How do I chain multiple commands on lines matching a pattern with :g?

Explanation

The :g (global) command can execute multiple Ex commands per matching line by chaining them with |. This lets you perform complex multi-step operations on every line that matches your pattern.

How it works

" For each line matching 'pattern', run cmd1 then cmd2
:g/pattern/cmd1 | cmd2

Examples

" Delete lines matching pattern and echo a count
:let c=0 | g/DEBUG/d | let c+=1

" Comment out and indent matching lines
:g/TODO/s/^/\/\/ / | >

" Copy matching lines to end of file and uppercase them
:g/^func /t$ | $ normal gUU

" Center and add decoration to headings
:g/^# /center 80 | s/$/ =====/

Using :execute for complex operations

" Run different commands based on the match
:g/error/execute 'normal! I[ERROR] ' | s/$/;/

" Use line numbers dynamically
:g/pattern/execute 'normal! A // line ' . line('.')

Global with ranges

" Operate on matching lines plus context
:g/pattern/.,+3 s/old/new/g

" Delete matching lines and the 2 lines below them
:g/pattern/.,+2d

" Indent matching lines and their block
:g/^if/.,/^endif/ >

Tips

• Each | creates a new command in the chain, not a pipe
• :g processes lines top-to-bottom; deleting lines can shift line numbers
• Use :g/pattern/command with :v/pattern/command (inverse) for complementary operations
• :g accepts any Ex command — :s, :d, :m, :t, :normal, :execute, etc.
• This is one of the most powerful features inherited from ed — the original Unix editor
• Documented under :help :global