A defined abbrev is a word which expands, if you insert it, into some different text. Abbrevs are defined by the user to expand in specific ways. For example, you might define foo as an abbrev expanding to find outer otter. Then you would be able to insert find outer otter into the buffer by typing f o o SPC.
A second kind of abbreviation facility is called dynamic abbrev expansion. You use dynamic abbrev expansion with an explicit command to expand the letters in the buffer before point by looking for other words in the buffer that start with those letters. See section Dynamic Abbrev Expansion.
An abbrev is a word which has been defined to expand into a specified expansion. When you insert a word-separator character following the abbrev, that expands the abbrev---replacing the abbrev with its expansion. For example, if foo is defined as an abbrev expanding to find outer otter, then you can insert find outer otter. into the buffer by typing f o o ..
Abbrevs expand only when Abbrev mode (a minor mode)
is enabled. Disabling Abbrev mode does not cause abbrev definitions to be forgotten, but they do not expand
until Abbrev mode is enabled again. The command M-x abbrev-mode
toggles Abbrev mode; with a numeric argument, it turns Abbrev mode on if the argument is positive, off otherwise.
See section Minor Modes.
Abbrev definitions can be mode-specific---active only in one major mode. Abbrevs can also have global definitions that are active in all major modes. The same abbrev can have a global definition and various mode-specific definitions for different major modes. A mode specific definition for the current major mode overrides a global definition.
Abbrevs can be defined interactively during the editing session. Lists of abbrev definitions can also be saved in files and reloaded in later sessions. Some users keep extensive lists of abbrevs that they load in every session.
The usual way to define an abbrev is to enter the text you want the abbrev
to expand to, position point after it, and type C-x
a g (
The command C-x a l (
If the text already in the buffer is the abbrev,
rather than its expansion, use command C-x a i g
To remove an abbrev definition, give a negative argument to the abbrev definition command: C-u - C-x a g or C-u - C-x a l. The former removes a global definition, while the latter removes a mode-specific definition.
An abbrev expands whenever it is present in the buffer just before point and you type a self-inserting whitespace or punctuation character (SPC, comma, etc.). More precisely, any character that is not a word constituent expands an abbrev, and any word constituent character can be part of an abbrev. The most common way to use an abbrev is to insert it and then insert a punctuation character to expand it.
Abbrev expansion preserves case; thus, foo
expands into find outer otter; Foo into Find outer otter,
and FOO into FIND OUTER OTTER or Find Outer Otter
according to the variable
These commands are used to control abbrev expansion:
You may wish to expand an abbrev with a prefix
attached; for example, if cnst expands into construction, you
might want to use it to enter reconstruction. It does not work to type recnst,
because that is not necessarily a defined abbrev. What
you can do is use the command M-' (
If you actually want the text of the abbrev in the buffer, rather than its expansion, you can accomplish this by inserting the following punctuation with C-q. Thus, foo C-q , leaves foo, in the buffer.
If you expand an abbrev by mistake, you can undo the expansion and bring back the abbrev itself by typing C-_ to undo (see section Undoing Changes). This also undoes the insertion of the non-word character that expanded the abbrev. If the result you want is the terminating non-word character plus the unexpanded abbrev, you must reinsert the terminating character, quoting it with C-q.
M-x expand-region-abbrevs searches through the region for defined abbrevs, and for each one found offers to replace it with its expansion. This command is useful if you have typed in text using abbrevs but forgot to turn on Abbrev mode first. It may also be useful together with a special set of abbrev definitions for making several global replacements at once. This command is effective even if Abbrev mode is not enabled.
The output from M-x list-abbrevs looks like this:
(Some blank lines of no semantic significance, and some other abbrev tables, have been omitted.)
A line containing a name in parentheses is the header for abbrevs in a particular abbrev table;
Within each abbrev table, each nonblank line defines one abbrev. The word at the beginning of the line is the abbrev. The number that follows is the number of times the abbrev has been expanded. Emacs keeps track of this to help you see which abbrevs you actually use, so that you can eliminate those that you don't use often. The string at the end of the line is the expansion.
M-x edit-abbrevs allows you to add, change or kill abbrev definitions by editing a list of them in an Emacs buffer. The list has the same format described above. The buffer of abbrevs is called *Abbrevs*, and is in Edit-Abbrevs mode. Type C-c C-c in this buffer to install the abbrev definitions as specified in the buffer---and delete any abbrev definitions not listed.
These commands allow you to keep abbrev definitions between editing sessions.
M-x write-abbrev-file reads a file name using the minibuffer and then writes a description of all current abbrev definitions into that file. This is used to save abbrev definitions for use in a later session. The text stored in the file is a series of Lisp expressions that, when executed, define the same abbrevs that you currently have.
M-x read-abbrev-file reads a file name
using the minibuffer and then reads the file, defining
abbrevs according to the contents of the file. M-x quietly-read-abbrev-file is the same except that it does not
display a message in the echo area saying that it is
doing its work; it is actually useful primarily in the .emacs file. If an empty
argument is given to either of these functions, they use the file name specified in the variable
Emacs will offer to save abbrevs automatically if you have changed any of them,
whenever it offers to save all files (for C-x s or C-x C-c). This
feature can be inhibited by setting the variable
The commands M-x insert-abbrevs and M-x define-abbrevs are similar to the previous commands but work on text in an Emacs buffer. M-x insert-abbrevs inserts text into the current buffer before point, describing all current abbrev definitions; M-x define-abbrevs parses the entire current buffer and defines abbrevs accordingly.
The abbrev facility described above operates automatically as you insert text, but all abbrevs must be defined explicitly. By contrast, dynamic abbrevs allow the meanings of abbrevs to be determined automatically from the contents of the buffer, but dynamic abbrev expansion happens only when you request it explicitly.
For example, if the buffer contains does this follow and you type f o M-/, the effect is to insert follow because that is the last word in the buffer that starts with fo. A numeric argument to M-/ says to take the second, third, etc. distinct expansion found looking backward from point. Repeating M-/ searches for an alternative expansion by looking farther back. After considering the entire buffer before point, it searches the text after point. After searching all of the current buffer, M-/ searches other buffers.
A negative argument to M-/, as in C-u - M-/, says to search first for expansions after point, and second for expansions before point. If you repeat the M-/ to look for another expansion, do not specify an argument. This tries all the expansions after point and then the expansions before point.
After you have expanded a dynamic abbrev, you can copy additional words that follow the expansion in its original context. Simply type SPC M-/ for each word you want to copy. The spacing and punctuation between words is copied along with the words.
In shell scripts and makefiles, a variable name is
sometimes prefixed with $ and sometimes not. Major modes for this kind of text can customize dynamic abbreviation to handle
optional prefixes by setting the variable
The command C-M-/ (
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