19.13 Optional Mode Line Features

The buffer percentage pos indicates the percentage of the buffer above the top of the window. You can additionally display the size of the buffer by typing M-x size-indication-mode to turn on Size Indication mode. The size will be displayed immediately following the buffer percentage like this:

POS of SIZE

Here SIZE is the human readable representation of the number of characters in the buffer, which means that ‘k’ for 10^3, ‘M’ for 10^6, ‘G’ for 10^9, etc., are used to abbreviate.

If you have narrowed the buffer (see section Narrowing), the size of the accessible part of the buffer is shown.

The current line number of point appears in the mode line when Line Number mode is enabled. Use the command M-x line-number-mode to turn this mode on and off; normally it is on. The line number appears after the buffer percentage pos, with the letter ‘L’ to indicate what it is. See section Minor Modes, for more information about minor modes and about how to use this command.

If you have narrowed the buffer (see section Narrowing), the displayed line number is relative to the accessible portion of the buffer. Thus, it isn't suitable as an argument to goto-line. (Use what-line command to see the line number relative to the whole file.)

If the buffer is very large (larger than the value of line-number-display-limit), then the line number doesn't appear. Emacs doesn't compute the line number when the buffer is large, because that would be too slow. Set it to nil to remove the limit.

Line-number computation can also be slow if the lines in the buffer are too long. For this reason, Emacs normally doesn't display line numbers if the average width, in characters, of lines near point is larger than the value of the variable line-number-display-limit-width. The default value is 200 characters.

You can also display the current column number by turning on Column Number mode. It displays the current column number preceded by the letter ‘C’. Type M-x column-number-mode to toggle this mode.

Emacs can optionally display the time and system load in all mode lines. To enable this feature, type M-x display-time or customize the option display-time-mode. The information added to the mode line usually appears after the buffer name, before the mode names and their parentheses. It looks like this:

hh:mmpm l.ll

Here hh and mm are the hour and minute, followed always by ‘am’ or ‘pm’. l.ll is the average number of running processes in the whole system recently. (Some fields may be missing if your operating system cannot support them.) If you prefer time display in 24-hour format, set the variable display-time-24hr-format to t.

The word ‘Mail’ appears after the load level if there is mail for you that you have not read yet. On a graphical display you can use an icon instead of ‘Mail’ by customizing display-time-use-mail-icon; this may save some space on the mode line. You can customize display-time-mail-face to make the mail indicator prominent. Use display-time-mail-file to specify the mail file to check, or set display-time-mail-directory to specify the directory to check for incoming mail (any nonempty regular file in the directory is considered as “newly arrived mail”).

By default, the mode line is drawn on graphics displays with 3D-style highlighting, like that of a button when it is not being pressed. If you don't like this effect, you can disable the 3D highlighting of the mode line, by customizing the attributes of the mode-line face. See section Customizing Faces.

By default, the mode line of nonselected windows is displayed in a different face, called mode-line-inactive. Only the selected window is displayed in the mode-line face. This helps show which window is selected. When the minibuffer is selected, since it has no mode line, the window from which you activated the minibuffer has its mode line displayed using mode-line; as a result, ordinary entry to the minibuffer does not change any mode lines.

You can disable use of mode-line-inactive by setting variable mode-line-in-non-selected-windows to nil; then all mode lines are displayed in the mode-line face.

You can customize the mode line display for each of the end-of-line formats by setting each of the variables eol-mnemonic-unix, eol-mnemonic-dos, eol-mnemonic-mac, and eol-mnemonic-undecided to the strings you prefer.