29 Indentation
This chapter describes the Emacs commands that add, remove, or
adjust indentation.
- <TAB>
- Indent the current line “appropriately” in a mode-dependent fashion.
- C-j
- Perform <RET> followed by <TAB> (
newline-and-indent).
- M-^
- Merge the previous and the current line (
delete-indentation).
This would cancel the effect of a preceding C-j.
- C-M-o
- Split the current line at point; text on the line after point becomes a
new line indented to the same column where point is located
(
split-line).
- M-m
- Move (forward or back) to the first nonblank character on the current
line (
back-to-indentation).
- C-M-\
- Indent lines in the region to the same column (
indent-region).
- C-x <TAB>
- Shift lines in the region rigidly right or left (
indent-rigidly).
- M-i
- Indent from point to the next prespecified tab stop column
(
tab-to-tab-stop).
- M-x indent-relative
- Indent from point to under an indentation point in the previous line.
Emacs supports four general categories of operations that could all
be called `indentation':
- Insert a tab character. You can type C-q <TAB> to do this.
A tab character is displayed as a stretch of whitespace which extends
to the next display tab stop position, and the default width of a tab
stop is eight. See Display Custom, for more details.
- Insert whitespace up to the next tab stop. You can set tab stops at
your choice of column positions, then type M-i to advance to the
next tab stop. The default tab stop settings have a tab stop every
eight columns, which means by default M-i inserts a tab
character. To set the tab stops, use M-x edit-tab-stops.
- Align a line with the previous line. More precisely, the command
M-x indent-relative indents the current line under the beginning
of some word in the previous line. In Fundamental mode and in Text
mode, <TAB> runs the command
indent-relative.
- The most sophisticated method is syntax-driven indentation.
Most programming languages have an indentation convention. For Lisp
code, lines are indented according to their nesting in parentheses. C
code uses the same general idea, but many details are different.
Type <TAB> to do syntax-driven indentation, in a mode that
supports it. It realigns the current line according with the syntax
of the preceding lines. No matter where in the line you are when you
type <TAB>, it aligns the line as a whole.
Normally, most of the above methods insert an optimal mix of tabs and
spaces to align to the desired column. See Just Spaces, for how to
disable use of tabs. However, C-q <TAB> always inserts a
tab, even when tabs are disabled for the indentation commands.