height of emacs bottom command line

How do I change 开发者_C百科the height of the emacs bottom command line. It seems it's a fraction of the whole frame, which takes too much space. Thanks in advance.

The minibuffer can automatically take the minimal amount of space required. There is some tweaking that you can do to help it use space more effectively. From the Emacs manual:

Normally, the minibuffer window occupies a single screen line. However, if you add two or more lines' worth of text into the minibuffer, it expands automatically to accomodate the text. The variable resize-mini-windows controls the resizing of the minibuffer. The default value is grow-only, which means the behavior we have just described. If the value is t, the minibuffer window will also shrink automatically if you remove some lines of text from the minibuffer, down to a minimum of one screen line. If the value is nil, the minibuffer window never changes size automatically, but you can use the usual window-resizing commands on it (see Windows).

According to GNU Emacs manual, section 8.3 Editing in the Minibuffer:

The variable max-mini-window-height controls the maximum height for resizing the minibuffer window. A floating-point number specifies a fraction of the frame's height; an integer specifies the maximum number of lines; nil means do not resize the minibuffer window automatically. The default value is 0.25.

In Emacs Lisp manual it is described in section 20.14 Minibuffer Miscellany.

Do you mean the minibuffer?

Using C-h v minibuffer <tab> will give you a list of minibuffer related variable and if you finish the command give you the help.

Likewise, C-h f minibuffer <tab> will give you a list of minibuffer related function.

I don't see anything obvious that would effect the height of the buffer.