TopolearnIt turns 'delete every line containing X' or 'apply this macro to every matching line' into one command.
:[range]g/pattern/command marks every line matching the pattern, then runs the Ex command on each. The default range is the whole file and the default command is p (print).
:g/DEBUG/ddeletes every line containing DEBUG.:g!/pattern/dor:v/pattern/ddeletes every line not matching, i.e. keeps only matches.:g/^\s*$/dremoves blank lines.:g/TODO/t$copies all TODO lines to the end of the file (t= copy,m= move).:g/^/m0reverses the file: each line is moved to the top in turn.
Combined with :normal, any Normal-mode keystrokes can be applied to the matching lines: :g/^def /normal A: appends a colon, and :g/pattern/normal @q runs a macro only where it is needed.
You can also nest a substitute to restrict it: :g/^SELECT/s/foo/bar/g replaces only on lines starting with SELECT. With an empty substitute pattern the inner :s reuses the global pattern: :g/old/s//new/g.
The whole :g operation is a single undoable change, so one u restores everything. Use :g/pattern/ (print) first to preview which lines are affected, or :g/pattern/# to show them with line numbers.
Example
:g/console\.log/d " delete all console.log lines
:v/error/d " keep only lines containing 'error'
:g/^\s*$/d " delete blank lines
:g/TODO/# " list TODO lines with numbers
:g/^def /normal A # noqa " append a comment to def lines
:g/^import/m0 " move imports to the top (reversed order)
:g/^SELECT/s/;$// " strip ';' only on SELECT lines
:g/^/m0 " reverse the whole fileRemember
- :g/pat/cmd on matches, :v/pat/cmd on non-matches
- Combine with d, m, t, s and normal
- A whole :g run undoes with a single u
Watch out for
- Running a destructive :g without previewing; :g/pat/ alone prints the lines first.