Add Line Numbers

In short Adding line numbers puts a number at the start of every line, with a configurable start value, step, zero-padding and separator. Padding is the option people skip and then need: without it, line 9 and line 10 have different widths and nothing aligns, so a numbered list of a hundred lines looks ragged. Padding to a fixed width fixes it in one setting. The start value matters when you are numbering part of something — a code excerpt that begins at line 240 of a file should be numbered from 240, not from 1, or every reference you make to it is wrong. The step exists for the same reason: numbering by tens or by twos matches the conventions used in scripts, legal documents and verse. Two things to decide before you run it. Whether blank lines get numbers changes the count and is genuinely a preference. And the numbers become part of the text, so anything you do afterwards — sorting, searching, pasting into code — sees them. Number last, not first.