I know that the GitHub web interface lets you search all repositories for files with a particular pathname (e.g. searching for path:/app/models/user.rb
yields >
Does the search user.rb in:path
do what you want to do?
Alternatively there is also this search filename:user.rb
Found on: https://help.github.com/articles/searching-code/
In my case, I wanted to search for a particular file name, in all of my organization's repositories. This can be done by entering this in the search box:
org:your-organization-user-name filename:the-file-name
Of course, just do "filename:the-file-name" if you want to search the whole of GitHub.
I didn't see this in https://help.github.com/articles/searching-code/ but found out when I switched context, and GitHub entered the filter for me automaticallly.