29.1 Indentation Commands and Techniques

To move over the indentation on a line, do M-m (back-to-indentation). This command, given anywhere on a line, positions point at the first nonblank character on the line, if any, or else at the end of the line.

To insert an indented line before the current line, do C-a C-o <TAB>. To make an indented line after the current line, use C-e C-j.

If you just want to insert a tab character in the buffer, you can type C-q <TAB>.

C-M-o (split-line) moves the text from point to the end of the line vertically down, so that the current line becomes two lines. C-M-o first moves point forward over any spaces and tabs. Then it inserts after point a newline and enough indentation to reach the same column point is on. Point remains before the inserted newline; in this regard, C-M-o resembles C-o.

To join two lines cleanly, use the M-^ (delete-indentation) command. It deletes the indentation at the front of the current line, and the line boundary as well, replacing them with a single space. As a special case (useful for Lisp code) the single space is omitted if the characters to be joined are consecutive open parentheses or closing parentheses, or if the junction follows another newline. To delete just the indentation of a line, go to the beginning of the line and use M-\ (delete-horizontal-space), which deletes all spaces and tabs around the cursor.

If you have a fill prefix, M-^ deletes the fill prefix if it appears after the newline that is deleted. See Fill Prefix.

There are also commands for changing the indentation of several lines at once. They apply to all the lines that begin in the region. C-M-\ (indent-region) indents each line in the “usual” way, as if you had typed <TAB> at the beginning of the line. A numeric argument specifies the column to indent to, and each line is shifted left or right so that its first nonblank character appears in that column. C-x <TAB> (indent-rigidly) moves all of the lines in the region right by its argument (left, for negative arguments). The whole group of lines moves rigidly sideways, which is how the command gets its name.

If you want to remove all indentation from all of the line in the region, invoke C-x <TAB> with a large negative argument, such as -1000.

M-x indent-relative indents at point based on the previous line (actually, the last nonempty line). It inserts whitespace at point, moving point, until it is underneath the next indentation point in the previous line. An indentation point is the end of a sequence of whitespace or the end of the line. If point is farther right than any indentation point in the previous line, indent-relative runs tab-to-tab-stop unless it is called with a numeric argument, in which case it does nothing.

See Format Indentation, for another way of specifying the indentation for part of your text.