal @a  run on each line matching TODO

/\<word\>       whole word
/\vfoo(bar)@!   foo not followed by bar (lookahead)
/\d\{3}         three digits
/^\s*$          blank lines
/foo\_.*bar     across lines: \_ prefixes a class to include newline

:%s/old/new/g        every occurrence on every line; without g only the first per line
:%s/old/new/gc       confirm each: y, n, a (all), q, l (this one then quit)
:s/\(\w\+\) \(\w\+\)/\2 \1/     swap two words with groups
:%s/\v(\w+)@(\w+)/\2 at \1/     the same with very magic
:%s/foo/\U&/g        & is the match; \U uppercases to the end or \E
:%s/\s\+$//e         strip trailing whitespace; e suppresses "pattern not found"
:%s#/usr/local#/opt#g    any delimiter works when the pattern contains slashes
:%s/x/\r/g           \r inserts a newline in the replacement; \n would insert a NUL
:%s/\n\n\+/\r\r/     collapse runs of blank lines to one
:%s//new/g           empty pattern reuses the last search
:%s/\<\(\w\)\(\w*\)\>/\u\1\L\2/g   Title Case each word
:%s/pat/\=line('.')/   \= evaluates an expression as the replacement
&  or :&&            repeat the last substitute on this line, with the same flags
g&                   repeat it on every line

:g/^\s*#/d           delete comment lines
:v/error/d           keep only lines containing error
:g/^$/,/./-j         join each run of blank lines into one
:g/func/normal A;    append ; to every line containing func
:g/pat/m0            reverse the order of matching lines (move each to the top)
:g/pat/t$            copy matching lines to the end
:g/^Host /+1s/^/    /    indent the line after each Host line
:g/pat/s/a/b/        substitute only on matching lines

:e path           edit a file (open a buffer); :e! discards changes and reloads
:ls               list buffers; % is current, # alternate, + modified, h hidden
:b 3  :b name     switch by number or partial name (Tab completes)
:bn :bp  C-^      next, previous, toggle with the alternate buffer
:bd               delete (unload) the buffer; :bd! discards changes
:bufdo %s/a/b/ge | update    run a command in every buffer and save the changed ones
:sp path  :vs path    split horizontally, vertically
C-w s  C-w v      split the current buffer
C-w h j k l       move between windows; C-w w cycles
C-w H J K L       move the window to the far left, bottom, top, right
C-w o             close every other window
C-w =             equalise sizes; C-w _ maximise height; C-w | width; 10 C-w + grow by ten
C-w q  :q         close the window; the buffer stays loaded
:tabnew path      new tab; gt gT move between; :tabclose
:windo diffthis   run a command in every window of the tab
:find name        search the path option; set path+=** for recursive lookup in the project
:args **/*.go     set the argument list; :argdo runs a command over it

set nocompatible                 " Vim, not vi; implied when a vimrc exists but harmless
filetype plugin indent on
syntax enable
set encoding=utf-8
set hidden                       " switch buffers without saving
set backspace=indent,eol,start   " backspace over everything in Insert
set incsearch hlsearch ignorecase smartcase
set scrolloff=5 sidescrolloff=5
set number relativenumber        " absolute on the cursor line, relative elsewhere: counts for j/k
set wildmenu wildmode=longest:full,full
set laststatus=2 ruler showcmd
set ttimeout ttimeoutlen=50      " Escape is recognised quickly, key codes still work
set nrformats-=octal             " C-a on 007 gives 008, not 010
set autoread                     " reload a file changed outside Vim when it is unmodified
set undofile undodir=~/.vim/undo//   " persistent undo; create the directory
set noswapfile                   " or set directory=~/.vim/swap// to keep them out of the tree
set splitbelow splitright
set list listchars=tab:▸\ ,trail:·,nbsp:␣
set expandtab shiftwidth=4 softtabstop=4   " ftplugins override per filetype
set formatoptions+=j             " remove comment leaders when joining lines
set mouse=a
set clipboard=unnamedplus        " y and p use the system clipboard when available
let mapleader = ' '
nnoremap <leader>w :update<CR>
nnoremap <silent> <leader>h :nohlsearch<CR>
nnoremap Q gq

-- ~/.config/nvim/init.lua: the same settings as the vimrc above
vim.o.number = true
vim.o.relativenumber = true
vim.o.undofile = true
vim.o.expandtab = true
vim.o.shiftwidth = 4
vim.o.softtabstop = 4
vim.o.splitbelow = true
vim.o.splitright = true
vim.o.list = true
vim.o.listchars = 'tab:▸ ,trail:·,nbsp:␣'
vim.o.clipboard = 'unnamedplus'
vim.g.mapleader = ' '
vim.keymap.set('n', '<leader>w', '<Cmd>update<CR>')
vim.keymap.set('n', '<leader>h', '<Cmd>nohlsearch<CR>', { silent = true })
vim.cmd.colorscheme('habamax')

]c  [c            next, previous change
do                obtain: pull the other window's hunk into this one (:diffget)
dp                put: push this hunk to the other window (:diffput)
:diffget //2      in a three-way merge, take from the left (LOCAL) buffer; //3 is REMOTE
:diffupdate       recompute after manual edits
zo zc zR zM       open, close a fold; open, close all
:set diffopt+=iwhite          ignore whitespace changes
:set diffopt+=algorithm:patience,indent-heuristic   diff algorithm; 8.1+ and Neovim
:windo diffthis   compare two already-open windows; :diffoff! ends it
:wqa              save every buffer and quit

" Delete trailing whitespace in the whole file
:%s/\s\+$//e

" Convert tabs to spaces per the current settings, or the reverse with noexpandtab
:set expandtab | retab

" Sort the visual selection, removing duplicates
:'<,'>sort u

" Sort by the number in each line
:%sort n

" Reverse every line in the file
:g/^/m0

" Number each line in the selection
:'<,'>s/^/\=line('.') - line("'<") + 1 . '. '/

" Insert the output of a command below the cursor
:r !date -Is

" Replace the buffer with the output of a filter
:%!jq .

" Format a JSON selection in place
:'<,'>!python3 -m json.tool

" Run the current line as a shell command and replace it with the output
!!sh

" Write the selection to a file
:'<,'>w part.txt

" Open every file containing a pattern, one per buffer, and jump through matches
:grep -r pattern . | copen      then :cn :cp

" Substitute across the quickfix list (Vim 8+, Neovim): grep, then
:cdo s/old/new/g | update

" Increment a column of numbers, one more each line: select with C-v, then
g C-a

" Join all lines into one
:%j

" Split a line on commas
:s/,/\r/g

" Change the file's line endings to Unix
:set ff=unix | w

" Show the character under the cursor as a code point
ga

" Show the full path of the current file
:echo expand('%:p')      or C-g, or 1 C-g

" Change to the directory of the current file
:cd %:h

" Open the file name under the cursor, or the URL with a handler
gf    gx

" Diff the buffer against the file on disk
:w !diff % -

" Spell check with the Australian dictionary
:setlocal spell spelllang=en_au     then ]s z= zg

" Open the file with the cursor at a line, at a pattern
vim +42 file      vim +/pattern file

" Run Ex commands from the shell without opening the editor
vim -es -c '%s/foo/bar/g' -c 'wq' file

" Encrypt a file (Vim only; Neovim removed it)
vim -x secrets.txt

#!/usr/bin/env bash
# usage: vim-batch '<ex command>' file...
# Example: vim-batch '%s/\v<colour>/color/g' src/*.md
set -euo pipefail
cmd=${1:?ex command}; shift
for f in "$@"; do
  [[ -f $f ]] || { printf 'skip: %s\n' "$f" >&2; continue; }
  vim -es -u NONE -i NONE -c "set nomore" -c "$cmd" -c 'update' -c 'qa!' -- "$f" </dev/null \
    || printf 'failed: %s\n' "$f" >&2
done

#!/usr/bin/env bash
set -euo pipefail
dir=${1:-$HOME}
find "$dir" -type f \( -name '.*.swp' -o -name '.*.swo' \) -print0 | while IFS= read -r -d '' swp; do
  pid=$(vim -r "$swp" 2>&1 | awk '/process ID/ {print $NF}' | tr -dc '0-9' || true)
  if [[ -n $pid ]] && kill -0 "$pid" 2>/dev/null; then
    printf 'in use by %s: %s\n' "$pid" "$swp"
  else
    printf 'stale: %s\n' "$swp"
    [[ ${DELETE:-0} == 1 ]] && rm -f -- "$swp"     # DELETE=1 removes; default is report only
  fi
done

#!/usr/bin/env bash
set -euo pipefail
log=$(mktemp)
trap 'rm -f "$log"' EXIT
vim --startuptime "$log" -c 'qa!' "${1:-}" >/dev/null 2>&1 </dev/null
printf 'total: %s ms\n' "$(tail -1 "$log" | awk '{print $1}')"
grep -E 'sourcing|require' "$log" | sort -k2 -rn | head -15    # column 2 is the elapsed time of that item