[[using-shell-customization-commandnotfound]]
=== Command Not Found
ifndef::snippets[:snippets: ../../test/java/org/springframework/shell/docs]

On default a missing command is handled via `CommandNotFoundResultHandler`
and outputs a simple message:

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[source, text]
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shell:>missing
No command found for 'missing'
----
====

Internally `CommandNotFoundResultHandler` is using `CommandNotFoundMessageProvider`
which is a simple function taking a `ProviderContext` and returning a text
message. Below is an example what a custom message provider might look like.

====
[source, java, indent=0]
----
include::{snippets}/CommandNotFoundSnippets.java[tag=custom-provider]
----
====

It's possible to change this implementation by defining it as a bean.

====
[source, java, indent=0]
----
include::{snippets}/CommandNotFoundSnippets.java[tag=provider-bean-1]
----
====

`CommandNotFoundResultHandler` is a functional interface so it can
be writter as a lambda.

====
[source, java, indent=0]
----
include::{snippets}/CommandNotFoundSnippets.java[tag=provider-bean-2]
----
====