Add Display Line Numbers While Using Less as a Unix TIL

unix/display-line-numbers-while-using-less.md

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+# Display Line Numbers While Using Less
+
+Including line numbers while viewing files with `less` can provide useful
+context for understanding where you are within the file. This is especially true
+if you've used `&` to filter down to lines that match a pattern.
+
+You can start `less` with line numbers with the `-N` flag (or `--LINE-NUMBERS`
+if you really want to spell it out).
+
+```bash
+$ less -N log/development.log
+```
+
+If you've already started up `less` and wish you had included line numbers,
+there is no reason to restart it with the flag. Instead, toggle the line numbers
+option on within the `less` process. To do this, type `-N`. It will prompt you
+with `Constantly display line numbers (press RETURN)`. Hit enter and line
+numbers will appear to the left of each line in the file.
+
+Similarly, to toggle line numbers back off within `less`, hit `-n` (lower-case
+`n`), accept the prompt, and back off they go.
+
+Both of these (`-N`/`-n`) are options being set (toggled) via the `-` command.
+There are many other options like these that can be configured within a `less`
+session in the same way.
+
+See `man less` and find the `-` command and the available `OPTIONS`.