How to find files that contain two or more of a specific character?

I’m learning about wildcards and I’m trying to figure out how to find filenames that contain a specific character, two or more times.

For example, finding filenames that have two or more x‘s in them, such as Xerox.

I know how to find files that have an *x, or that have an *ox*, but I can’t figure out how I’d find a file named Xerox.

Any help is much appreciated.

Answer

For finding files that contain two or more x‘s, you want to use a regular expression.

ls | egrep x.*x is an example.

Take a look at this Regular Expression cheatsheet. This will work because you match a single x, followed by 0 or more of any character (represented by .*), followed by another x.