Emacs: icomplete vs ido mode

By Xah Lee. Date: . Last updated: .

What's the Difference Between Icomplete and Ido?

Icomplete for All Prompts, Ido for File/Buffer Commands Only

emacs icomplete mode 2017 07 10 48947
emacs Alt+x icomplete-mode

icomplete and ido are both bundled with emacs.

icomplete does completion for any command that prompts for a list of choices.:

The emacs commands that icomplete will be active Includes:

Ido only supports file/buffer related commands:

There is no config you can set to make other commands use ido completion.

emacs ido mode 2017 07 10 35659
emacs ido mode

Icomplete Needs Tab ↹ Return ↩, Ido Just Return ↩

With icomplete, you have to press Tab first to “complete”, then Enter, unless there is just one candidate left.

With ido, just press Enter, and the first candidate will be used.

Select Choices

icomplete keys for choice selection:

Arrow keys does not work.

ido keys for choice selection:

Icomplete: No Flex Matching

icomplete doesn't have flex matching. You have to type the first char of the name. However, it supports wildcard. For example, “*b” will list “abc”.

ido by default will match any substring. For example, typing “b” will list “abc”.

ido has ido-enable-flex-matching, so that it'll show candidates that contain the chars you typed. For example, “bd” will list “abcde”.

Icomplete: No Smart Order of Candidates

ido will list the most recently used item first.


I recommend turning on both icomplete and ido.

Full tutorial:

What's the Difference Between iswitchb and ido mode?

See: Emacs: iswitchb vs ido mode.

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