You can view the change history of a file by clicking on the history button, or by adding commits
to the URL of the file. Here is what it looks like for a file at the Homebrew repository on GitHub:
https://github.com/mxcl/homebrew/commits/master/SUPPORTERS.md
To get a line-by-line history, simply add the SHA-1 string of the commit for which you want to see the diff to the URL after the word commit
, and then anchor it with the filename you are interested in. For the same file above:
https://github.com/mxcl/homebrew/commit/288f001e924d5365b79c279e4478f372a04011ae#SUPPORTERS.md
To see all commits for a single branch use a URL like this
https://github.com/mxcl/homebrew/commits/master
To see all commits for all branches use a URL like this
https://github.com/mxcl/homebrew/commits
There is no button or link in the web UI for these URLs, but you can bookmark them easily.